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Abstract In recent years, wearable bioelectronics has rapidly expanded for diagnosing, monitoring, and treating various pathological conditions from the skin surface. Although the devices are typically prefabricated as soft patches for general usage, there is a growing need for devices that are customized in situ to provide accurate data and precise treatment. In this perspective, the state-of-the-art in situ fabricated wearable bioelectronics are summarized, focusing primarily on Drawn-on-Skin (DoS) bioelectronics and other in situ fabrication methods. The advantages and limitations of these technologies are evaluated and potential future directions are suggested for the widespread adoption of these technologies in everyday life. 

Abstract Accurate anatomical matching for patient-specific electromyographic (EMG) mapping is crucial yet technically challenging in various medical disciplines. The fixed electrode construction of multielectrode arrays (MEAs) makes it nearly impossible to match an individual's unique muscle anatomy. This mismatch between the MEAs and target muscles leads to missing relevant muscle activity, highly redundant data, complicated electrode placement optimization, and inaccuracies in classification algorithms. Here, we present customizable and reconfigurable drawn-on-skin (DoS) MEAs as the first demonstration of high-density EMG mapping from in situ-fabricated electrodes with tunable configurations adapted to subject-specific muscle anatomy. The DoS MEAs show uniform electrical properties and can map EMG activity with high fidelity under skin deformation-induced motion, which stems from the unique and robust skin-electrode interface. They can be used to localize innervation zones (IZs), detect motor unit propagation, and capture EMG signals with consistent quality during large muscle movements. Reconfiguring the electrode arrangement of DoS MEAs to match and extend the coverage of the forearm flexors enables localization of the muscle activity and prevents missed information such as IZs. In addition, DoS MEAs customized to the specific anatomy of subjects produce highly informative data, leading to accurate finger gesture detection and prosthetic control compared with conventional technology. 

Electrical stimulation of existing three-dimensional bioprinted tissues to alter tissue activities is typically associated with wired delivery, invasive electrode placement, and potential cell damage, minimizing its efficacy in cardiac modulation. Here, we report an optoelectronically active scaffold based on printed gelatin methacryloyl embedded with micro-solar cells, seeded with cardiomyocytes to form light-stimulable tissues. This enables untethered, noninvasive, and damage-free optoelectronic stimulation–induced modulation of cardiac beating behaviors without needing wires or genetic modifications to the tissue solely with light. Pulsed light stimulation of human cardiomyocytes showed that the optoelectronically active scaffold could increase their beating rates (>40%), maintain high cell viability under light stimulation (>96%), and negligibly affect the electrocardiogram morphology. The seeded scaffolds, termed optoelectronically active tissues, were able to successfully accelerate heart beating in vivo in rats. Our work demonstrates a viable wireless, printable, and optically controllable tissue, suggesting a transformative step in future therapy of electrically active tissues/organs. 

Untethered electrical stimulation or pacing of the heart is of critical importance in addressing the pressing needs of cardiovascular diseases in both clinical therapies and fundamental studies. Among various stimulation methods, light illumination–induced electrical stimulation via photoelectric effect without any genetic modifications to beating cells/tissues or whole heart has profound benefits. However, a critical bottleneck lies in the lack of a suitable material with tissue-like mechanical softness and deformability and sufficient optoelectronic performances toward effective stimulation. Here, we introduce an ultrathin (<500 nm), stretchy, and self-adhesive rubbery bio-optoelectronic stimulator (RBOES) in a bilayer construct of a rubbery semiconducting nanofilm and a transparent, stretchable gold nanomesh conductor. The RBOES could maintain its optoelectronic performance when it was stretched by 20%. The RBOES was validated to effectively accelerate the beating of the human induced pluripotent stem cell–derived cardiomyocytes. Furthermore, acceleration of ex vivo perfused rat hearts by optoelectronic stimulation with the self-adhered RBOES was achieved with repetitive pulsed light illumination. 

Wound healing is one of the most complex processes in the human body, supported by many cellular events that are tightly coordinated to repair the wound efficiently. Chronic wounds have potentially life-threatening consequences. Traditional wound dressings come in direct contact with wounds to help them heal and avoid further complications. However, traditional wound dressings have some limitations. These dressings do not provide real-time information on wound conditions, leading clinicians to miss the best time for adjusting treatment. Moreover, the current diagnosis of wounds is relatively subjective. Wearable electronics have become a unique platform to potentially monitor wound conditions in a continuous manner accurately and even to serve as accelerated healing vehicles. In this review, we briefly discuss the wound status with some objective parameters/biomarkers influencing wound healing, followed by the presentation of various novel wearable devices used for monitoring wounds and accelerating wound healing. We further summarize the associated device working principles. This review concludes by highlighting some major challenges in wearable devices toward wound healing that need to be addressed by the research community.