Technology ‘paves the way for biodegradable electronics’

A new kind of electronics technology that dissolves in water is paving the way for biodegradable electronics and temporary medical implants.

Researchers in the US have developed a way to make high-performance systems from ultra-thin sheets of silicon and soluble conductors, which could help reduce electronic waste from devices that are frequently replaced such as mobile phones.

The scientists from the University of Illinois, Tufts University and Northwestern University want to develop medical implants that function for a set period of time and then dissolve inside the body, eliminating the need for an operation to remove them.

They have already demonstrated a small device designed to monitor and prevent bacterial infection at surgical incisions by implanting it into a rat.

‘We refer to this type of technology as transient electronics,’ said research team leader Prof John Rogers, University of Illinois, in a statement. ‘From the earliest days of the electronics industry, a key design goal has been to build devices that last forever — with completely stable performance.

‘But if you think about the opposite possibility — devices that are engineered to physically disappear in a controlled and programmed manner — then other, completely different kinds of application opportunities open up.’

Another application of the technology could be the creation of wireless environmental monitoring sensors that could be deployed, for example, following a chemical spill and left to degrade once they’ve been used, without causing additional environmental damage.

The researchers have implanted a dissolvable chip in a rat.

The team has built transient transistors, diodes, wireless power coils, temperature and strain sensors, photodetectors, solar cells, radio oscillators and antennas, and even a 64-pixel digital camera.

All of the materials, including the conductors based on magnesium and magnesium oxide, are biocompatible and because they are extraordinarily thin they can dissolve in even minute volumes of water.

The researchers encapsulate the devices in silk, the structure of which determines the rate of dissolution — from minutes to, potentially, years.

‘The different applications that we are considering require different operating time frames,’ Rogers said. ‘A medical implant that is designed to deal with potential infections from surgical site incisions is only needed for a couple of weeks.

‘But for a consumer electronic device, you’d want it to stick around at least for a year or two. The ability to use materials science to engineer those time frames becomes a critical aspect in design.’

The researchers now plan to further develop the devices for specific applications, conduct more animal tests, and work with a semiconductor foundry to explore the possibility of high-volume manufacturing.