An Optoelectronics-Based Compressive Force Sensor with Scalable Sensitivity

Abstract

There is an increasing need to accurately measure compressive force for biomedical and industrial applications. However, this need has not been fully addressed, as many sensors are bulky, have high power requirements, and/or are susceptible to electromagnetic interference. This paper presents an optoelectronics-based force sensor that can overcome the limitations of many sensors in the market. The sensor uses a light emitting diode (LED) to transmit visible broad-spectrum light into a photoresistor through an optically clear spacer on top of an elastomeric medium. In the absence of an external force, the light path is mostly blocked by the opaque elastomeric medium. Under a compressive force, the clear spacer compresses the elastomer, moving itself into the light path, and thus increasing the overall light transmission. The amount of light received by the photoresistor is used to quantify compressive force based on elastomer displacement/compression and a priori knowledge of elastomer stiffness. This sensing scheme was tested under eight different configurations: two different sized sensors with four types of elastomers per size (20A neoprene, 30A neoprene, 50A neoprene, and 75A styrene–butadiene rubber (SBR)). All configurations measured force with R2 > 0.97, RMSE < 1.9 N, and sensitivity values ranging from 17 to 485 N/V. This sensing scheme provides a low-cost, low-power method for accurate force sensing with a wide force range.

Palm Gripper Measurement Device for Post-Stroke Rehabilitation Progressive Tracking

“…In the future, to improve the dependability of the FSRs, modelling the piezoelectric bender's hysteresis using the Bouc-Wen model is highly suggested. Nonetheless, major causes of hysteresis are often caused by instantaneous displacement rather than small voltage fluctuation [22]- [23]. In conclusion, from the study, there is no solid guarantee that the selected sensors were dependable for an accurate measurement of a palm gripping force, but it is a great choice to measure a small magnitude of force per surface area within a controlled condition [16].…”