Built-in Sensor System for Monitoring Internal Shear Strain and Stress Distribution in Soft Materials

Abstract

Soft robotics requires flexible sensors that can realize sensitive measurements in which rigid sensors are not viable. Every sensor requires a precise and quantitative measurement of the mechanical phenomena; however, in the field of soft robotics, the complex structure and physical properties of composite materials complicate the construction of a precise sensing model. A built-in sensor system for internal shear strain and stress distribution measurement was developed by embedding piezoelectric polyvinylidene fluoride polymer films inside an objective soft material. The shear strain sensing models were established by relating piezoelectricity and cantilever bending mechanics. For validation, the deflection of the embedded film sensors was monitored and digitized using a video camera in experiments. The shear strain sensing model was validated by evaluating the agreement between the modeled and measured physical variations with a high coefficient of determination of 0.974. Based on the linear relation of arithmetic expression of each sensing model, the calibrated results for internal shear strain and stress sensing were also successfully obtained. This paper presents a discussion of the measurement effect of this type of flexible sensor and its potential for further applications.

Smart and Multifunctional Materials Based on Electroactive Poly(vinylidene fluoride): Recent Advances and Opportunities in Sensors, Actuators, Energy, Environmental, and Biomedical Applications

“…More recently, and linking biomedicine with robotics, Li et al developed a built-in sensor system for internal shear strain and stress distribution measurement by embedding PVDF within the artificial skin of soft robotics. The determined 50 pC·mm –1 sensitivity is suitable for application in soft material strain/stress measurements and in soft robotics development.…”