Contents I. Introduction
A bend sensor, sometimes known as a flex or strain sensor, is a device that detects the amount of deflection or bending. Flex sensors are employed in various research applications, including computer interfaces, rehabilitation, security systems, and music interfaces [1]–[3]. There are several types of such sensors: resistive [4], optical [5], and capacitive devices [6]. In particular, the strain-resistant effect is promising for use in bending sensors [7]–[9]. The essence of the piezoresistive effect is to change the electrical resistivity of conductive or semiconductive materials during their deformation. When a conductive material is deformed, its geometrical sizes are changed. When semiconductor material is deformed, the structure of the energy bands in the crystal is varied. This causes the changing of bandgap, concentration of current carriers, and their effective mass.
