Battery-free, wireless sensors for full-body pressure and temperature mapping

Pressure ulcers, or bedsores, can develop at skin sites overlying bony areas of the body when a patient remains in one position for an extended period. These sores can be difficult to detect in their early stages. To begin to address this, Han et al . developed flexible, adherent sensors that measure skin temperature and pressure in real time. The small sensors use wireless power to communicate with external reader antennas. Data acquired from multiple sensors were used to create full-body pressure and temperature maps, which detected changes in pressure due to adjusting the angle of hospital bed incline and changes in skin temperature during sleep in human participants during proof-of-concept studies. Thin, soft, skin-like sensors capable of precise, continuous measurements of physiological health have broad potential relevance to clinical health care. Use of sensors distributed over a wide area for full-body, spatiotemporal mapping of physiological processes would be a considerable advance for this field. We introduce materials, device designs, wireless power delivery and communication strategies, and overall system architectures for skin-like, battery-free sensors of temperature and pressure that can be used across the entire body. Combined experimental and theoretical investigations of the sensor operation and the modes for wireless addressing define the key features of these systems. Studies with human subjects in clinical sleep laboratories and in adjustable hospital beds demonstrate functionality of the sensors, with potential implications for monitoring of circadian cycles and mitigating risks for pressure-induced skin ulcers.