Coin-sized wearable shows potential to boost biosensing

The discovery by a team at The University of Hong Kong (HKU) featured on the April 2022 cover of Analytical Chemistry.

The PERfECT System –Personalised Electronic Reader for Electrochemical Transistors – is claimed to be the world’s smallest of its kind, measuring 1.5cm x 1.5cm x 0.2cm and weighing 0.4g. The wearable device can be integrated with a smartwatch or patch to allow for continuous monitoring of biosignals such as glucose levels and antibody concentrations in blood and even sweat.

“Our wearable system is tiny, soft and imperceptible to wearers, and it can do continuous monitoring of our body condition. These features mean it has the potential to revolutionise healthcare technology,” said Dr Shiming Zhang of the Department of Electrical and Electronic Engineering, who led the HKU WISE (wearable, intelligent and soft electronics) Research Group.

HKU believes the technology marks advance for organic electrochemical transistors, which are widely considered to be the next-generation sensing technology because of their water stability and high sensitivity at low operating voltage (milli-volts) but which, until now, lacked a miniaturised wireless system to operate within.

The PERfECT wearable precisely characterises the overall performance of the electrochemical transistor with a data sampling rate as high as 200kS/s, which is said to be comparable to bulky commercial equipment but at one-tenth of the price.  It can also serve as a miniaturised electrochemical station for wearable devices and measure the outputs of other kinds of low-voltage transistors, such as electrolyte-gated field effect transistors and high-k dielectric-gated thin-film transistors.

The system could be applied immediately in multiple wearable systems that are based on low-voltage transistors. Dr Zhang’s group has formed a start-up company, SESIC, to make the technology accessible.

“We have been able to develop the PERfECT system because of the unique, interdisciplinary culture in the HKU WISE Research Group, which includes researchers from electrical engineering, applied chemistry, biomedical engineering, microelectronics and software engineering,” said Dr Zhang. “The vision for WISE is to promote the transition from ‘hospital-centric’ to ‘human-centric’ healthcare by developing next-generation wearable, intelligent and soft electronics technologies – hence the name WISE.”