HKU Bulletin November 2022 (Vol. 24 No.1)

Wearable devices like the Apple Watch can track your blood rate and blood oxygen levels and detect whether you fall. But to researchers of wearable devices, this is old hat. “Those kinds of devices were developed more than 10 years ago. Some researchers are still working on improving sensors for physical signals but the field that is very hot right now is detecting biochemical signals within our body. Imagine using your smartwatch to sense your glucose level, that would be very useful for diabetic people,” said Dr Lin Haisong, Research Assistant Professor in the Department of Mechanical Engineering. Dr Lin is in the thick of these advances, having recently developed what he calls a ferrobotic digital microfluidic platform, that can read and detect various kinds of biochemical signals, such as glucose, viruses, immunological health markers, nutrient levels and stress hormones, from our saliva, sweat, urine or blood. And it does not have to be worn – people could simply press their finger on it. The platform takes droplets of bodily fluids and divides them into tiny volumes so they can be tested by a variety of biological assays. The latter are add-ons to the platform that can be developed by other specialists, similar to software for a computer, to help create a tool for highly personalised medicine. Thermometer for everything “When we talk about the human-machine interface in the field of biosensing, sensing biochemicals within our body is not limited to wearable devices. In fact, we already do things like rapid antigen tests that are an example of biosensing. “We are using microfluidic technology to try to create small devices that hopefully could be deployed for various purposes. For instance, a doctor or researcher would just have to put the sample into our platform and the answer would come out. Currently, laboratories have to spend time pipetting and processing samples under the microscope and centrifuge and it can take several hours,” he said. Dr Lin envisions that the platform could even sit alongside personal computers and people could purchase applications that produce readings of parameters that are important to them. They could check whether their stress hormones are high indicating they should rest, take their temperature, or do HIV or pregnancy tests and the like, all on this one device. It would be like having a thermometer for everything. The first findings on this platform have already been published and work is underway on the next generation. The potential for detecting viruses, such as COVID-19, is obviously attracting a lot of attention. “Our platform can sense COVID-19 very efficiently, I’d say at least 10 times more efficiently than current technological agents,” he said. A question of when, not if Although there are still some challenges, such as sorting out materials compatibility, Dr Lin believes the endgame is in sight for making devices like his platform widely available. “I’m very confident they will be in use within 10 years or less. It’s just a question of whether I will be the person who makes it happen. A lot of people are working on this,” he said. “After COVID-19, we all know how important this data and monitoring technology are.” Dr Lin has one advantage in the race to develop his platform in that he is motivated not only by science but by a desire to help other beings, be they human or animal. He was first inspired to work on sensing technology when he was working at the University of California, Los Angeles. His laboratory was close to the university hospital, and he noticed cerebral palsy patients who were unable to talk. “I wanted to find a way to help them communicate their pain and discomfort,” he said. Later, he realised sensing technology could also help animals after a friend’s dog died of cancer within a week of diagnosis; the friend was upset as they were aware the pet had been in pain. “I feel this field of biosensing and microfluidics and bioelectronics is going to play a huge role in the future and benefit not only humans, but also some animals,” he added. READING OUR BODIES Researchers are not far from the day when they can produce a small desktop device that can read our biochemical signals and tell us the state of our physical and even mental health within minutes. Dr Lin Haisong is among those making advances in the field. The application of wearable microfluidic system for glucose and lactate monitoring in sweat. A ferrobotic microfluidic chip for automated biochemical sample processing and biomarkers detection. DR LIN HAISONG I feel this field of biosensing and microfluidics and bioelectronics is going to play a huge role in the future and benefit not only humans, but also some animals. COVER STORY 10 11 The University of Hong Kong Bulletin | November 2022