 Welcome, everyone, to this new seminar of the Integrative Research Seminar Series, whose purpose is to make now the research of professors of the Department of Information and Communication Technologies within the University. And my pleasure today is to introduce Tony Borla. Okay, he heads one of the groups here in biomedical electronics research. He got his PhD 10 years ago at the Polytechnical University, and since then he has been traveling quite a lot. He is currently a Sarah Hunter professor, but before that he was a Marie Curie Fellow, a Ramanica Health Fellow and so on. Here, the last five years I think at the University of Pompeo Fabram, he was in France, he was also in Berkeley, California, and traveled a lot. Okay, today the title, it's there. So I was telling Tony that when I was reading the title, Healing Signals, Delivery of Electrical Currents, it was like a contrast between the two things, but he'll explain how to do things go together. So without further ado, so Tony, thank you. Thanks, Héctor, for the introductions and thank you all for being here. To listen about the research we are performing at the Biomedical Electronics Research Group, which basically it's about applying currents to living organisms, to tissues for biomedical applications. More specifically, we are interested in medical applications. We are interested in the phenomena related to the delivery of those currents, and that happens with those currents when they go into living tissues, let's say, but more than in the phenomenon, we are interested in the applications. So that's basically what I'm going to talk about that. And before talking about the project, we are working on the project that we have been working recently. I need to introduce a little bit what are the effects of applying currents to living tissues. For that, what I'm going to use is a model for the cell, a very simple model for the cell in which we consider that the cell, the living cell, the biological cell is just an electrolyte solution, so an ionic solution, surrounded or sealed by a thin, fat layer, the plasma membrane, the cell membrane, and which separates it from the external medium, which is just an electrolyte solution, also an ionic solution. In turn, I'm also doing an approximation, which is what engineers do, of the tissues just as a regular, very symmetrical aggregation of cells. Of course, those are very rough approximations, actual tissues are much more complex than that. These are actual slides, histological slides from soft tissues, different tissues, and the cell itself, the biological cell, it's much more complex than that. But this model is quite good for describing what happens in terms of electrical properties of a tissue or of a cell. So we have this model, we start with that, and the first thing that we will observe is that if we apply very low currents, very low magnitude currents, we are basically not going to do anything to the biological cell. But by delivering this current, we are going to be able to measure the voltage that drops. So we are going to be able to measure the impedance of a tissue or of a cell in suspension. And if we take these impedance measurements and try to match what we see to an electric circuit, what we are going to see is that the properties of what, so the data that we record matches quite well this circuit. And this circuit makes sense according to this model. Basically, what we have is a resistor that models what happens in terms of the extracellular space. So the extracellular space has said that it's an ionic solution, we approximated it as an ionic solution. So basically we have a conductive material there. So it's going to behave as an element, as a resistance that obeys the Ohm's law. The same thing happens with the interior of the cell. The interior of the cell is also going to be an ionic solution. So basically it's going to behave as another resistance. And in between these two conductive media, we have a fat layer. We are talking about something burry thing. We are talking about something in the order of 5 nanometers. So if you remember your basic courses on physics, we have two conductive media, two metallic plates, and we have an insulator in between those two conductive media. What we have is a capacitor, a capacitance. So this is what we are going to observe if we apply very low currents. And this is what we typically refer in the field as electrical biomedians, or just simply biomedians. This is something that we can measure. We can use electrodes to measure the biomedians of a tissue or a sink of a whole body. And from that we can obtain some interesting data. We can characterize tissues, so we can differentiate some specific tissues. And we can also monitor tissues. How monitor, for example, evolves with a certain pathology. And this is basically what I did in the past. This is what I did during my PhD. In particular, what I was doing when I was doing my PhD was to monitor impedance of tissues. In the context of organ transplantation, the idea was that when the organs are harvested, the organs start to suffer, because they are not supplied with blood. And we wanted to monitor that suffering. We wanted to monitor how they are damaged. So we used impedance for that. What happens is that when there is this suffering of the tissue, basically the cells start to increase, and this compresses the solar space, and the impedance at low magnitudes increases. I also participated in a product development which was intended to do or actually realize, implemented a system for monitoring carriers or for detecting carriers based on impedance. This is the case of tissue characterization. So that belongs to the past, as I said. Now we are more interested in applying currents that have an effect, more than just looking at what happens in terms of passive properties. So again, we use the same model, the same circuit. And if we have two resistors here, we have two resistors that obey the Ohm's law, what we have to expect is that power, electrical power is going to be lost here in the form of energy, in the form, sorry, of heat. So this happens when we apply moderate currents for quite a long time. What we are going to have is significant heating. So warming the tissues up. This is what is known as joule heating. And this explains one of the adverse consequences of applying currents to living organisms. If you apply currents, excessive currents to living organisms, you are going to provoke burns. This is one of the less disgusting pictures I was able to get. So if we can kill tissues, we can use it. So we basically can use it for destroying tumors. And this is now a quite common technique in surgery. In the case of delivery, for example, it's quite complicated to excise a tumor, which is basically the first approach. It's going to be done. If you can excise it, do it, excise the tumor. But in some cases, it's not possible to excise the tumor. And delivery, in particular, is one of those areas where you typically don't, you cannot cut the tumor because it has a lot of musculature. So we are going to provoke a lot of problems. So it's better to try to kill the tumor to destroy the tumor. And in this case, heat is used by applying heat and cigarette. So we apply, or