Bilent Sylvie, Dinh Thi Hong Nhung, Martincic Emile, Joubert Pierre-Yves
Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91120 Palaiseau, France.
Sensors (Basel). 2019 Apr 26;19(9):1968. doi: 10.3390/s19091968.
This paper reports on the study of microporous polydimethylsiloxane (PDMS) foams as a highly deformable dielectric material used in the composition of flexible capacitive pressure sensors dedicated to wearable use. A fabrication process allowing the porosity of the foams to be adjusted was proposed and the fabricated foams were characterized. Then, elementary capacitive pressure sensors (15 × 15 mm square shaped electrodes) were elaborated with fabricated foams (5 mm or 10 mm thick) and were electromechanically characterized. Since the sensor responses under load are strongly non-linear, a behavioral non-linear model (first order exponential) was proposed, adjusted to the experimental data, and used to objectively estimate the sensor performances in terms of sensitivity and measurement range. The main conclusions of this study are that the porosity of the PDMS foams can be adjusted through the sugar:PDMS volume ratio and the size of sugar crystals used to fabricate the foams. Additionally, the porosity of the foams significantly modified the sensor performances. Indeed, compared to bulk PDMS sensors of the same size, the sensitivity of porous PDMS sensors could be multiplied by a factor up to 100 (the sensitivity is 0.14 %.kPa for a bulk PDMS sensor and up to 13.7 %.kPa for a porous PDMS sensor of the same dimensions), while the measurement range was reduced from a factor of 2 to 3 (from 594 kPa for a bulk PDMS sensor down to between 255 and 177 kPa for a PDMS foam sensor of the same dimensions, according to the porosity). This study opens the way to the design and fabrication of wearable flexible pressure sensors with adjustable performances through the control of the porosity of the fabricated PDMS foams.
本文报道了对微孔聚二甲基硅氧烷（PDMS）泡沫材料的研究，该材料作为一种高可变形介电材料，用于制作专用于可穿戴设备的柔性电容式压力传感器。提出了一种可调节泡沫孔隙率的制造工艺，并对所制备的泡沫进行了表征。然后，用制备的泡沫（5毫米或10毫米厚）制作了基本的电容式压力传感器（15×15毫米方形电极），并对其进行了机电特性表征。由于传感器在负载下的响应具有很强的非线性，因此提出了一种行为非线性模型（一阶指数模型），将其与实验数据进行拟合，并用于客观评估传感器在灵敏度和测量范围方面的性能。本研究的主要结论是，PDMS泡沫的孔隙率可通过糖与PDMS的体积比以及用于制造泡沫的糖晶体尺寸来调节。此外，泡沫的孔隙率显著改变了传感器的性能。实际上，与相同尺寸的块状PDMS传感器相比，多孔PDMS传感器的灵敏度可提高至100倍（块状PDMS传感器的灵敏度为0.14%·kPa，相同尺寸的多孔PDMS传感器的灵敏度高达13.7%·kPa），而测量范围缩小了2至3倍（块状PDMS传感器的测量范围为594 kPa，相同尺寸的PDMS泡沫传感器的测量范围根据孔隙率在255至177 kPa之间）。这项研究为通过控制所制备PDMS泡沫的孔隙率来设计和制造性能可调节的可穿戴柔性压力传感器开辟了道路。
