Owing to its high carrier mobility, conductivity, flexibility and optical transparency, graphene is a versatile material in micro- and macroelectronics. However, the low density of electrochemically active defects in graphene synthesized by chemical vapour deposition limits its application in biosensing. Here, we show that graphene doped with gold and combined with a gold mesh has improved electrochemical activity over bare graphene, sufficient to form a wearable patch for sweat-based diabetes monitoring and feedback therapy. The stretchable device features a serpentine bilayer of gold mesh and gold-doped graphene that forms an efficient electrochemical interface for the stable transfer of electrical signals. The patch consists of a heater, temperature, humidity, glucose and pH sensors and polymeric microneedles that can be thermally activated to deliver drugs transcutaneously. We show that the patch can be thermally actuated to deliver Metformin and reduce blood glucose levels in diabetic mice.

Thermal therapy is one of the most popular physiotherapies and it is particularly useful for treating joint injuries. Conventional devices adapted for thermal therapy including heat packs and wraps have often caused discomfort to their wearers because of their rigidity and heavy weight. In our study, we developed a soft, thin, and stretchable heater by using a nanocomposite of silver nanowires and a thermoplastic elastomer. A ligand exchange reaction enabled the formation of a highly conductive and homogeneous nanocomposite. By patterning the nanocomposite with serpentine-mesh structures, conformal lamination of devices on curvilinear joints and effective heat transfer even during motion were achieved. The combination of homogeneous conductive elastomer, stretchable design, and a custom-designed electronic band created a novel wearable system for long-term, continuous articular thermotherapy.

375wileyonlinelibrary.com the human body and bulky devices [3][4][5] ; the unnatural appearance owing to the infl exibility of electronics [ 6 ] ; and the signal artifacts that originate from the non-conformal attachment of the rigid sensors to the human body. [3][4][5] Therefore, novel ultrathin devices that can be conformally laminated onto human skin such that they have natural appearance, comfort, and high signal-to-noise ratio (SNR) are desired.The adoption of fl exible and stretchable designs and a concomitant reduction in the thickness and weight of devices are key goals with respect to the design of wearable electronics. Signifi cant efforts have been made recently, including the development of stretchable inorganic electronics, [ 3,4,7 ] ultrathin and lightweight organic sensors, [ 8,9 ] fl exible nanomaterialbased electronic skins, [ 10,11 ] self-powered motion sensors based on the triboelectric effect, [ 12,13 ] and highly sensitive fl exible mechanical sensors. [14][15][16][17] Ultrathin and deformable designs allow for accurate data acquisition from the human body with minimum signal artifacts. However, these previously reported devices are made of opaque semiconductors and metals, which look different from human skin. In addition, many of these sensors lack power supply devices [3][4][5] and thus self-powering is important.Transparent electronic nanomaterials can make wearable devices invisible, resulting in a natural look and improved aesthetics. For example, carbon-based nanomaterials (such as graphene (GP) [ 18 ] and carbon nanotubes [ 19 ] and metal nanowire (NW) networks (such as silver NWs [ 20 ] and gold NWs [ 21 ] have been intensively researched. These transparent nanomaterials An interactive human-machine interface (iHMI) enables humans to control hardware and collect feedback information. In particular, wearable iHMI systems have attracted tremendous attention owing to their potential for use in personal mobile electronics and the Internet of Things. Although significant progress has been made in the development of iHMI systems, those based on rigid electronics have constraints in terms of wearability, comfortability, signal-to-noise ratio (SNR), and aesthetics. Herein the fabrication of a transparent and stretchable iHMI system composed of wearable mechanical sensors and stimulators is reported. The ultrathin and lightweight design of the system allows superior wearability and high SNR. The use of conductive/piezoelectric graphene heterostructures, which consist of poly( L -lactic acid), single-walled carbon nanotubes, and silver nanowires, results in high transparency, excellent performance, and low power consumption as well as mechanical deformability. The control of a robot arm for various motions and the feedback stimulation upon successful executions of commands are demonstrated using the wearable iHMI system.