Electronically-enabled wearable systems that monitor physiological activity and electrophysiological activity hold the key to truly personalized medical care outside of the hospital setting. However, fundamental technical challenges exist in achieving medical systems that are comfortable, unobtrusive and fully integrated without external connections to bench top instruments. In particular, there is a fundamental mismatch in mechanical coupling between existing classes of rigid electronics and soft biological substrates, like the skin. Here we describe new mechanical and electrical design strategies for wearable devices with mechanical properties that approach that of biological tissue. These systems exploit stretchable networks of conformal sensors (i.e. electrodes, temperature sensors, and accelerometers) and associated circuitry (i.e. microcontroller, memory, voltage regulators, rechargeable battery, wireless communication modules) embedded in ultrathin, elastomeric substrates. Quantitative analyses of sensor performance and mechanics under tensile and torsional stresses illustrate the ability to mechanically couple with soft tissues in a way that is mechanically invisible to the user. Representative examples of these soft biointegrated systems can be applied for continuous sensing of muscle and movement activity in the home and ambulatory settings.
Current technology development in light emitting diodes has enabled high efficiency operation, low energy
consumption and lifetimes, thereby creating new possibilities in conventional display and lighting industry. Recent
work is also creating more unusual uses in biomedicine and in sensing applications, where conformal contact over
curvilinear surfaces is required. Here, ultrathin device geometries and optimized mechanical designs, including
neutral mechanical plane layouts and serpentine interconnects, provide indicators and lighting modules with
arbitrary shapes capable of integrated on nearly any type of substrates. Biomedical devices such as light emitting suture threads, and glove-mounted optical proximity sensors demonstrate the versatility of this strategy and create
great new opportunities.