 I've been working in the Float Clinic and Research Center at the Laureate Institute for Brain Research since I joined the lab as an engineering intern about four years ago. My presentation will cover my main contribution to the lab, the research and development of a hand dynamometer, which we like to call the squeeze ball, and a novel research environment, which we like to call the float tank. So a little bit about me, when I was a junior electrical engineering student, the main career paths ahead of me in Tulsa are usually either oil and gas or aerospace, which are exciting but not exactly my cup of tea. So Justin Feinstein came to the engineering department with an interesting presentation. He was looking to build a float center, a research float center in Tulsa, and he needed engineering support. So my first thought was, what the heck is a float? And my second thought was, that's interesting. Sign me up. How do I get on board? So I met up with Justin after the presentation was over, and then I joined the lab as an intern, and I had no idea what I was getting myself into. And I know that you all see those stars and know what those mean. This is my third presentation, and I'm so excited to be up here on the stage. So before we can get into the development of the squeeze ball, we need to learn more about cardiac interoception and our hypothesis on the perception of the heart and why it is so important, especially in the float tank. Once we know exactly what biological signals we want to measure, I'll take us through the process of the hardware and the software development that makes it happen. And finally a conclusion that shares some preliminary results from the squeeze ball. So cardiac interoception, we'll take this word apart. Cardiac is relating to the heart. So out of all the wonderful organs in the body, we're going to be focusing on the heart. And then intero is relating to your internal body, your internal sensations. Andception would be your awareness or your perception. So we put it all together. Cardiac interoception is to feel and understand your heart. We can dive a little bit deeper and look at accuracy, which would be the hit or miss in recognizing a heartbeat, and then precision, which would be how quickly you can perceive that heartbeat. So why cardiac interoception? Because performance is affected by mental health. Anxiety, depression, PTSD all have some influence on how the heart is perceived. The float tank is a perfect environment to measure this because in the floating environment your heart more easily enters your awareness. It could be the flow of blood from your heart to your extremities, or it could be your ability to hear your heartbeat reverberate through the water. Over the course of a float, a single float, or multiple floats of mental health changes, we also want to monitor the perception of their heart to see if that changes as well. Our hypothesis is that we predict that floating exposes and reinforces pathways used for cardiac interoception and will be evident in increased cardiac interoceptive performance. Also to measure cardiac interoception, we need two data streams. The first data stream is when your heart is actually beating, and we can determine that through an electrical cardiogram, or ECG, and then we'll need response, which will come through in the form of squeezes. So we put those two together, and that's all we need. And so for accuracy, we would look at the data, we'd see a heartbeat, and we'd see if there's a squeeze that follows it. For precision, we would measure the time delay between the heartbeat and the recognition. So into the experiment. This will put the physical limitations on the device. We can't have any devices to be wired, because if someone's trying to float around and be free, we don't want to anchor them down, and the devices have to be safe. It would be bad if we were to shock the people we were trying to help. And of course it has to survive the float environment. One little drop of salt water can just kill electronics. We even have a, I've been maintaining a sort of graveyard. Every time a piece of equipment fails or gets salty, it goes into the graveyard. And as someone float, we spend so much time to sound proof these rooms, to lie proof these rooms, to remove as much stimuli as possible. So how tragic would it be if we put a device on something that lights up or that vibrates, and then we ruin the float experience and we destroy the measures that we're hoping to take? So when we design devices and look for devices, we have to think about how the device is going to impact the float experience, or more precisely, how it does not. And for collecting ECG, a commercial device exists called the Biopatch. It sticks onto your chest with two electrodes near your heart, and it needs a little modification, a little adaptation to survive the float tank. So we put a waterproof protective layer, and it also has some lights. So we put tape on the lights, so that way the subject isn't woken up by flashing lights during the float. But for the squeeze response data, no devices existed. So with my understanding of cardiac interception and the floating environment, I designed and built the squeeze ball. So of course, waterproof and salt proof, it has to survive being used, survive being cleaned, survive being dropped, survive being handled roughly. For the signal attenuation, if I were to take your cell phone, waterproof it and slowly lower it into the float pool, you lose your Bluetooth, you lose your Wi-Fi, you lose your cellular data. So if we're trying to send signals back and forth out of the float tank, we need to make sure those signals are strong enough to get out of the float tank. And then battery life, efficient power use, so that way we're collecting data throughout the entire experiment. And last would be a sensitive pressure recording circuit, so while the subject's floating and they're concentrating on their heart, we want them to maintain that concentration on their heart. So they only need to squeeze just a little bit to get that recognition across, because the more they squeeze, the more we're going to interrupt that float experience. And so the cute monster down there was the very first prototype. And after several revisions, we have the working models over there that are in use right now. And so here's just a little snip of data. We have our ECG in red and our squeeze data in blue. In red we have the 98th heartbeat, 99th, 100, 101st, and then we have the 18th squeeze, 19th, and the 20th. And here's a good way to look at the latency between heartbeats. So you have about one second from one heartbeat to the next, so the subject has about one second to respond to that heartbeat before the next one occurs. So we're on a very, very short time scale. And the two devices, the ECG, the biopatch, and the squeeze response data from the squeeze ball need an additional setup to synchronize their data. So imagine you and your friend just bought new watches and you set them at exactly the same time. No matter how quick you are, you can never get both clocks, both watches, to start at exactly the same time. And we have the same problem with the biopatch and the squeeze ball, because they both have their own clocks. So what we do is to wire both devices together, send time pulses to them. Once the experiment is done, once the data is collected, we can look at those time pulses and synchronize the device. Without synchronization, we have a zero to two second error. And so if we have heartbeats that happen every second, and our time error is two seconds, the data is just uncomparable. So here's another bit of data that's been synchronized. So we have a pair of a heartbeat occurring in red, and then the squeeze that follows it in blue. So the first one, we have a 241 millisecond delay for the second, 194 seconds for the next, 579, and then for the last one, 596. So with our devices working, with our synchronization working, we can flow participants and collect data through structured experiments. And so here's a very brief glimpse into some results from our current R34 study, the first NIH flip flood and study. We have our participant ID over there, what condition they're in, and then heartbeat detections during a one-minute heartbeat detection task. And I've included in here the dry float condition, which is very similar to the float. It's full of warm water, but it's inside of a plastic mattress. So the water keeps you buoyant, but the water never comes in contact with your skin. So we've dry float data, and then wet float data in the float tank. And included these, so that way we know the squeeze ball and the tile patch are working correctly in both conditions. So that way when we collect the rest of the half of our data sets, we'll be able to confidently analyze the data. So for the conclusion, cardiac interception is an attractive measurement for float research because of the increased heart sensations during a float and the relationship with mental illness. Devices created for the float tanks need special design to survive the environment and not interfere with the float. Time-sensitive measurements requires additional synchronization processes, and based on our preliminary results, our devices are working and collecting reliable data. And I'd like to thank everyone in our lab, Justin, myself, Cindy, McKenna, Laura, Hikyung, Obada, and Jessica. Jessica's not in this picture, but she was there in spirit. Oh, I want to thank you of all of you for coming out. That's awesome. You all are beautiful. And all of the interns and graduate students in the past, the president, and that will be there in the future. Thank you guys.