Monitoring of finger manipulation without disturbing the inherent functionalities is critical to understand the sense of natural touch. However, worn or attached sensors affect the natural feeling of the skin. We developed nanomesh pressure sensors that can monitor finger pressure without detectable effects on human sensation. The effect of the sensor on human sensation was quantitatively investigated, and the sensor-applied finger exhibits comparable grip forces with those of the bare finger, even though the attachment of a 2-micrometer-thick polymeric film results in a 14% increase in the grip force after adjusting for friction. Simultaneously, the sensor exhibits an extreme mechanical durability against cyclic shearing and friction greater than hundreds of kilopascals.

Aging, neurologic diseases, and diabetes are a few risk factors that may lead to underactive bladder (UAB) syndrome. Despite all of the serious consequences of UAB, current solutions, the most common being ureteric catheterization, are all accompanied by serious shortcomings. The necessity of multiple catheterizations per day for a physically able patient not only reduces the quality of life with constant discomfort and pain but also can end up causing serious complications. Here, we present a bistable actuator to empty the bladder by incorporating shape memory alloy components integrated on flexible polyvinyl chloride sheets. The introduction of two compression and restoration phases for the actuator allows for repeated actuation for a more complete voiding of the bladder. The proposed actuator exhibits one of the highest reported voiding percentages of up to 78% of the bladder volume in an anesthetized rat after only 20 s of actuation. This amount of voiding is comparable to the common catheterization method, and its one time implantation onto the bladder rectifies the drawbacks of multiple catheterizations per day. Furthermore, the scaling of the device for animal models larger than rats can be easily achieved by adjusting the number of nitinol springs. For neurogenic UAB patients with degraded nerve function as well as degenerated detrusor muscle, we integrate a flexible triboelectric nanogenerator sensor with the actuator to detect the fullness of the bladder. The sensitivity of this sensor to the filling status of the bladder shows its capability for defining a self-control system in the future that would allow autonomous micturition.

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Abstract-This paper presents the design, modeling, and optimization of an electromagnetic energy harvesting (EMEH) device with various tube length and winding coil width. The nonlinear magnetic-spring configuration is employed for generating sufficient power from hand shaking of irregular and low-frequency vibrations. Based on the modeling and simulation, longer tube length of the EMEH device results in lower resonant frequency and stronger nonlinearity of the system and thus is more efficient for low-frequency harvesting. From the hand shaking test, it is found that a longer tube length and a shorter winding coil width could induce a higher power generation. The optimized device of tube length of 66 mm and winding coil width of 10 mm has achieved maximum power outputs of 568.66 µW at the hand shaking acceleration of 1 g and frequency of 6.7 Hz, which corresponds to the power density of 90.67 µW/cm 3 . Further improvement of the device has been achieved by increasing the coil length to 40 m. This device provides maximum power outputs of 825.36 µW at the hand shaking acceleration of 1.56 g and frequency of 6.7 Hz. This paper demonstrates a feasible design of nonlinear EMEH device with impressive output performance from hand shaking.Index Terms-Electromagnetic energy harvester (EMEH), nonlinear, magnetic-spring, hand shaking.