What does a sliding triboelectrical sensor really measure ?

For a decade, Triboelectric Nanogenerators (TENG) have beenmassively developed and optimized either as (i) triboelectricenergy harvesters or, (ii) triboelectric self-powered sensors.Unfortunately, it is obvious that the classical tribologists’concerns – like the optimization of both real contact area,friction laws and wear processes – have never really beenintegrated so far neither in their development processes nor intheir triboelectrical responses. Thus, a question as basic as “Whatkind of tribological information can we expect from multi-asperitytriboelectric sensor rubbing on a plane in dry friction?” doescurrently not lead to a trivial answer. This paper tries to get outthis paradoxical situation by simulating triboelectrical behaviorof a multi-asperity real contact area in dry friction. Resultsreveal that a sliding triboelectric sensor assesses theinstantaneous and averaged velocities of every interactingasperities within the contact area, finally probing, in real time,the tribological actual contact area behavior during sliding.