Flexible Imperceptible Patch Brings New HMI for Humans and Robots

Researchers from the University of Houston have designed a wearable patch that translates human motions and other commands to a robotic counterpart, which can send feedback back to the wearer as well. The team was able to pack transistors, RRAM memory cells, UV light detectors, temperature sensors, strain sensors, and tiny heaters into the 4-micrometer-thick patch, which they claim is nearly imperceptible to the wearer, much like a Bandaid.

In a demonstration, a human user was shown moving their fingers while a robotic hand mimicked the same movement using data sent from the patch’s strain sensors. While performing those motions, the robotic hand sent back temperature information to the human using the built-in heater circuits. The metal-oxide-semiconductor nanomembrane could also be used as a prosthetic skin for a robotic hand that can relay back data to the wearer or in healthcare applications where physical contact is needed to identify physical conditions.

The researchers made the patch using photolithography and features 50-nanometer-thick gold conductors, indium zinc oxide (IZO) semiconductor, polyimide encapsulation, and a typical dielectric epoxy known as SU-8. The conductors have a serpentine shape that allows the patch to flex without breaking, but the IZO is the star of the show.

The material acts as a semiconductor with the transistors, and a photoconductor with the UV sensors. IZO’s resistance decreases with temperature, allowing it to act as a variable resistor in temperature and strain sensors. What’s more, different structural patterns of the material create specific voltages enabling it to incorporate RRAM into the flexible patch. The team recently released a aper that details the patch and its remarkable capabilities entitled “Metal oxide semiconductor nanomembrane–based soft unnoticeable multifunctional electronics for wearable human-machine interfaces.”