Paper Review Highlights Progress in Flexible, Strechable Electrochemical Biosensors for Healthcare

A team of researchers from Chongqing University, Beihang University, The Pennsylvania State University, and Huazhong University of Science and Technology have released a paper detailing recent developments in flexible and stretchable bio-sensors — and Penn State thinks it might be close to a breakthrough.

Placing smart devices within the human body comes with a key problem: Transmitting and receiving data. A radio with an antenna is an obvious solution, but the properties that make for a good antenna aren't the same properties that make for a good implantable device. Soft, stretchable antennas are better — but designing them requires a lot of computational power.

"We explore a lot of different patterns and designs when we are investigating these ideas, but this can create more parameters," says Penn State Professor Larry Cheng of his team's work in the field. "This can become a problem because it’s difficult to find the right design with all of the different parameters. That’s why we need more computational power — this additional computational power can help us play with the different parameters and find out the effect of each one. Then we can figure out how to optimise them.

"We need to leverage the computational resources to design this efficient antenna that can be stretchable, but, more importantly, with this stretchable antenna, we can do a lot of things because if we want to get the place where these sensors are transmitting data, this antenna is the key element that you can’t get around."

Another issue with implantable or even wearable electronics is power: Batteries are big, bulky, and typically rigid. Cheng's solution: Energy harvesting. "Our work now is also focused on harvesting the ambient energy, which can include Wi-Fi, the 3G, 4G or 5G, or even microwave sources," Cheng says. "With ambient energy, it’s always on, no matter whether you’re using it or not, it’s there.

"Even when you go to sleep, it’s there. If we don’t harvest that energy, it just gets wasted. If we only harvested the energy at a single frequency, it will, of course, minimize the amount of energy we can use, but by harvesting the energy over a wide band around the device, it will compound the efficiency."

The work of Cheng's team at Penn State is being investigated for biosensors used both within the human body and worn outside it, including bandages that can monitor wounds as they heal and temporary tattoos that can monitor a patient's glucose levels. This work, and the work of other teams found around the globe, is summarised in the mini-review paper published in the journal Micromachines under open-access terms.