Quick evaluation and regulation of the maximum instantaneous power and matching resistance for droplet-based electricity generators

Droplet-based electricity generators (DEGs) leveraging triboelectric effects are simple and high-performance devices for harvesting energy from ubiquitous water droplets. Instantaneous power plays a vital role in wide applications of DEGs. However, the governing law of the maximum instantaneous power and matching resistance is lacking and their determination suffers from heavy repetitive experiments, hindering the development of DEGs. Herein, we propose a quick evaluation method for the internal droplet impedance, instantaneous peak power, maximum instantaneous power and matching resistance which exhibits broad universality and excellent accuracy. Moreover, effects of diverse factors pertaining to droplets and devices are fully investigated, highlighting that the maximum instantaneous power and matching resistance can be effectively regulated across multiple orders of magnitudes by controlling the salt concentration. Our findings shed insights into the understanding, evaluation, and regulation of instantaneous power for DEGs, and shall promote the renovation of the DEG technology.

PARAMETRIC MATCHING SELECTION OF MULTI-MEDIUM COUPLING SHOCK ABSORBER

To achieve the dual demand of resisting violent impact and attenuating vibration in vibration-impact-safety of protection for precision equipment such as MEMS packaging system, a theo- retical mathematical model of multi-medium coupling shock absorber is presented. The coupling of quadratic damping, linear damping, Coulomb damping and nonlinear spring are considered in the model. The approximate theoretical calculating formulae are deduced by introducing transformation-tactics. The contrasts between the analytical results and numerical integration results are developed. The resisting impact characteristics of the model are also analyzed in progress. In the meantime, the optimum model of the parameters matching selection for design of the shock absorber is built. The example design is illustrated to confirm the validity of the modeling method and the theoretical solution.

A 0.1–1.5 GHz multi-octave quadruple-stacked CMOS power amplifier

In this letter,we design and analyze 0.1–1.5 GHz multi-octave quadruple-stacked CMOS power amplifier(PA)in 0.18μm CMOS technology.By using two-stage quadruple-stacked topology and feedback technology,the proposed PA realizes an ultra-wideband CMOS PA in a small chip area.Wideband impedance matching is achieved with smaller chip dimension.The effects of feedback resistors on the RF performance are also discussed for this stacked-FET PA.The PA shows measured input return loss(<–10.8 dB)and output return loss(<–9.6 dB)in the entire bandwidth.A saturated output power of 22 dBm with maximum 20%power added efficiency(PAE)is also measured with the drain voltage at 5 V.The chip size is 0.44 mm^2 including all pads.