Wearable systems that monitor muscle activity, store data and deliver feedback therapy are the next frontier in personalized medicine and healthcare. However, technical challenges, such as the fabrication of high-performance, energy-efficient sensors and memory modules that are in intimate mechanical contact with soft tissues, in conjunction with controlled delivery of therapeutic agents, limit the wide-scale adoption of such systems. Here, we describe materials, mechanics and designs for multifunctional, wearable-on-the-skin systems that address these challenges via monolithic integration of nanomembranes fabricated with a top-down approach, nanoparticles assembled by bottom-up methods, and stretchable electronics on a tissue-like polymeric substrate. Representative examples of such systems include physiological sensors, non-volatile memory and drug-release actuators. Quantitative analyses of the electronics, mechanics, heat-transfer and drug-diffusion characteristics validate the operation of individual components, thereby enabling system-level multifunctionalities.

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Implantable endovascular devices such as bare metal, drug eluting, and bioresorbable stents have transformed interventional care by providing continuous structural and mechanical support to many peripheral, neural, and coronary arteries affected by blockage. Although effective in achieving immediate restoration of blood flow, the long-term re-endothelialization and inflammation induced by mechanical stents are difficult to diagnose or treat. Here we present nanomaterial designs and integration strategies for the bioresorbable electronic stent with drug-infused functionalized nanoparticles to enable flow sensing, temperature monitoring, data storage, wireless power/data transmission, inflammation suppression, localized drug delivery, and hyperthermia therapy. In vivo and ex vivo animal experiments as well as in vitro cell studies demonstrate the previously unrecognized potential for bioresorbable electronic implants coupled with bioinert therapeutic nanoparticles in the endovascular system.

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Implantation of biodegradable wafers near the brain surgery site to deliver anti-cancer agents which target residual tumor cells by bypassing the blood-brain barrier has been a promising method for brain tumor treatment. However, further improvement in the prognosis is still necessary. We herein present novel materials and device technologies for drug delivery to brain tumors, i.e., a flexible, sticky, and biodegradable drug-loaded patch integrated with wireless electronics for controlled intracranial drug delivery through mild-thermic actuation. The flexible and bifacially-designed sticky/hydrophobic device allows conformal adhesion on the brain surgery site and provides spatially-controlled and temporarily-extended drug delivery to brain tumors while minimizing unintended drug leakage to the cerebrospinal fluid. Biodegradation of the entire device minimizes potential neurological side-effects. Application of the device to the mouse model confirms tumor volume suppression and improved survival rate. Demonstration in a large animal model (canine model) exhibited its potential for human application.

telemedicine, mobile health, prosthetics, athletic training, human-machine interface (HMI) and so on. From "skin-like" electronics (a.k.a. e-skins) [1] to "epidermal electronics" (a.k.a. e-tattoos), [2] people are hopeful that the emerging flexible/ stretchable electronics technologies will disrupt the wearable industry. Specifically, e-tattoos are ultrathin, ultrasoft membranes that can well conform to the skin to monitor a variety of biomarkers including electrophysiology, [3] mechanoacoustic signals, [4] skin temperature, [5] skin hydration, [6] skin stiffness, [7] blood pressure, [8] blood oxygen saturation, [9] and even sweat analytes. [10] Wireless communication enabled by near field communication (NFC) [9a,11] and Bluetooth [12] have also been demonstrated in a few recent e-tattoos. However, which biomarker to measure is highly personal and may vary from time to time for the same individual. Moreover, different biomarkers should be measured at different locations using different types of sensors and read-out circuits. Even if one can build a multimodal e-tattoo, excessive recordings not personalized to the user may cause unnecessary power and bandwidth consumption, which is a major concern for wireless wearables. Although it is possible to build specific e-tattoos for specific sensing tasks, it would be a big waste of the wireless transmission and read-out circuits if the whole e-tattoo has to be disposed after just one use.Herein, we propose a possible remedy for all the aforementioned challenges-the modular and reconfigurable e-tattoos, where layers of distinct functionalities (e.g., NFC layer, analog front end (AFE) layer, electrode layer, etc.) can be pre-fabricated as building blocks that can be picked and assembled into customized e-tattoos and can also be swapped out to form new e-tattoos. Electrical connections between the layers can be achieved through aligned vias. Compared with existing monolayer, fully pre-defined e-tattoos, the newly proposed modular and reconfigurable e-tattoos would have the following appealing advantages. First, the multilayer stack can effectively shrink the footprint of the e-tattoo on the skin, especially when numerous components and complex circuits are needed for signal read-out and wireless transmission. Second, when the measurement is done, only the passive electrode/sensor layer that has been in direct contact with the skin needs to be peeled off from the e-tattoo and disposed. As a result, the leftover NFC In the past few years, ultrathin and ultrasoft epidermal electronics (a.k.a. e-tattoos) emerged as the next-generation wearables for telemedicine, mobile health, performance tracking, human-machine interface (HMI), and so on. However, it is not possible to build an all-purpose e-tattoo that can accommodate such a wide range of applications. Thus, the design, fabrication, and validation of modular and reconfigurable wireless e-tattoos for personalized sensing are reported. Such e-tattoos feature a multilayer stack of stretchable layers of distinct function...

Mechanically stretchable photonics provides a new geometric degree of freedom for photonic system design and foresees applications ranging from artificial skins to soft wearable electronics. Here we describe the design and experimental realization of the first single-mode stretchable photonic devices. These devices, made of chalcogenide glass and epoxy polymer materials, are monolithically integrated on elastomer substrates. To impart mechanical stretching capability to devices built using these intrinsically brittle materials, our design strategy involves local substrate stiffening to minimize shape deformation of critical photonic components, and interconnecting optical waveguides assuming a meandering Euler spiral geometry to mitigate radiative optical loss. Devices fabricated following such design can sustain 41% nominal tensile strain and 3000 stretching cycles without measurable degradation in optical performance. In addition, we present a rigorous analytical model to quantitatively predict stress-optical coupling behavior in waveguide devices of arbitrary geometry without using a single fitting parameter.

While several functional platforms for cell culturing have been proposed for cell sheet engineering, a soft integrated system enabling in vitro physiological monitoring of aligned cells prior to their in vivo applications in tissue regeneration has not been reported. Here, we present a multifunctional, soft cell-culture platform equipped with ultrathin stretchable nanomembrane sensors and graphene-nanoribbon cell aligners, whose system modulus is matched with target tissues. This multifunctional platform is capable of aligning plated cells and in situ monitoring of cellular physiological characteristics during proliferation and differentiation. In addition, it is successfully applied as an in vitro muscle-on-a-chip testing platform. Finally, a simple but high-yield transfer printing mechanism is proposed to deliver cell sheets for scaffold-free, localized cell therapy in vivo. The muscle-mimicking stiffness of the platform allows the high-yield transfer printing of multiple cell sheets and results in successful therapies in diseased animal models. Expansion of current results to stem cells will provide unique opportunities for emerging classes of tissue engineering and cell therapy technologies.