Validation of Screen-Printed Electronic Skin Based on Piezoelectric Polymer Sensors

Abstract

This paper proposes a validation method of the fabrication technology of a screen-printed electronic skin based on polyvinylidene fluoride-trifluoroethylene P(VDF-TrFE) piezoelectric polymer sensors. This required researchers to insure, through non-direct sensor characterization, that printed sensors were working as expected. For that, we adapted an existing model to non-destructively extract sensor behavior in pure compression (i.e., the d33 piezocoefficient) by indentation tests over the skin surface. Different skin patches, designed to sensorize a glove and a prosthetic hand (11 skin patches, 104 sensors), have been tested. Reproducibility of the sensor response and its dependence upon sensor position on the fabrication substrate were examined, highlighting the drawbacks of employing large A3-sized substrates. The average value of d33 for all sensors was measured at incremental preloads (1–3 N). A systematic decrease has been checked for patches located at positions not affected by substrate shrinkage. In turn, sensor reproducibility and d33 adherence to literature values validated the e-skin fabrication technology. To extend the predictable behavior to all skin patches and thus increase the number of working sensors, the size of the fabrication substrate is to be decreased in future skin fabrication. The tests also demonstrated the efficiency of the proposed method to characterize embedded sensors which are no more accessible for direct validation.

Full-hand electrotactile feedback using electronic skin and matrix electrodes for high-bandwidth human–machine interfacing

“…The whole structure was screen printed on a transparent and flexible PET (175 µm thick) substrate. The fabrication technology was presented and validated in [67]. It is worth noting that piezoelectric polymer sensors have a bandwidth integrating those of all mechanoreceptors in the human skin.…”

Flexible ferroelectric wearable devices for medical applications

“…Screen printed wearable piezoelectric devices have been developed for monitoring physiological signals ( Fares et al., 2020 ; Gonçalves et al., 2019 ; Laurila et al., 2019 ; Sato et al., 2019 ). Sekine et al.…”

“…Fares et al. ( Fares et al., 2020 ) demonstrated a skin attachable piezopolymer screen-printed sensor as shown in Figure 3 . A variety of skin patches were designed and developed to provide a sensing capability to a glove and prosthetic hand.…”

“…A variety of skin patches were designed and developed to provide a sensing capability to a glove and prosthetic hand. The average piezoelectric charge constant for all sensors was measured at incremental preloads (1–3 N) and are presented in a detailed table that can be found in the paper ( Fares et al., 2020 ).

Figure 3 Screen printed PVDF-based wearable sensing device (A) Sketch of the sensing patch.

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Computationally Light Algorithms for Tactile Sensing Signals Elaboration and Classification

“…In our tactile system, we utilized low-cost sensing patches based on the P(VDF-TrFE) (poly(vinylidene fluoride trifluoroethylene)) piezoelectric polymer sensors [14]. This type of sensor generates charges when subjected to external stimuli.…”