Self-Compensated Driving Circuit for Reducing Drift and Hysteresis in Force Sensing Resistors

• Published in: Electronics (Basel) Vol. 7; no. 8; p. 146
• Main Authors: Paredes-Madrid, Leonel, Fonseca, Johanna, Matute, Arnaldo, Gutiérrez Velásquez, Elkin, Palacio, Carlos
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 14.08.2018
• Subjects: Capacitance; Carbon black; Circuits; Design; Drift; Hysteresis; Nanocomposites; Nanoparticles; Polymers; Resistors; Sensors; Colombia; United States > US
• ISSN: 2079-9292; 2079-9292
• DOI: 10.3390/electronics7080146

Force Sensing Resistors (FSRs) are manufactured from a blend of conductive nanoparticles dispersed in an insulating polymer matrix. FSRs exhibit large amounts of hysteresis and drift error, but currently, a great effort is placed on improving their performance through different techniques applied during sensor manufacturing. In this article, a novel technique for improving the performance of FSRs is presented; the method can be applied to already-manufactured sensors, which is a clear benefit of the proposed procedure. The method is based on driving the sensors with a modified-astable 555 oscillator, in which the oscillation frequency is set from the sensor’s capacitance and resistance. Considering that the sensor’s capacitance and resistance have opposite signs in the drift characteristic, the driving circuit provides self-compensated force measurements over extended periods of time. The feasibility of the driving circuit to reduce hysteresis and to avoid sensitivity degradation is also tested. In order to obtain representative results, the experimental measurements from this study were performed over eight FlexiForce A201-25 sensors.