typically clinicians apply currents of frequencies about 40, sorry, 400 kilohertz and they burn the tissue. And this is something that can be performed just by inserting things from the exterior. You don't have to expose the liver. We go again to the model and we discuss what happens with these two resistors. You see here that we have this capacitor. So if we apply a pulse or a DC voltage, what is going to happen, and probably you also remember that from physics, what is going to happen is that voltage is going to start to build up across these two plates. The voltage is going to increase. And if the voltage is excessive, what may happen, once you have a dielectric, is what is called dielectric rupture. So the capacitor that we have here is not going to behave any more as a dielectric. It's not going to behave as an insulator, but it's going to start to conduct electricity. This is what happens. For example, you have two plates and you apply a very large voltage. We are talking about kilobolts. At some point, the air is going to start to conduct. This is what a spark is. This is dielectric rupture. In the case of living organisms, in the case of living cells, we have something similar. The physics is different, but we have this phenomenon of dielectric rupture. And this is what we call electroporation. It implies that we are going to have current going through these two plates, through this capacitor, through the membrane, but it also implies that molecules, which are quite large, can get into the cell and can get out of the cell. The membrane, which is normally sealing the interior of the cell, suddenly becomes quite permeable to molecules. More interesting than that is the fact that if this state of poration, this state of increased permeability, is not very severe, the cell is going to be able to recover after that transient permeabilization. So we have a mechanism to get things into the cell and have the cell be viable afterwards. This is typically used a lot in microbiology labs. In microbiology labs, they use this electroporation phenomenon in order to introduce DNA for transformation of the cells. I will talk a little bit more about that later. So I said that the phenomenon is not similar to the physics different from the dielectric rapture we have in the air or in other kind of dielectrics. The physics is still not completely understood. Let's say there is no agreement of what happens, but what it is believed to happen is that pores, actual holes, are being created in the membrane. What you see here are recent molecular dynamic simulations where the blue thing is the tails of the phospholipid layer of the membrane. This is like 5 nanometers and the red dots here and the white dots are water. What is subsurface simulation is that when you apply an electric field which is quite large, there are fingers that at some point join and create a channel. That's where pores start, where holes start. That's where the name comes from and the model that I just used now is quite simple. I said that we observe when we are applying low magnitudes but in reality the cells are a little bit more complicated than that. In particular what happens is that the interior of the cell is negative with respect to the exterior. This is something that is maintained in an active way. Cells are not only passive in electric terms but also active. We also have some structural structures in the membrane structures that are ionic channels which open and close according to the voltage that we have between the interior of the cell at that point. We have a combination of not only of passive properties but we also have active properties and we have nonlinear properties. This tries to model but this at the end explains what is an nerve impulse. The fact that we have cells that have this model for the membrane explains what happens with what we call excitable cells. Excitable cells are neurons which are in the brain or in the nerves and myocardial cells for example and these cells what they do or what they are able to do is to make a perturbation in voltage travel through their membrane. If for some reason the voltage in a segment of the membrane is perturbated beyond the threshold this perturbation is going to travel through the membrane. In the case of axons the axons are very long neurons actually they can be one meter or more. This perturbation is going to travel and this is what we call a nerve impulse. In general it is a nerve impulse in the domain of neurons. In general these waves these voltage waves are what we call action potentials. The interesting thing is that they typically are generated because there are some chemical transmitters, what are called neurotransmitters which have an impact on those switches that we have the protein channels that we have in the membrane that open or close them so that they cause the initial perturbation in voltage. But we can also initiate an action potential by delivering a current. So we have a mechanism for artificially generating action potentials for artificially generating something equivalent to pulses. So that allows us to do, let's say, neuroengineer. We can play with the nervous system. Of course this is something we can do for good but this is something that can also come from bad. This is also one of the mechanisms why people are electrocuted. If you mess with the heart rhythm because we apply currents you are going to kill the person. So all these things that I presented in both current to living organisms and currents are applying to living organisms biologically always through electrodes. So if we have two electrodes, typically metallic electrodes, in addition to all the things that I described we are also going to have electrochemistry. We are going to have electrochemical reactions, reduction of reactions or reduction of oxidation reactions at the electrodes, so at the interface between the electrode and the addition or the electrode that I said and the extracellular medium and also reactions in the middle. In the middle basically what is going to happen is that we are going to drag or pull the ions, the particles that have some charge. So these are reactions and this is what we can label in general as electrochemistry. So pills are basically the phenomena I discussed related to the delivery of currents to living organisms and I'm going to present the project that we have been working recently in that framework. The order is not the same because basically I want to talk more about what we have been doing recently on electroporation and on electrical estimation and this is going to be the large part of the talk. But just I'm going to use briefly two projects that we have been doing in these two domains, let's say. So what we have done regarding electrochemistry what we are doing regarding this domain is something very oriented toward a very specific application. Actually we can say that it's a product development which tries to solve a problem. A problem caused by clinicians. A problem caused when biopsies are taken. So in particular we are talking about prostate biopsies. This is something that unfortunately some of us will have to go through. So the idea is that when there is some suspicious that there may be prostate cancer, so