Smart piezoresistive tunnelling composite for flexible robotic sensing skin

Stassi, Stefano; Canavese, Giancarlo; Cosiansi, Fernando; Gazia, Rossana; Fallauto, Carmelo; Corbellini, Simone; Pirola, Marco; Cocuzza, Matteo

doi:10.1088/0964-1726/22/12/125039

Cited by 30 publications

(26 citation statements)

References 30 publications

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“…Nanoparticles, whose dimensions are within the range of 10 −8 and 10 −6 meters, are made of conductive materials such as copper or nickel. They allow electrical conduction between electrodes although thin films of the polymer matrix avoid direct physical contact among them [21][22][23]. Let s be the average interparticle distance inside of the CPC, which changes with the applied axial stress due to polymer deformation, so it can be stated that s = s(σ), where σ is the mechanical stress (σ) over the sensor-sensitive area (SSA).…”

Section: Deformation Versus Stress Curves: a Proposed Complementary Amentioning

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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Section: Deformation Versus Stress Curves: a Proposed Complementary Amentioning

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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“…A broad range of materials have been evaluated as the non-conductive element in the fabrication of SSA, but elastomers, rubbers and polydimethylsilicone (PDMS) are the preferably chosen polymers as reported by Stassi et al [ 3 ]. Likewise, conductive particles can be obtained from different metals, such as Nickel or Cooper, with particles sizes within the range of tens of nanometers up to a few micrometers [ 4 , 5 ]. Carbon black and carbon nanotubes have also been implemented as conductive phases in the insulating matrix [ 6 , 7 ].…”

Section: Introductionmentioning

confidence: 99%

Underlying Physics of Conductive Polymer Composites and Force Sensing Resistors (FSRs) under Static Loading Conditions

Paredes-Madrid

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Matute

et al. 2017

Sensors

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Conductive polymer composites are manufactured by randomly dispersing conductive particles along an insulating polymer matrix. Several authors have attempted to model the piezoresistive response of conductive polymer composites. However, all the proposed models rely upon experimental measurements of the electrical resistance at rest state. Similarly, the models available in literature assume a voltage-independent resistance and a stress-independent area for tunneling conduction. With the aim of developing and validating a more comprehensive model, a test bench capable of exerting controlled forces has been developed. Commercially available sensors—which are manufactured from conductive polymer composites—have been tested at different voltages and stresses, and a model has been derived on the basis of equations for the quantum tunneling conduction through thin insulating film layers. The resistance contribution from the contact resistance has been included in the model together with the resistance contribution from the conductive particles. The proposed model embraces a voltage-dependent behavior for the composite resistance, and a stress-dependent behavior for the tunneling conduction area. The proposed model is capable of predicting sensor current based upon information from the sourcing voltage and the applied stress. This study uses a physical (non-phenomenological) approach for all the phenomena discussed here.

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“…When manufacturing CPCs, materials such as: rubber, elastomer, and Polydimethylsiloxane (PDMS) are the preferably chosen solutions for the insulating phase [ 2 , 3 , 4 ]. Conductive particles are typically obtained from metals such as Nickel or Cooper [ 5 , 6 ], but more recently, carbon black or carbon nanotubes have been also employed as the conductive phase in CPCs [ 7 , 8 ]. Particle sizes for the conductive filler are typically between the range of tens of nanometers up to a few micrometers.…”

Section: Introductionmentioning

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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Smart piezoresistive tunnelling composite for flexible robotic sensing skin

Cited by 30 publications

References 30 publications

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

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

Underlying Physics of Conductive Polymer Composites and Force Sensing Resistors (FSRs) under Static Loading Conditions

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

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