Interdigitated capacitive proximity sensor with varied space electrode structure

Abstract

Embodiments related to a capacitive proximity sensor with a variable spacing electrode structure, which is suited to a non-destructive testing operation, such as the detection of dielectric properties of the polymer materials with a thickness decreases gradually structure. The designed sensor includes a driving electrode, a sensing electrode, a substrate, a guarding electrode and a lead connector. The driving and sensing electrodes include several interdigitated fingers, which are arranged alternately in sequence, based on the characteristic of the thickness decreases gradually structure of the MUT, the width of the electrodes and spacing between two adjacent electrodes in each unit are optimized individually. Namely, under the condition of ensuring penetration depth, the electrode width is made as large as possible to achieve maximum signal strength and detection sensitivity. Compared with the traditional ES-IDE structure capacitive proximity sensor, the newly designed VS-IDE capacitive sensor increases the effective electrode area, which increases the signal strength and measurement sensitivity directly. Besides, the electric field lines of the designed sensor are confined within the thickness gradually changed materials under test mostly as expected simultaneously.