Stretchable electronic circuits conform to irregular three dimensional surfaces. They are formed with soft materials and contain electronic circuits, sensors, and other components. We report on a soft matter based rechargeable electrochemical power storage element for such devices. The chemistry is based on a rechargeable alkaline manganese battery concept. The cells withstand more than 700 mechanical stretch relaxation cycles up to 25% strain, with an average cell capacity of 6.5 mA h. Combined with wireless power transmission or stretchable solar cells, the rechargeable battery can be used to store and supply energy in stretchable electronic devices.
Toy bricks are an ideal platform for the cost‐effective rapid prototyping of a tabletop tensile tester with measurement accuracy on par with expensive, commercially available laboratory equipment. Here, a tester is presented that is not only a versatile demonstration device in mechanics, electronics, and physics education and an eye‐catcher on exhibitions, but also a powerful tool for stretchable electronics research. Following the “open‐source movement” the build‐up of the tester is described and all the details for easy reproduction are disclosed. A a new design of highly conformable all‐elastomer based graded rigid island printed circuit boards is developed. Tough bonded to this elastomer substrate are imperceptible electronic foils bearing conductors and off‐the‐shelf microelectronics, paving the way for next generation smart electronic appliances.
Metal oxide thin films for soft and flexible electronics require low cost, room temperature fabrication, and structuring processes. We here introduce an anodic printing process to realize the essential building blocks of electronic circuitry, including resistors, capacitors, field-effect transistors, diodes, rectifiers, and memristors directly on imperceptible plastic substrates. Largely independent on surface properties, we achieve high-quality, few nanometer thin dielectric and semiconducting films even on rough substrates via localized anodisation of valve metals using a scanning droplet cell microscope. We demonstrate printing-like fabrication of 3D multilayer solid-state capacitors with a record-high areal capacity of 4 µF cm −2 . Applicable to the whole class of valve metals and their alloys, our method provides a versatile fabrication technique for the circuits that empower the flexible and stretchable electronics of tomorrow.
Wearable healthcare devices monitor the condition of patients outside the hospital and hence increase treatment capacity and resources. At the same time, patients benefit from wireless data transmission and conformable device designs, speeding up the rehabilitation process and integration into normal daily activities. Yet, the successful implementation of personalized treatment creates an extensive engineering challenge as devices need to adapt to a vast number of different patients and treatment protocols. Herein, soft building blocks of mobile health (mHealth) devices that reversibly assemble through a magnetic click‐on mechanism are introduced. Fabrication of reliable magnetic connectors with an inherent safeguard mechanism allows the realization of personalized wearable mHealth devices, independent of the (desired) measurement technique. Stretchable elastomer‐based units combined with imperceptible electrodes are protected from overstretching by controlling the opening force of the magnetic connections. The stretchable devices retain both electrical and mechanical functionality for more than 10 000 opening cycles, on par with the standard for universal serial bus type C (USB C) connectors used in consumer electronics. A fully functional and autonomous pulse sensor wristband, assembled from the reliably connecting circuits, demonstrates the feasible implementation for mHealth devices. The plug‐and‐play modularity ensures the applicability independent of a patient's needs, without sacrificing functionality and durability.
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