biopsies need to be taken in order to do astrology and confirm the kind of cancer that we have. So basically what the clinician the orologist does is go with an ultrasound probe to visualize the prostate and once the prostate is identified the clinician goes with a biopsie gun, with a needle through the rectum and takes a sample from the prostate. The problem here is that bacteria which normally is confined within the rectum which is safe there meaning it's not causing any problem because the rectum, the wall of the rectum is a natural barrier to bacteria. Once we go with the biopsie needle, this is something that it's done a number of times, we cause a puncture of the rectum and this bacteria is going to go into tissues, it's going to go into the process and those are going to cause infections. This is something that the risk of that is minimized, the risk of infections minimized with bacteria, i.e. with antibiotics but even using antibiotics there is a significant rate of people being infected and this is a problem because we are talking about serious infections of people that has to be re-sputilized so these are cost, economic cost and this is also a safety issue these infections can be quite serious and life-threatening. So what we are proposing it's a mechanism to avoid that which basically consists on covering the biopsie needle with a thin layer of silver and then once the needle is inside the tissues releasing this silver by applying a current. So this current is going to release the silver into the tissues and this silver silver ions are going to combine with the chloride that naturally is within the tissues and that's going to form silver chloride and this silver chloride after the needle is removed is going to slowly release silver ions which are going to have an antibacterial effect. This is something that now we are doing quite extensive in vitro research and now we are moving into in vivo and to develop prototypes moving towards the clinical essence. This is something that we really want to push as a product. Now we switch to what we have been doing regarding your heating and this comes from basically this picture which it's about some reports that were in mass media actually and also in scientific reports a few years ago about a new technique, new modality for treating glioblastomas which is a kind of brain cancer which is has a very bad prognosis and the things this company which is of course related to our research group what they were claiming is that they were able to stop or slow the progression of glioblastomas by applying very low current. We are talking about currents that are supposed not to cause dual heating, are not supposed to cause electrochemical reactions, no electro-operation, no electrical stimulation so that's quite intriguing to anybody in the field and of course I was intrigued everybody in the field let's say bioelectrics and I did simple calculations to see if it was true what they said that there's no dual heating or significant dual heating because once you apply currents you for sure some dual heating and the dual heating that they were causing it was really mild but it was not, it was not zero the calculations show that we should expect an increase in temperature of about a few fractions of a degree or even a degree or two degrees so my concern or what I thought here they are doing some dual heating and this is a modality that's unusual because the treatments normally are last for a short period of time we typically apply treatments for minutes hours, no more than that and here we are dealing with a treatment in which the company and the research were proposing to be applied for weeks months so continuously so the idea was that the patient would be carrying always actually it's a treatment that is in use it's carrying always a backpack with a battery and with frequency generator for generating these fields they call two more treatment fields and then the that's the way they propose and this is unusual I said because normally treatments are applied for a short very short period of time and I speculated that maybe the fact that they were causing a mild heating over a long time was explaining the results they had because this was never tried I mean applying very mild heating for a long time as a cancer treatment modality was never used I put thermia so to increase the temperature with radio frequency fields or by other means it's used in oncology it's used in oncology but for moderate increases in temperature we're talking about 5 degrees increases and for short times this is something that is used in combination with chemotherapy it's known to be useful so there were some indications that these mild heating applied for a long time could be the reason why it was working slightly working and it could be helpful to realize that so basically it was basically pure speculation and that's why we asked to enter with Gabriela Capella from the Catalogoncology for one of those explorer grants because that was pure speculation and what we wanted to see is that if moderate temperature very mild temperature increase can help in terms of treating a tumor and at the same time to see if tumor treatment fields do something so basically what we did it was to implant subcutaneous subcutaneous will implant tumors in the back of mice and then to treat them to treat them either with pure hyperthermia very moderate or with tumor treatment fields with these low-magnitude fields tumors were pancreatic tumors from human origin and then what we combined also these treatments with chemotherapy, the standard chemotherapy applied for that kind of tumor and what we saw is that the hypothesis I have wasn't true at least in this model I mean the temperature alone increasing temperature alone didn't do anything without the drug or with the drug so there was no benefit in statistical terms the tumors basically were growing at the same rate treatment was applied for one week on the other hand by applying these tumor treatment fields although we didn't see anything when we were not applying the chemotherapy the chemotherapy drug we had a significant statistically significant reduction in the tumor growth, the rate of growth when we were applying the tumor treatment fields and the gencitabine which is the drug that is used the tumors were growing slowly it was not that we were killing the tumors, it was not that we were stopping them from growing, it was just that we were slowing them so for us this is intriguing because we don't know what is happening of course the company that is behind this product and the research team that is behind this product they have their own explanations because otherwise they could not get the FDA so they need explanations to justify why they are applying that but we have looked into that and to those explanations and the numbers simply don't make any sense so we still don't know what's going on think is that we would like to go into that but at the same time we are just slowing the tumor, we are not destroying and we will see now that with electroporation this is something that we can do we can destroy the tumor so we basically are more interested in continuing the work with electroporation it was just an exploration so what