We’ve previously covered a variety of adhesive sensors that measure internal biomarkers — such as body temperature or heart rate — while affixed to the skin. Now researchers at the University of Tokyo have developed a skin sensor that detects stimuli from outside the body: pressure, to be specific. The ultra-thin sensor was created to record the mechanics of how hands manipulate objects, perform tasks, and interact with the environment.
The research team faced a design challenge because they needed a precision pressure sensor that wouldn’t interfere with the heightened sensitivity of human fingertips. To create a sensor that the wearer essentially cannot feel, the team built a novel material called a nanomesh sensor. This material was fabricated through a process called “electrospinning.”
Electrospinning uses a high-voltage electric field to charge a polymer solution and other nanoparticles. The voltage then forces these components through a tiny spinneret, so they combine to form a network of ultrafine fibers. The University of Tokyo engineers spun two separate layers; a polyurethane layer that’s 500 times thinner than a human hair serves as insulation for the electronic sensor layer. This electronic layer is spun from gold microfibers in a polymer solution that dissolves after manufacture; it can detect both pressure and movement.
Testing on 18 research subjects showed that the sensor is surprisingly durable even though it is made up of fine structures. It sustained no damage and maintained accurate recordings despite the presence of significant external friction. Because the sensor has minimal impact on sensitivity and the ability to grip objects, users were able perform intricate tasks without interference while wearing the device. The team published the results of their study in the journal Science in November.
The team hopes that the new sensor may prove useful in digitally archiving an artisanal craftsperson’s delicate handiwork or a highly skilled surgeon’s subtle hand motions. It might benefit studies in the fields of sports medicine and other medical specialties. The sensor might also offer granular environmental feedback that could make movement more natural and functional in smart prosthetic and robotic applications.