Metal oxide thin films make wearable biosensors

Researchers at the University of California, Los Angeles, and the California NanoSystems Institute, have developed ultrathin, flexible, metal oxide semiconducting thin films for use in wearable or implantable biosensors. The devices, which are made using a straightforward printing technique, could be used as sensors in non-invasive health monitoring applications like smart contact lenses that monitor a person’s glucose levels, for example.


“Our work is at an early stage, but these devices might be used by people to check their daily health, and for early detection of specific diseases,” explains team member and lead author of the study You Seung Rim. “Smart contact lenses, for example, could be a non-invasive way to detect various molecules in tears and this information could then be relayed to smartphones and medical centres.”

The biosensors, developed by a team led by Yang Yang, Paul Weiss,Anne Andrews and Hsian-Rong Tseng, can be applied to tissues or organs or for “temporary tattoo” applications. They can be produced using cheap and readily available chemicals in a straightforward printing technology.

The researchers began by making water-based In2O3 precursor solutions to make high-quality In2O3 films around 3.5 nm thick over large surface areas. To make the biosensors, they coated these films on thin polymer (polyimide) films and then made field-effect transistors (FETs) from them.

“Our printed In2O3 FETs not only show high device performance but also have high sensitivity,” Yang tells “What is more, we can easily modify the exposed semiconducting channel regions in the devices with different chemicals so that they can detect molecules, such as glucose, at physiologically relevant concentrations.”

The team says that it is now busy trying to make even thinner biosensors that are more sensitive

and selective to different molecules. “We are also working on making biosensors that specifically detect different types of bacteria and viruses,” says Rim.

The present research is detailed in ACS Nano DOI: 10.1021/acsnano.5b05325.

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