Graphite‑Based Sensor Boosts Sensitivity & Flexibility for Wearable Medical Devices

Researchers have developed graphene-based sensing technology using G-Putty material — a highly malleable graphene blended putty. The printed sensors are 50 times more sensitive than the industry standard and outperform other comparable nano-enabled sensors in an important metric: flexibility. Maximizing sensitivity and flexibility without reducing performance makes the technology an ideal candidate for the emerging areas of wearable electronics and medical diagnostic devices.

The team demonstrated that it can produce a low-cost, printed, graphene nanocomposite strain sensor. Creating and testing inks of different viscosities (runniness), the team found it could tailor G-Putty inks according to printing technology and application. In medical settings, strain sensors are a valuable diagnostic tool used to measure changes in mechanical strain, such as pulse rate, or changes in a stroke victim’s ability to swallow. A strain sensor works by detecting this mechanical change and converting it into a proportional electrical signal, thereby acting as mechanical-electrical converter. While strain sensors are currently available, they are mostly made from metal foil that poses limitations in terms of wearability, versatility, and sensitivity.

The team turned G-putty into an ink blend that has excellent mechanical and electrical properties. The inks can be turned into a working device using industrial printing methods, from screen printing to aerosol and mechanical deposition. An additional benefit is that the team can control a variety of different parameters during the manufacturing process, which provides the ability to tune the sensitivity of the material for specific applications calling for detection of minute strains.

The development of the sensors represents a considerable step forward in wearable diagnostic devices — devices that can be printed in custom patterns and comfortably mounted to a patient’s skin to monitor a range of different biological processes. The team is exploring applications to monitor real-time breathing and pulse, joint motion and gait, and early labor in pregnancy. Because the sensors combine high sensitivity, stability, and a large sensing range with the ability to print bespoke patterns onto flexible, wearable substrates, the team can tailor the sensor to the application.