Flexible skin sensors have advantages over hard-cased wearables in terms of the potential for precision readings. But pliability has a disadvantage when it comes to the durability of bendable sensor hardware components. That vulnerability means that a flexible sensor becomes less reliable with each use. A research team from the National Institute of Singapore (NUS) has developed a new material for sensor construction to improve reliability.

Variation in reliability — known as hysteresis — affects the precision of long term data generated through the sensor. Without reliable accuracy, sensor data analysis can’t provide genuinely usable insights. That limits its ability to assess overall health, fitness, biomarkers of illness, and other concerns that wearable monitors are intended to address.

To maintain the high sensitivity of flexible skin sensors, researchers from the Institute for Health Innovation & Technology at NUS added metal to the elastic polymers used in many types of flexible sensors. The team designed a process that embeds minuscule rings of metal inside cracks in the surface of the polymer. Once integrated with electrodes and substrates, the resulting piezoresistive sensor remains pliable but is less susceptible to degradation caused by bending and touching.

The team documented the reduction in hysteresis through a series of mechanical tests. The results show the new sensor, known as Tactile Resistive Annularly Cracked E-Skin (TRACE), has five times the reliability of conventional piezoresistive skin sensors. The team published their findings in the journal Proceedings of the National Academy of Sciences in September.

TRACE offers enhanced accuracy for health monitoring applications. It also has promise for applications involving artificial intelligence–specifically robotic finger perception. The research team has ongoing projects planned to both improve the comfort of the sensor and to develop its AI capabilities. As a method of artificial perception, TRACE might have a meaningful impact on human prosthetic devices’ future trajectory.