Peripheral nerves are often vulnerable to damage during surgeries, with risks of significant pain, loss of motor function, and reduced quality of life for the patient. Intraoperative methods for monitoring nerve activity are effective, but conventional systems rely on bench-top data acquisition tools with hard-wired connections to electrode leads that must be placed percutaneously inside target muscle tissue. These approaches are time and skill intensive and therefore costly to an extent that precludes their use in many important scenarios. Here we report a soft, skin-mounted monitoring system that measures, stores, and wirelessly transmits electrical signals and physical movement associated with muscle activity, continuously and in real-time during neurosurgical procedures on the peripheral, spinal, and cranial nerves. Surface electromyography and motion measurements can be performed non-invasively in this manner on nearly any muscle location, thereby offering many important advantages in usability and cost, with signal fidelity that matches that of the current clinical standard of care for decision making. These results could significantly improve accessibility of intraoperative monitoring across a broad range of neurosurgical procedures, with associated enhancements in patient outcomes.

Wearable sensors have the potential to enable clinical-grade ambulatory health monitoring outside the clinic. Technological advances have enabled development of devices that can measure vital signs with great precision and significant progress has been made towards extracting clinically meaningful information from these devices in research studies. However, translating measurement accuracies achieved in the controlled settings such as the lab and clinic to unconstrained environments such as the home remains a challenge. In this paper, we present a novel wearable computing platform for unobtrusive collection of labeled datasets and a new paradigm for continuous development, deployment and evaluation of machine learning models to ensure robust model performance as we transition from the lab to home. Using this system, we train activity classification models across two studies and track changes in model performance as we go from constrained to unconstrained settings.

Wearable sensors have the potential to enable longitudinal, objective health monitoring in patients with chronic diseases, including cardiac rhythm disorders, neurological and movement disorders, diabetes, and pain. However, conventional wearable devices are typically comprised of rigid, packaged electronics, which may compromise overall signal fidelity and wearer comfort during activities of daily living and sleep. In this chapter, we present recent advances in the development of thin and stretchable epidermal systems for biometric data measurements. These non-invasive epidermal systems are fully integrated with multiple sensors, an analog front end module, a radio for wireless communicationBluetooth low energy (BTLE) radio , onboard flash memory, a rechargeable battery all encapsulated in a soft, stretchable and water-resistant silicone, and with an air permeable adhesive layer that interfaces with the human skin. The encapsulated system intimately couples with the skin at multiple locations on the body. We present results showing the potential of this technology to quantitatively assess bio-kinematics and electrophysiological signals. Finally, we provide perspectives on remaining challenges and opportunities to achieve clinical validation and commercial adoption of these technologies.

Human skin-like core/shell material encapsulating structures for wearable electronics serve to minimize interface stresses and mechanical constraints on natural body motions, with ability to strain isolate the active devices. On page 3698, Y. Huang, J. A. Rogers, and co-workers show how integrating emerging commercial classes of stretchable electronics into this type of structure provides systems with capabilities in continuous, precision wireless monitoring of motion and skin temperatures during exercise.

This paper presents materials and core/shell architectures that provide optimized mechanical properties in packages for stretchable electronic systems. Detailed experimental and theoretical studies quantitatively connect the geometries and elastic properties of the constituent materials to the overall mechanical responses of the integrated systems, with a focus on interfacial stresses, effective modulus, and maximum extent of elongation. Specific results include core/shell designs that lead to peak values of the shear and normal stresses on the skin that remain less than 10 kPa even for applied strains of up to 20%, thereby inducing minimal somatosensory perception of the device on the human skin. Additional, strain‐limiting mesh structures embedded in the shell improve mechanical robustness by protecting the active components from strains that would otherwise exceed the fracture point. Demonstrations in precommercial stretchable electronic systems illustrate the utility of these concepts.

In this paper, we present a stretchable wearable system capable of i) measuring multiple physiological parameters and ii) transmitting data via radio frequency to a smart phone. The electrical architecture consists of ultra thin sensors (<; 20 μm thick) and a conformal network of associated active and passive electronics in a mesh-like geometry that can mechanically couple with the curvilinear surfaces of the human body. Spring-like metal interconnects between individual chips on board the device allow the system to accommodate strains approaching ~30% A representative example of a smart patch that measures movement and electromyography (EMG) signals highlights the utility of this new class of medical skin-mounted system in monitoring a broad range of neuromuscular and cardiovascular diseases.