we do regarding electroporation and electrical stimulation which I think are the fields that are have more potential for collaboration within the department so electroporation, again electroporation is a phenomenon which describes an increase in the premaritality of the membrane to ions or even to large molecules when electrophils are applied to the cell to the living organism to the tissue so those fields are typically applied as short pulses, very short pulses 100 microseconds for example in order to prevent Joe heating so we are sure that we are not doing Joe heating or significant Joe heating and depending on the magnitude of these pulses and the way they are applied I mean the duration of the pulses and the frequency of those pulses but basically on the magnitude we can have either reversible or irreversible electroporation so reversible electroporation means that after a transient period in which the membrane is more permeable the membrane is going to reseal and the cell is going to be perfectly viable afterwards the cell is going to survive this allows us to introduce things into the cell as I said this allows us to introduce DNA and this as I said is used a lot in microbiology labs this is also started to be used in vivo for gene therapy and it is also used in what is called electrochemotherapy which is the introduction of a chemotherapy therapeutic agent therapeutic drug into the cell for destroying the cells that have been exposed to the electric field so this has huge applications but we are actually more interested in irreversible electroporation this is because of historical reasons because when I was at Berkeley basically at that lab they were starting to work on irreversible electroporation so applying high fields so that the cells will not survive as an ablation modality so as a method to destroy tissues a method to destroy tumors and why this is interesting this is interesting because although there are some other ablation techniques like video frequency ablation laser ablation, cryosurgery and microwave ablation although there are those other techniques all those other techniques are based on temperature changes are based on changing the temperature of tissues so basically they kill because they destroy the proteins and they not only destroy the proteins let's say of the cell itself but they also destroy the proteins that are surrounding the cell so this model that I was using assuming that the cell is just surrounded by an ionic solution is not valid anymore it has what is called a scaffold which surrounds the cell which is made of protein basically another molecules which create the mechanical structure of the tissue and it's very relevant, it's very important so electroporation is not destroying that electroporation is just destroying the cells which in a lot of cases is what we want to destroy we want to destroy the tumor cells we don't want to destroy the tissue itself so that's why there is a huge interest in that because that can mean that we can treat things that with other methods cannot be treated and we can prevent damage that is caused by the other techniques so that's what we are working on basically what we are doing is engineering on that and what kind of engineering we do one of the things that we do it's how to improve treatment planning of electroporation so electroporation for a specific protocol meaning a specific set a number of pulses a specific duration of the pulses that occurs in a point in the tissue where the elective field goes beyond the threshold so if we compute the electric field we can estimate in a configuration of the electros in a configuration of the tissue we can estimate which areas of the tissue are going to be killed and which areas are not going to be killed so we can do what it's called treatment planning this is a evolving field because we have to take into account the conductivities of the tissues changes because of electroporation and we are doing contributions in that sense we are doing contributions in the sense of how we can improve treatment planning not so much the tools for treatment planning but the models for treatment planning another thing that we do is to collaborate with biomedical teams in order to explore new applications for electroporation for irreversible electroporation this for instance is a study a few years ago with the group of Cristina Fijet at the time at the CRG now at EDBAPS and in which Cristina was interested in treating pancreatic cancers with viral vectors so I approached her regarding the use of irreversible electroporation and we started to see if we could do something for that and what we did it was to a safety study on the use of irreversible electroporation so what we did it was to implant now pancreatic tumors within the pancreas of mice we were able to see how those tumors were growing because the cells of the tumor also there are special genetically modified cells also emit light so we can basically with a very sensitive camera detect how the tumor is growing so when the tumor was large enough then we open let's say the mouse we expose the pancreas and we applied irreversible electroporation where the tumor was located where we thought the tumor was located and then in some cases actually a large number of cases the tumor was gone after a few weeks so that improved the overall survival of the animals very significantly but as I said what we were interested because we knew that we could get the result what we were basically interested in is a safety study we studied that by treating the pancreas we were not creating any other problems and this is something that it's already done, I mean this is already something that in clinics it's already in some very specific places electroporation is used as a way to treat pancreatic cancers where there are no other alternatives it's never the first approach until now so in the same line of collaboration with biomedical teams this is also a project which is ongoing a very ambitious project which is ongoing which starts with this slide this corresponds to a case in which tumors in a liver are spread a lot so we have a large number of tumors spread all over the tumor all over the liver sorry and this case in which if these tumors don't respond to chemotherapy there are a few options for treating them because basically we cannot excise them we cannot treat them locally it's one by one just by thermal methods or even by electroporation so Fernando Bordillo and surgeon at Hospital del Mar proposed to us could you consider to treat the whole liver instead of going tumor by tumor and then assume that we are going to destroy the tumors and not destroy the healthy liver okay we do that there is a slight change or slight difference in the conductivity of the tumors of the liver we do that what we find according to simulations that we are actually going to kill not only the tumors but we are also going to kill the tissues actually we're even going to kill more the healthy tissues than the tumors so that was no option but at the same time Dr. Bordillo noticed to us that the liver is a particular organ in terms of blood supply in the liver we not only have blood coming from the artery okay in this case the apoptic artery but we also