 Imagine if this water full of algae was your drinking water supply. Alkal blooms are caused by tiny microscopic plants known as cyanobacteria or blue-green algae. They cause a host of problems including fish kills, food poisoning and even liver damage or paralysis. The annual economic cost of blooms runs into billions of dollyards. Algae thrive in fresh waters where there are excess nutrients, usually from nitrogen and phosphorus. We tend to have more nitrogen than phosphorus in freshwater environments and so phosphorus ends up being the limiting nutrient which controls the growth of algae. If we could detect phosphorus inputs early enough, perhaps we could prevent the bloom from happening. What we need is a real-time sensor for phosphorus, one that could tell us actual concentrations in the environment. That way we could pre-empt the bloom and fix the source of the problem. Wouldn't it be great to have an early warning system? However, the conventional way of measuring phosphorus is time-consuming and labor-intensive. First we have to grab a sample of water and bring it back to the lab. Next we have to filter it, process it before running it on an expensive piece of equipment. We also have to worry about changes in phosphorus during transport and where to store the sample. Enter our solution. Here we put together three key components. A concentrator to concentrate the phosphorus from the environment. A light detector to sense and quantify the amount of phosphorus. And a computer to collect the data for further processing and wireless transmission. Now we have a compact real-time phosphate sensor. The first component, the concentrator, works on the principle of diffusive gradients in thin films. The phosphorus target diffuses through a thin membrane and into a polymer solution which captures or binds the targets. The whole process is very fast and the concentrator is only this big in size. Next we have to measure the amount of captured phosphorus. This is done by adding a color reagent which changes the color of the solution according to how much phosphorus is present. We use two LED lights and a spectrophotometer to measure the change in light absorbance or color. The greater the change in absorbance, the greater the amount of phosphorus. Now we can put the whole system together. The concentrator to concentrate the phosphorus and the light detector to sense and quantify the amount of phosphorus. The whole detection process takes just less than a few minutes. So effectively we have a real-time sensor that can measure phosphorus. The data collected can then be transmitted wirelessly. So how does this compare to the conventional grab sample approach? In grab sampling it takes about two days to thoroughly clean and prepare the bottles for sampling. It takes another day or two or even three to bring the samples back to the lab and process them for measurement. All in all it takes about four to five days to get a result. But with our in-situ monitoring system there is now no need for all of that. Our device is sensitive, real-time and automated. Because it uses LED lights its parts are cheap and the power requirements are low. Data can be acquired onsite and transmitted wirelessly to your home or to your office. When we compare the different methods of measuring phosphorus our device is much cheaper than commercial instruments. We are looking at less than 3,000 for our system compared to more than 100,000 for a lab-based machine that does a similar job. Compared to portable spectrophotometers our device is also much more sensitive. However there are still some limitations that we have to overcome and these include interference from other substances in the water as well as biofouling of the membrane especially in tropical waters where things can grow very fast. These factors would tend to lower the sensitivity of our instrument and make it more difficult to measure phosphorus. Our plan is to couple the sensor to the NUS swan. This robotic swan could be programmed to swim across a lake to detect phosphorus and other pollutants. Our vision is to have smart management of our water resources. We send our swans to collect data on pollutants. The data is then fed back in real time to computer models which can predict algal blooms telling us when and where it is safe to swim or fish. The swans could even be used to deliver solutions right to where the problem is. Our sensor measures phosphorus but it can be reconfigured to measure other pollutants such as arsenic. Apart from protecting natural water resources our sensor could also be used to protect drinking water, agriculture and food supply. By providing early warning to pollution events we can better protect human and ecosystem health. Thank you.