Strain-sensitive mechanoluminescence with high stability and self-recovery toward stretchable strain sensor

Due to its unique strain-light response, non-contact measurement and visualization characteristics, strain-sensitive mechanoluminescent (ML) materials are expected to replace traditional strain gauges as a new generation of strain sensing materials. The strain sensing technology has high requirements for the multi-parameter response characteristics, stability and sensing working range of sensing materials. In this work, a composite flexible strain sensing ML device composed of La4GeO8 doped with lanthanide rare earth ions Ln3+ and polydimethylsiloxane (PDMS) is proposed. The ML of the device can produce good linear response to stress, strain and loading rate under tensile action. The minimum strain response threshold is less than 2% of the relative strain, and the sensing range can reach 100% of the relative strain in the full elastic deformation range. In addition, the ML intensity of La4GeO8: Ln3+@PDMS has the characteristic of self-recovery, and its self-recovery is related to the maximum strain of loading and the placing time. The wavelength (visible-near infrared) and color adjustable ML can be achieved by adjusting the type and doping concentration of rare earth ions. Moreover, the device has high thermal stability and water resistance, indicating that it is also adaptable to extremely harsh environments. The results show that La4GeO8: Ln3+@PDMS can be used as a strain-sensing-material with multi-dimensional mechanical parameter response, and has potential application prospects in the field of flexible tensile strain sensors.