have blood coming from the portal vein from the guts and the thing is that these ratios of irrigation let's say are true for the healthy liver but in the case of the tumors there is only blood coming from the apoptic artery so what we pose is to apply liquid with high conductivity saline solution this is sold okay through the portal vein so that we increase the conductivity of the healthy liver tissue without increasing the conductivity of the tumor tissue and by having this contrast in conductivity when we apply the field by applying a voltage across these two plates the field is going to concentrate on the tumors so we are going to destroy the tumors without destroying the healthy liver this sounds like quite reasonable simple idea in practical terms this is a maintenance this is one of the projects I will say that if it was proposed by an engineer the medical teams would say you are mad you don't know what surgery is but since it was proposed by a surgeon everything is fine so we can go ahead and it's very ambitious we are talking about people that has very bad prognosis there is nothing we can do with these people so the outcome would be very relevant and it's very ambitious in terms of all the things that we have to do in order to be able to implement that because of that we like that it's forcing us to do new things the other things that we discover is that when we started to apply large areas of delivery in which there was a tumor by two plates in this case it was easy it was very small so one of the things that we discovered is that those animals few minutes after applying the protocol by the pulses died at the beginning we were shocked because we expected that maybe during the delivery of the pulses because of the aromias caused by the pulses never happened we were not expecting such a sudden death minutes after the electroporation what we discovered is that by doing electroporation but destroying that large amount of tissue we are releasing a large amount of intracellular contents into the bloodstream in particular we are releasing a lot of potassium and potassium is known to be lethal because the concentration of potassium is too high in the bloodstream so basically we tried therapy in order to prevent the effect of potassium and actually also to reduce the effect of potassium and yes it worked we were able to minimize the number of animals dying actually we were reducing them a lot so this fact this phenomenon the fact that we are causing a lot of potassium and this can be lethal and it's relevant because clinicians that now are using irreversible electroporation are treating larger and larger tumors so our study serves as a warning note to those clinicians just to be aware that you have to monitor electrolytes because we here are causing a massive release of ionic contents from the interior of the cells another thing that this project is forcing us to do is to increase let's say the power of generators the generators we have been using the prototype we developed here and has been used for a long time and it's still used in terms of the voltage that it's applied and in terms of the current that we are able to apply it's very similar to the commercial generators that are now used in hospitals for doing irreversible electroporation so but that was not enough for doing this concept of trans-epatic electroporation it's something more powerful so basically we partnered with team experts on power electronics at the University of Tragosa and we have built something with much more advanced capabilities in terms of voltage and in terms of current and this what was intended for our own problem and now it's becoming something that it's useful for other people actually the companies that are producing the commercial systems for irreversible electroporation are connected with us because of this device this is a device that quite likely we are going to license to them because they are interested in being able to treat larger and larger volumes so yes the voltages we are talking about 3 kV the currents that we apply are large, look dangerous and are dangerous so we have to be careful so last topic I'm going to talk about what we do in this domain in the domain of electrical stimulation I'm starting just with a video which is from a group which has nothing to do with us this is our research, what was in mass media 2 years ago so maybe you saw that in TV or another place and what these guys did it was to implant electrodes on the brain of a patient which was completely paralyzed so she can only move the muscles of the head and basically by thinking about movement and by implementing borrow sophisticated learning algorithms these guys were able to send comments to robotic arm to move whatever she wanted to move in this case she is holding and taking a bottle of water this is quite impressive the amount of decoding this was really on the the electrodes were in the areas related to movement and they had to decode those more intentions this is quite amazing but you can see that she will look really happy the practical prospects of that are very limited we are talking about robotic arm we are talking about implants on the brain which are invasive in addition to that you have to take into account that those electrodes are not going to last for a long time yes it's very nice but it's not practical it's not going to be practical in the next years for sure so this cartoon illustrates what we saw this paradigm of having signals from the brain being decoded and being sent to a robotic arm and the question here is why not to interface directly with human muscles in the case of patients with paralysis most of the cases the muscles are perfectly okay so we in principle can stimulate those muscles actually the nerves that go to those muscles we can stimulate those nerves for performing movement I mean to create movement so why not to use the muscles which is going to be better for a lot of reasons cosmetic reasons for health reasons for a batch number of reasons so the short answer is that we don't have the technological means to do that okay we can do electrical stimulation of things that are let's say very close but when we have to perform electrical stimulation of points that are spread over a large portion of the body then we have a problem we have a problem related to the invasiveness of the method of the electronics we have to put there so I'm just stating again the problem here and what typically is done now in order to electrical stimulation the systems that we now we have for electrical stimulation the brain stimulation spinal cord stimulation the systems that are based on delivery currents to excitable tissues basically consist of a relatively large unit which is implanted subcutaneously and then this system is wired to the electrodes that perform the stimulation that deliver the currents to the tissue so that works nicely as I said for things that are not very spread to the body okay if we have to act on this muscle here and this muscle here and this muscle here we will need a large number of wires and this is going to make the surgery very complex okay and very in basic so in this case for solving that in the 90s it was proposed a new paradigm which was to develop