Bonding Rubber and Electrical Components for Soft Medical Sensors

Researchers at Imperial College London have developed a way to create a tight bond between rubber and electrical components.

The method could pave the way for a variety of soft sensors for medical applications. For instance, such sensors could provide a signal when squeezed or stretched, with potential in monitoring patient rehabilitation after hand injury, or functioning as respiration monitors by providing data on the expansion and contraction of the chest.

One of the major difficulties in developing such devices to date has been integrating electrical components smoothly and securely in soft substrates, such as rubber. This group of researchers has come up with a new approach to this problem. Their technique results in an incredibly strong bond between rubber and electrical components, and when tested to failure, the rubber itself will break before the bond will.

Previous attempts to bind rubber and plastic have involved adhesives or clamps, which either came apart under force, or damaged the soft material. This new approach involves metal-coated silicon that can chemically bond to the rubber, but that also features copper plates to which electrical components, such as wires, can be attached through soldering.

The new material has enormous potential in wearable healthcare sensors. “We hope this method will allow us to make low-cost soft sensors that are reliable and portable, that can be used to monitor people’s health in their own homes,” said Michael Kasimatis, a researcher involved in the study. “Such sensors could be coupled with a mobile device, such as a smartphone, so that the data they generate can be easily processed and stored on the cloud, which is important for applications in digital healthcare.”

So far, the researchers have made some prototype sensors, including a squeezable ball to monitor progress in hand rehabilitation, and a stretchy band that goes around the chest and monitors breathing. “Having successfully demonstrated how this new bonding approach could work and be applied in laboratory prototypes, we now want to take this technology out of the lab and make it available to everyone,” said Firat Güder, another researcher involved in the study.