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Tissue-on-chip systems represent promising platforms for monitoring and controlling tissue functions in vitro for various purposes in biomedical research. The two-dimensional (2D) layouts of these constructs constrain the types of interactions that can be studied and limit their relevance to three-dimensional (3D) tissues. The development of 3D electronic scaffolds and microphysiological devices with geometries and functions tailored to realistic 3D tissues has the potential to create important possibilities in advanced sensing and control. This study presents classes of compliant 3D frameworks that incorporate microscale strain sensors for high-sensitivity measurements of contractile forces of engineered optogenetic muscle tissue rings, supported by quantitative simulations. Compared with traditional approaches based on optical microscopy, these 3D mechanical frameworks and sensing systems can measure not only motions but also contractile forces with high accuracy and high temporal resolution. Results of active tension force measurements of engineered muscle rings under different stimulation conditions in long-term monitoring settings for over 5 wk and in response to various chemical and drug doses demonstrate the utility of such platforms in sensing and modulation of muscle and other tissues. Possibilities for applications range from drug screening and disease modeling to biohybrid robotic engineering.

Phototherapy represents an attractive route for treating a range of challenging dermatological diseases. Existing skin phototherapy modalities rely on direct UV illumination, although with limited efficacy in addressing disorders of deeper tissue and with requirements for specialized illumination equipment and masks to shield unaffected regions of the skin. This work introduces a skin‐integrated optoelectronic device that incorporates an array of UVA (360 nm) light emitting diodes in layouts that match those of typical lesional plaques and in designs that couple to biocompatible, penetrating polymer microneedle light waveguides to provide optical access to deep skin. Monte Carlo simulations and experimental results in phantom skin suggest that these waveguides significantly enhance light delivery to deep skin, with a >4‐fold increase for depths of >500 µm. In ex vivo human skin, the devices show reduced measures of phototoxicity compared to direct illumination and enhanced modulation of gene expression relevant to sclerosing skin diseases. These systems are also compatible with design principles in soft, skin‐compatible electronics and battery‐powered wireless operation. Collectively, the favorable mechanical and light delivery properties of these devices expand possibilities in targeting of deep skin lesions beyond those attainable with clinical‐standard UV light therapy approaches.