Framework for a Calibration-Less Operation of Force Sensing Resistors at Different Temperatures

Paredes-Madrid, Leonel; Matute, Arnaldo; Peña, Ángela María

doi:10.1109/jsen.2017.2706697

Cited by 12 publications

(11 citation statements)

References 32 publications

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“…And last, a tailored test bench was assembled to handle up to sixteen sensors simultaneously. The test bench has been thoroughly described in previous authors’ works [ 30 , 47 ], and therefore, only a brief description is here presented.…”

Section: Resultsmentioning

confidence: 99%

Underlying Physics of Conductive Polymer Composites and Force Sensing Resistors (FSRs). A Study on Creep Response and Dynamic Loading

et al. 2017

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Force Sensing Resistors (FSRs) are manufactured by sandwiching a Conductive Polymer Composite (CPC) between metal electrodes. The piezoresistive property of FSRs has been exploited to perform stress and strain measurements, but the rheological property of polymers has undermined the repeatability of measurements causing creep in the electrical resistance of FSRs. With the aim of understanding the creep phenomenon, the drift response of thirty two specimens of FSRs was studied using a statistical approach. Similarly, a theoretical model for the creep response was developed by combining the Burger’s rheological model with the equations for the quantum tunneling conduction through thin insulating films. The proposed model and the experimental observations showed that the sourcing voltage has a strong influence on the creep response; this observation—and the corresponding model—is an important contribution that has not been previously accounted. The phenomenon of sensitivity degradation was also studied. It was found that sensitivity degradation is a voltage-related phenomenon that can be avoided by choosing an appropriate sourcing voltage in the driving circuit. The models and experimental observations from this study are key aspects to enhance the repeatability of measurements and the accuracy of FSRs.

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Section: Resultsmentioning

confidence: 99%

Underlying Physics of Conductive Polymer Composites and Force Sensing Resistors (FSRs). A Study on Creep Response and Dynamic Loading

et al. 2017

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“…Measuring capacitance is not as straightforward as measuring resistance, which can be done with inexpensive and simple circuitry [35,36] [12,14]. However, the most concerning drawback of those approaches was costs.…”

Section: Capacitance Measurement With a Lm555 In Modified Astable Opementioning

confidence: 99%

“…Loading and unloading forces could have been applied in order to acquire the frequency data for several force levels. Detailed information about the workbench can be found in [31,36]. Figure 17(a) shows that a linear fitting for the graphed characteristic is not appropriate, which suggests that this approach is not to be the most adequate for the obtained data.…”

Section: Journal Of Sensorsmentioning

confidence: 99%

A Novel and Inexpensive Approach for Force Sensing Based on FSR Piezocapacitance Aimed at Hysteresis Error Reduction

et al. 2018

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Force-sensing resistors (FSRs) are inexpensive alternatives to load cells. They are suitable for applications where noninvasive devices are needed to measure force, stress, or pressure. However, they have been proved to be hysteresis prone and offer nonrepeatable readings due to their highly voltage-dependent electrical resistance. A piezocapacitive effect has been found as an alternative phenomenon that is able to offer force-dependent readings of capacitance with less hysteresis error. Also, this capacitance is not dependent on voltage, which also improves repeatability in force measurements. Since measuring capacitance is more expensive than resistance, the least costly conditioning circuitry is desired. An inexpensive alternative using an LM555 that oscillates depending on capacitance is here presented. Hysteresis and repeatability errors have been reduced for a widespread-used force-sensing resistor brand.

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“…A detailed description of the mechanical test bench has been presented by the authors in Reference [37], so only a brief description is next presented. The mechanical test bench is capable of handling multiple sensors using a sandwich-like configuration, see Figure 4.…”

Section: Experimental Setup Results and Discussionmentioning

confidence: 99%

“…The circuits shown in Figures 3 and 5 can drive a single FSR, but multiple FSRs can be simultaneously handled if multiplexers are employed [22,37]. Before proceeding with the experimental results, it is necessary to discuss the relationship between the applied stress, σ, and the parameters s, R FSR , C FSR , and f. The inter-particle separation, s, is reduced for larger stresses, and consequently, Equation (2) and Equations (4)-(6) predict a lower R FSR for incremental stresses.…”

Section: Experimental Setup Results and Discussionmentioning

confidence: 99%

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

et al. 2018

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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.

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Framework for a Calibration-Less Operation of Force Sensing Resistors at Different Temperatures

Cited by 12 publications

References 32 publications

Underlying Physics of Conductive Polymer Composites and Force Sensing Resistors (FSRs). A Study on Creep Response and Dynamic Loading

Underlying Physics of Conductive Polymer Composites and Force Sensing Resistors (FSRs). A Study on Creep Response and Dynamic Loading

A Novel and Inexpensive Approach for Force Sensing Based on FSR Piezocapacitance Aimed at Hysteresis Error Reduction

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

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