single channel wireless microstimulators which could be deployed at different size okay by just minimally invasive procedures very similar to injection rather than surgery and those microstimulators okay that's a single channel so they already contained the two electrodes needed for performing for delivering the current these would be those I'm sorry would form a quite dense network which will be controlled by an external unit okay and the external unit would be able to send the signals to each one of those stimulators to activate them or to deactivate them so in order to be able to create quite complex movement patterns so the idea was nice it was neat actually but the problem is that the implementation was not really successful and it was not really successful because the implants that were developed according to this paradigm were two large, were two large and more than large they had quite significant diameter they may look large small for you they are large for implantation more than that they were rigid mechanically rigid so they were quite in basic shape so at the end only like five or four of those implants were deployed in a patient so this concept of a dense network of implants was never developed so what we are proposing is to improve this idea what we are proposing is to develop microstimulators which are going basically to look like what you see here a flexible short piece of flexible thread okay in which there are going to be two electrodes at opposite ends and then a small electronic piece in the middle or wherever you want here in the action because of that feature because of the way they look and because of their functionality we call them the name electronic axons e-axons and the thing here is well how this is possible well the limitation of those two devices is that they were either powered by batteries or they were powered by in that decoupling both cases which implies large bulky pieces which have to be integrated within the implant and that was the problem that was why these technologies were not reduced okay in terms of size here what we are proposing is something completely different what we propose is that the implants rather than using coils or batteries what are we going to do is to rectify currents okay what we are going to do is to apply high frequencies through the tissues where the implants are located okay and then the implants are going to rectify those currents what's going on here so we apply the high frequency currents like that okay so we are talking about frequencies beyond one megahertz not so high frequency and then apply it in short episode bursts because they are high frequency they don't cause stimulation okay remember the capacitor okay the membrane acts basically as a low pass filter so excitable cells don't feel high frequencies in other words and because they are applied in short episodes they don't hit the tissue so basically those currents are inoculus they don't do anything the tissues on the other hand the implants what are we going to do is to rectify so we are going to get these great peaks here okay and this is equivalent if we look at the low frequency contents to a pulse signal and those pulses are able to stimulate so now we are saying that we are generating pulses about 10 hertz or 100 hertz depending on the frequency of those pulse so basically we have a means for generating low frequency currents from high frequency currents and the nice thing here why we can't make these things very thin very flexible is that the other cases they were using coils they were using batteries in this case we are only using electronics okay rectification is a matter of electronics so this can be reduced a lot this can be integrated in a single integrated circuit so something very tiny and we are working in that direction so this is something that we would like to develop of course this needs huge resources okay which we are struggling to get them but in the meantime we are providing new evidences that this idea this concept it's doable it's feasible so different so sorry this is the way the external system would look like okay we still would have implants within the body and externally we would apply by means of an external control which would also contain a battery this system this external would contain a battery and would generate a frequency current and the commands to the implants and those commands and that high frequency current would be delivered through textile electrodes textile electrodes because basically we are dealing with high frequency signals okay so from the exterior also cosmetically appealing so I said that we are working towards providing evidence that the method makes sense well the first thing that we did it was to implant a diode okay which is the simplest rectifier you can think about in an earthworm okay and we showed that yes the system is able to perform a stimulation where the diode is located and it's not doing anything else where the diode is not located but the diode serves as a proof of concept but the diode it's not practical for clinical applications it's not practical because not only we are going to generate those low frequency signals at 10 hertz but we are also going to generate a DC component okay a continuous component component at 0 hertz so this 0 hertz signal this continuous signal it's going to cause electrochemical reactions okay it's going to cause electrochemical reactions at the electrodes which are going to damage both the electrodes and the tissues okay so what we did recently it was to improve this idea of the diode basically what we did this was to the diode we added a capacitor here is split into two capacitors just for geometrical convenience and a resistor so that we blocked the DC component so now the system is not generating DC components but it's still generating low frequency currents able to cause stimulation okay and this is the prototype you see that it looks much less invasive than previous system and we tried it I mean we did in vivo experiments with it basically what we did it was to connect it in rabbits basically we went with a catheter so the catheter contains a stainless needle to introduce the catheter and we used that needle in order to locate the point where we wanted to perform a stimulation for the movement we wanted to achieve okay so we are applying an external generator to locate that point so once we located that point we removed the needle and we introduced the stimulator and this is how the stimulator the micro stimulator looks once inserted okay this is an x-ray image again I'm going to continue describing the experiment so what we did it was either to implant those devices in the gastrocnemius muscle basically this muscle here or in the tblis muscle which is the muscle we have here in front okay and with that the idea was to obtain two different kind of movements either plant inflection which is called plant inflection okay so depending where the implant was located we would get one movement or the other movement then we applied high frequency signals okay or high frequency signals in order to be rectified by the implants this is the setup how it looks like we used a force measurement system and these are some force recordings these are force