Novel sensor circuit applicable to both contact detection and non-contact detection

A novel sensor circuit applicable to both contact detection and non-contact detection, comprising: a capacitor Cx, a resistor Re, a resistor Rf, a resistor R1, a resistor R2, and an operational amplifier A1. One end of the capacitor Cx is connected to a detection signal and the other end thereof is connected to a non-inverting input end of the operational amplifier A1; one end of the resistor Re is connected to the non-inverting input end of the operational amplifier A1 and the other end thereof is grounded; one end of the resistor Rf is connected to the non-inverting input end of the operational amplifier A1 and the other end thereof is connected to an output end of the operational amplifier A1; one end of the resistor R1 is connected to an inverting input end of the operational amplifier A1 and the other end thereof is grounded; one end of the resistor R2 is connected to the inverting input end of the operational amplifier A1 and the other end thereof is connected to the output end of the operational amplifier A1. The sensor has a simple circuit structure, is applicable to both contact detection and non-contact detection, can effectively avoid a change in circuit performance caused by a change in contact resistance or coupling capacitance, and can effectively reduce noise caused by the change in circuit performance.