This ultra-thin intelligent biosensor is also a powerful human-machine interface for new generation prostheses.
This is again an innovation from the California Institute of Technology (Caltech, Pasadena, California), this electronic skin or e-skin entirely powered by sweat and capable, like a classic tracker, of monitoring health. A real electronic detection platform therefore, presented in the journal Science Robotics but not only: this ultra-thin intelligent biosensor is also a powerful human-machine interface for new generation prostheses.

This is not the first patch – or e-skin – equipped with flexible sensors capable of monitoring several physical parameters. But it’s probably the first one that doesn’t need battery power or communication from a nearby magnetic field. The idea here is indeed the design of a tracker suitable for the next generation of robotic and medical devices, operating wirelessly and self-powered. Several research teams are currently working on devices that can recover energy from the human body.

 This flexible e-skin, entirely powered by sweat
and therefore without battery, is equipped with multimodal sensors and very efficient lactate biofuel cells which allow stable self-supply in the long term self-sufficient for a period of 60 hours. The device is capable of monitoring the main metabolic components or analytes (urea, glucose, pH, etc.) and of transmitting this data to the user interface via Bluetooth. The device is also capable of monitoring muscle contraction and could function as a human-machine interface (rather than a brain implant …) for the control of new generation prostheses.

Skin and sweat: the philosophy of this extreme innovation, that is to say, a human-machine interface in the form of a tiny patch, comes from a simple idea among its inventors: we live the world around us through our skin. From the detection of temperature, the sensation of pleasure or pain, the many nerve endings in our skin tell us a lot about the outside world. But beyond that, this team overcomes one of the main challenges of these types of portable devices, their power: “Many use batteries, but it is not very durable. Some teams have tested solar cells or the power of human movement, but we think we can get enough sweat energy to power our device, “said lead author Wei Gao of Caltech.

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Human sweat contains very high levels of lactate, a byproduct of normal metabolic processes, especially of muscles during exercise. Fuel cells integrated into the electronic skin absorb this lactate and combine it with oxygen from the atmosphere, generating water and pyruvate, another byproduct of metabolism. During their operation, biofuel batteries generate enough electricity to power the sensors and a Bluetooth device similar to that which connects a mobile to a car radio for example.

The researchers aim to develop a variety of sensors that can be integrated into the e-skin. “We want this system to be a platform, not just a portable biosensor but also a human-machine interface. Vital signs and molecular information collected using this platform could be used to optimize next generation prostheses. ”

Source: Science Robotics April 22, 2020 DOI: DOI: 10.1126 / scirobotics.aaz7946 Biofuel-powered soft electronic skin for multiplexed and wireless sensing (Visuel Caltech)

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