The current prototype serves as a self-powered radial artery pulse monitor, but other aspects of health – such as heart rate, body temperature or blood pressure – can be gauged by simply changing the sensor circuitry. (Credit: UCI)

A new self-powered, wristwatch-style health monitor can keep track of a wearer’s pulse and wirelessly communicate with a nearby smartphone or tablet — without needing an external power source or a battery.

The wearable was built via 3D printing of nanomaterials on flexible substrates for real-time and wireless monitoring of vital signs. The current prototype serves as a self-powered radial artery pulse monitor, but other aspects of health — such as heart rate, body temperature, or blood pressure — can be gauged by simply changing the sensor circuitry.

The device delivers health information in two ways. In one mode, the energy created by tapping the wristband’s nano energy generators powers up the sensor circuitry, and soon the wearer’s pulse rate appears as flashing signals on an LED display. The second mode works when a smartphone or similar device is held near the wearable. Embedded near-field communication technology facilitates the wireless exchange of both power and data between the wristband and the mobile device, and biophysical information is plotted and displayed on the smartphone’s screen.

The on-demand and self-powered characteristics of the invention are made possible by triboelectric nanogenerators that produce voltage through mechanical thumping or pressure. The TENGs are fabricated using titanium-based MXenes, a relatively new class of ultrathin 2D material with unique electrical and mechanical properties. Only a few atoms thick, MXene layers are bendable, are stretchable and can be printed onto the surface of flexible, bandage-like material or a wearable arm- or wristband.

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