recordings for the casing which we have the implant here at the tblis this is just to show that the force recordings that we get by doing this rectification are equivalent to the force recordings we would have if we were doing direct stimulation of the muscle with conventional pulses this is what it's basically to say what you see here is the 20 episodes of high frequency when they are applied at quite low frequency we induce individual twitches of the muscle so it's called individual twitch okay once we reduce the frequency those twitches are fused and they create a larger contraction now you are going to see a video that working okay so in this case you barely are going to see any movement because you are only going to see the contraction of the muscle because the leg is anchored okay so you are going to see here the contraction happening okay so those were 10 bars applied at 10 hertz so since one day later this study was performed for 4 weeks okay the animals were not anesthetized during the 4 weeks only during these experiments okay as here you see that by increasing the frequency you only see a single contraction and it looks more stronger and stronger okay and now just for this situation you are going to see an experiment in which the leg was free to move it's in the other muscle before it was in the gastrocnemius muscle the posterior now it's in the frontal muscle so you see a single contraction applying quite large frequency and now you are going to see 10 individual contractions okay so that's nice okay we have a system that it's able to perform stimulation inside tissues in a very specific place where we put the implant and which can be deployed in a minimally invasive way it's something that we expect is going to be used for different applications of electrical stimulation which are not related with paralysis for example this principle could be used for pain I mean there is some kind of pain related to the nerves which is related to some malfunctioning of the nerve which can be prevented or avoided by performing electrical stimulation but you have to be very selective you have to be very close to the nerve so in that sense we think the system can work but we are let's say more ambitious than that we want to be able to stimulate at different points at the time we want to perform stimulation so we want to create complex movements we are aiming this paralysis approach so for that we need something more intelligent same to external electrodes we can command each one of the implants we can activate implant 1 we can deactivate implant 1 then activate number 2 immediately activate number 3 etc so to perform kind of movement patterns and we are working towards that since we cannot afford the development of an integrated circuit what we have done it's a prototype made with off-the-shelf components that you can buy in an electronic shop we are talking about very tiny components and this is a prototype we recently implemented you see here it's semi-flexible it's semi-rigid basically it's mounted on a semi-rigid printed circuit board and it's encapsulated with silicone so this is a proof of concept prototype this is not going to be usable for long times and what this circuit contains here okay this is quite complex is what you see here what we have here it's digital unit in this case a microcontroller probably the smallest available in the market which by means of a demodulator receives comments so here notice that we only have 2 electrodes so in the high frequency signal that we are sending through the tissues and the comments we encode addresses of the implant we want to activate so it demodulates this thing and according to what it's received it decides whether or not to activate the current sources that it has it decides whether or not to allow current to go that way or that way so we developed that and we also tried that thing recently in this case we did a study which was very similar to the study that you just saw but in this case instead of implanting the implant in one muscle or in the other muscle what we did was to implant at the same time two implants one in the tblis and another one in the gastroemius and these two movements the dorsiflexion or the plant deflection are going to be achieved by addressing either this one or by addressing this one this is what you are going to see now in a video the video is quite short it's not the best video that we could produce because you are only going to see a twitch of the leg so what we are going to do is to send a comment we have a virtual instrument with a click we set this implant or we select this implant and this is what you are going to see here so pay attention to the leg so here you see one of the movements it's a single twitch so that's why it's so fast and then the other one it's a low speed so it's a little bit clearer so these are very reasonable results not yet published so and that's basically what I wanted to tell you about and I need first before concluding to thank all the members of my team all the PhD students in particular I'd like to thank KinkasTV and Laura for the tremendous work that they have been doing all these projects that you have seen and of course all the past members of the group which include even undergrad students and all our collaborators external collaborators and the agencies that funded our research and thanks to you for being here thank you question yeah yeah yeah there's this I'll be sorry it's related to I think what was the second part the fixed 완�ord what they did they claimed that there was no temperature increase and what they did is would measure the temperature just beneath the external electrodes they had this helmet with electrodes and they measured and they said that there was no temperature increase and the temperature increase because of the fact that you were covering so they insist a lot but if you talk about clinicians that are using this technique they say no no there is something there is some heating there okay so there is some heating it's very mild and we that's that's also true it's very mild that is not going to do anything normally to tissues that that heating okay it's not going they barely to feel it yet and they did that and they do that and actually and they in the in the in some of the prototypes I think they have temperature measurement systems there to be sure that they are not increasing the temperature too much and then to switch off the the electronics so yes there is an increase in temperature that's a very good question the yeah the command thing it's a come it's it's what we are proposing basically it's an actuation system of course but you need to be able to send the comments okay one idea would be to get the signals from the brain okay but another idea which I find it's more interesting is to use over devices to measure signals what I mean in in a lot of patients what happens or amputees what happens is that you have some nerves that go through some muscles that are barely used okay those muscles are barely used and those are sending signals to those muscles and the to pick up the the signals from the nerves that is very challenging okay because the voltages there are very very tiny okay the voltages to the core signals from