Force-induced charge carrier storage: a new route for stress recording

Yixi Zhuang,Guorong Chen,Le Wang,Hongwu Zhang,Rong-Jun Xie,Lizong Dai,Hao Xue,Changjian Chen,Caofeng Pan,Dong Tu,Conghui Yuan

doi:10.1038/s41377-020-00422-4

Abstract

Stress sensing is the basis of human-machine interface, biomedical engineering, and mechanical structure detection systems. Stress sensing based on mechanoluminescence (ML) shows significant advantages of distributed detection and remote response to mechanical stimuli and is thus expected to be a key technology of next-generation tactile sensors and stress recorders. However, the instantaneous photon emission in ML materials generally requires real-time recording with a photodetector, thus limiting their application fields to real-time stress sensing. In this paper, we report a force-induced charge carrier storage (FICS) effect in deep-trap ML materials, which enables storage of the applied mechanical energy in deep traps and then release of the stored energy as photon emission under thermal stimulation. The FICS effect was confirmed in five ML materials with piezoelectric structures, efficient emission centres and deep trap distributions, and its mechanism was investigated through detailed spectroscopic characterizations. Furthermore, we demonstrated three applications of the FICS effect in electronic signature recording, falling point monitoring and vehicle collision recording, which exhibited outstanding advantages of distributed recording, long-term storage, and no need for a continuous power supply. The FICS effect reported in this paper provides not only a breakthrough for ML materials in the field of stress recording but also a new idea for developing mechanical energy storage and conversion systems.

Highlights

Mechanoluminescence (ML) materials featuring photon emission under mechanical stimuli have attracted the attention of material scientists, physicists and engineers[1,2,3,4,5,6] due to their promising applications in structure damage diagnosis platforms, E-signature systems, artificial skins and optical anti-counterfeiting devices[7,8,9,10,11,12]
force-induced charge carrier storage (FICS) effect in SrSi2O2N2:Eu2+,Dy3+ In a typical measurement procedure, phosphor samples were heat-treated at 600 K, ground in the dark by using an agate rod at room temperature (RT) (ii), and heated again for thermoluminescence (TL) tests (iii)
Based on the above experimental results, we preliminarily proved that the FICS effect exists in the SrSi2O2N2:Eu2+,Dy3+ phosphor, i.e., the charge carriers can be excited by a mechanical stimulus and captured and stored in the deep traps of the ML materials

Summary

Introduction

Mechanoluminescence (ML) materials featuring photon emission under mechanical stimuli have attracted the attention of material scientists, physicists and engineers[1,2,3,4,5,6] due to their promising applications in structure damage diagnosis platforms, E-signature systems, artificial skins and optical anti-counterfeiting devices[7,8,9,10,11,12]. Charge carriers are pumped into shallow traps by light pre-excitation[22,23,24,25] or force loading[26,27,28,29,30] (Fig. 1a:i). The charge carriers are released from shallow traps at an accelerated rate under force loading, leading to instantaneous photon emission. The accelerated release of charge carriers is related to trap depth reduction. In this regard, an energy model of band titling

Methods

Results

Conclusion