In this presentation, the concept of “discrete liquid-solid contact electrification”, which is result of sequential process of the liquid contact on the solid surface and successive detachment of contact liquid from the solid surface, is reported. After the first report on discrete liquid-solid contact electrification inside the conventional pipet tip surface, the phenomenon is deeply investigated and explored with the help of utilization on a hydrophobic surfaces, which enables easy detachment of liquid from its surface. As a result, the phenomenon can be intentionally suppressed and/or enhanced.

Recently, discrete liquid-solid contact electrification has been utilized as a fundamental operation mechanism of the self-powered sensor, which utilizes the contact electrification phenomenon with electrical induction to efficiently convert ambient mechanical energy to electrical energy. In this paper, the fabrication of the self-powered sensor utilizing discrete liquid-solid contact electrification is introduced to help its understanding.

With the fact that ordinary pipetting procedure always involves spontaneous discrete liquid-solid contact electrification resulting in generation of net electrical charges on the inner surface of the polymeric pipet tip, in this study, a concept of a smart pipet tip is newly proposed to evaluate the electrolyte concentration of the dispensed solution. The smart pipet tip possessing triboelectricity and thermoelectricity detecting modules is advantageous as it performs in situ evaluation of solution characteristics without any subsidiary solution handling process. The spontaneously generated electric signals are intensively investigated with the theoretical analyses. The proof-of-concept demonstration of the present smart pipet tip is shown for in situ prediction of morphology of nanoparticles during their synthetic reaction, which critically determines their catalytic activity. The present study would broaden the applications of discrete liquid-solid contact electrification, which is ubiquitous but previously inconspicuous in our daily life.