Highly stretchable, flexible, and sensitive strain sensors have promising applications in motion detection—especially multifunctional strain sensors that can detect stretching, bending, compression and twisting. Herein, this study presents a graphene and glycerol solution-based multifunctional sensor with ultra-high stretchability and sensitivity. Owing to the self-lubrication and fluidity of the graphene-glycerol solution, the strain sensors display super stretchability up to 1000%, a maximum gauge factor up to 45.13, and excellent durability for over 10,000 cycles. In addition, the sensor can also rapidly respond to small strains (1%, 5%, 10%) and different stretching rates (12.5%/s, 25%/s, 50%/s, and 100%/s). More impressively, the sensors can measure up to 50 kPa pressure and 180° twisting without any damage. Furthermore, the strain sensors demonstrate their applicability in scenarios involving motion detection, such as that for finger bending, wrist rotating, touching, and drinking water.
The process of localized electrochemical deposition (LECD) offers the potential to fabricate complex structures using the layer-bylayer movement of an anode or a cathode, similar to 3D printing. This work demonstrates the fabrication of micro sized copper walls using the LECD process, which is critical for MEMS and semiconductor-related applications. First, copper walls with different morphologies were deposited by moving the micro anode layer by layer and controlling the applied voltage between the electrodes during LECD. Next, the effect of the deposition voltage and anode trajectory (layer height and step length) on the profile of copper walls and the roughness of the wall surface were studied. It was found that the deposition voltage and layer height significantly influenced the profiles and deposition rates. Under applied voltage in the range 2.8-3.0 V and with a layer height of 2 μm, copper walls with a completely densified surface can be obtained. Finally, three copper wall growth patterns, namely, parallel column growth, spaced column growth and bifurcated column growth, were proposed to describe the wall growth mechanism.
This paper studies the effects of applied potential on the LECD process. which are critical for microelectromechanical systems and semiconductor-related applications. The structures and morphologies of the copper columns can be varied by changing the voltage between the anode and cathode, and high voltage leads to complex structures and morphology. Additionally, the cross section of copper columns was investigated to evaluate the quality of internal structure of columns, and the voids were appeared and the shape of cross section became irregular with the increase of voltage. Finally, the basement of columns was studied for the first time, and three kinds of column basements, i.e., isolated, disordered, and delicate, were identified, and three growth patterns corresponding to the three typical basements types were proposed to describe the basement growth mechanism.
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