from an error it's something that can be done but in clinical applications it's barely seen because it's the signals are so small and you have so many noise around the body that it's very difficult to distinguish those signals so there's an interesting concept which was introduced a few years ago which is called targeted brain innovation and this this concept is basically the following so you have some nerves that go through some muscles that you barely use or for example are the nerves that went through a member that was amputee okay but it's not ever there so basically what they do it's to take those nerves we're talking about surgery and then to deploy them into the bacterial muscles which you don't use and then the nerves are going to innervate those muscles okay so what that does is to so the muscle then it's going to contract when you think about moving your arm or whatever you think and what is happening here is that what before it was very tricky to measure what before it was very tricky to detect from the nerves now it's very easy and now it's very easy because the the the signals from the muscles are very powerful okay the electrical signals from the nerves are very tiny are polluted with noise but the signals from the muscles are very very strong so here the idea one of the ideas we have is to use our systems to detect those signals from the muscles and then to relay those signals to another implant that would be one of the approaches we would have for that and this is something that our technology allows to do and one of the benefits of our technologies that it's minimally invasive we already have the two electrodes so we can pick up the signals and we already have tried not only downlink communication but also uplink communications we still have not recorded EMG of the muscle the signals from the muscles this is something we will work with that's an interesting question well that's basically the reason why we want to do something very thin I mean what's why we were interested in something that is very small and it's really easy to implant because there are systems I mean that are able to control a few number of muscles okay but the problem I said is difficult to implant them so we have the number of channels we have let's say it's very limited so the idea of the technology we are proposing is that we are going to be able to massively implant them so we are going to have hundreds of channels and it's maybe an accessory but 10s or 100 channels so now we are going to have not only one implant one channel per muscle even for the hand but maybe two or three infants per muscle and this is important because one of the problems with with muscle stimulation by electrical means is that you don't have good control okay you basically stimulate or not stimulate so by having three or four let's say implants per muscle we are going to be able to stimulate different portions of the muscle so we are going to be able to create the force that we apply in a better way we are going to have more control that's the reason why it's basically the reason why we're interested in something very thin very very easy to implant so the answer is 11 so no you notice we we probe the muscle to locate the point where we want to perform the stimulation and then we implant them the if we implant them properly which means that the implant it's all the length of the implant is within the muscle they don't move I mean that's the result of the experimental study we performed a few one year ago in which we basically had an implant what was properly implanted and through the whole study for a month didn't move at all okay that's one thing so but you're right I mean even if we have this probing method it's going to be very tricky to really put the implant wherever we want it specifically so the idea is that one of the reasons we are also interested in in a planting a large number of them it's to not taking care of that I mean just to implant them and then try them to see experiments so try number one number two and then to see the result in terms of movement and from that design the control algorithm so one of the ideas why we are interested in in planting them in an large number is not to be I mean not to be careful with where we implant them but to test them and from that knowledge then to decide afterwards which is the protocol we are going to use in order to create an specific movement or another movement that's one of the reasons why so to allow them to move that's not a good idea because if they move out of the muscle okay basically we implant them inside the muscle and we implant them inside the muscle close to a nerve okay with the nerve that basically acts on that muscle so if we implant them out of the muscle they will bend they would break after a while okay so we don't want them to move the case of the brain that would be different of course that's our technology that could also be applied for the brain but we are still not considering yeah well definitely it links to research in other groups is when I was talking about electrocution I was saying we are interested in freedom of planning tools this for sure it's an area in which there is a lot of overlap with other people in the department and this is something that we tried okay in the past it didn't didn't happen because of a number of reasons but this is something that we are we're still interested in these these things and in terms of this implant now we are proposing for for paralysis of course this is all the field of biomechanics and rehabilitation that people working here so that's something that is also of interest for us and in general whatever we are we are basically engineers electrically engineers delivering currents we are not experts on children planning we are not experts in numerical tools we use them we do things with them it's not our main focus is not yeah it's basically the case of what's called neuropathic pain okay so it's pain that it's rated in a lot of cases is rated with actually with cancer treatments when chemotherapy to perform this happens a lot because basically you damage a nerve and the nerve starts to do strange things and one of the things that is going to do is to send wrong signals like pain signals so in that case it has been observed that applying in stimulation which principle it's not completely understood why but applying a stimulation helps okay helps in terms of pain okay it's applied at peripheral nerves particularly in in the head nerves on occipital nerve but it's also applied at the level of the spinal cord okay if it overall trots are placed there for pain there's a huge controversy about that because when you are dealing with pain the placebo effect is always very important okay and here we are talking about the patients in which you are implanting a device with highly invasive surgery device that sometimes is super expensive so the placebo effect it's very powerful so there is still the debate whether it's real or it's not real what we know that it helps how it helps there is there is debate about that but yes we are talking about neuropathic pain or phantom pain in some cases the basic neuropathic pain because of damage to nerves that's very right. Thanks a lot Tony. Thank you.