Real-time health monitoring and sensing abilities of robots require soft electronics but a challenge of using such materials lies in their reliability. Unlike rigid devices, being elastic and pliable makes their performance less repeatable. The variation in reliability is known as hysteresis. Guided by the theory of contact mechanics, a team of researchers developed a sensor material that has significantly less hysteresis. This ability enables more accurate wearable health technology and robotic sensing.
When soft materials are used as compressive sensors, they usually face severe hysteresis issues. The soft sensor’s material properties can change in between repeated touches, which affects the reliability of the data. This makes it challenging to get accurate readouts every time, limiting the sensors’ possible applications.
The new material has high sensitivity but with an almost hysteresis-free performance. The team developed a process to crack metal thin films into desirable ring-shaped patterns on a flexible material called polydimethylsiloxane (PDMS). They integrated this metal/PDMS film with electrodes and substrates for a piezoresistive sensor and characterized its performance. They conducted repeated mechanical testing and verified that their design improved sensor performance.
The Tactile Resistive Annularly Cracked E-Skin (TRACE) sensor could potentially be used in robotics to perceive surface texture or in wearable health technology devices; for example, to measure blood flow in superficial arteries for health monitoring applications. The next step is to further improve the conformability of the material for different wearable applications and to develop artificial intelligence (AI) applications based on the sensors.
The long-term goal is to predict cardiovascular health in the form of a tiny, smart patch that is placed on human skin. Other applications include uses in prosthetics, where having a reliable skin interface allows for a more intelligent response.