Masihi Simin, Panahi Masoud, Maddipatla Dinesh, Hanson Anthony J, Bose Arnesh K, Hajian Sajjad, Palaniappan Valliammai, Narakathu Binu B, Bazuin Bradley J, Atashbar Massood Z
Department of Electrical and Computer Engineering, Western Michigan University, Kalamazoo, Michigan 49008, United States.
ACS Sens. 2021 Mar 26;6(3):938-949. doi: 10.1021/acssensors.0c02122. Epub 2021 Mar 17.
A novel porous polydimethylsiloxane (PDMS)-based capacitive pressure sensor was fabricated by optimizing the dielectric layer porosity for wide-range pressure sensing applications in the sports field. The pressure sensor consists of a porous PDMS dielectric layer and two fabric-based conductive electrodes. The porous PDMS dielectric layer was fabricated by introducing nitric acid (HNO) into a mixture of PDMS and sodium hydrogen bicarbonate (NaHCO) to facilitate the liberation of carbon dioxide (CO) gas, which induces the creation of porous microstructures within the PDMS dielectric layer. Nine different pressure sensors (PS1, PS2,..., PS9) were fabricated in which the porosity (pore size, thickness) and dielectric constant of the PDMS dielectric layers were varied by changing the curing temperature, the mixing proportions of the HNO/PDMS concentration, and the PDMS mixing ratio. The response of the fabricated pressure sensors was investigated for the applied pressures ranging from 0 to 1000 kPa. A relative capacitance change of ∼100, ∼323, and ∼485% was obtained by increasing the curing temperature from 110 to 140 to 170 °C, respectively. Similarly, a relative capacitance change of ∼170, ∼282, and ∼323% was obtained by increasing the HNO/PDMS concentration from 10 to 15 to 20%, respectively. In addition, a relative capacitance change of ∼94, ∼323, and ∼460% was obtained by increasing the PDMS elastomer base/curing agent ratio from 5:1 to 10:1 to 15:1, respectively. PS9 exhibited the highest sensitivity over a wide pressure sensing range (low-pressure ranges (<50 Pa), 0.3 kPa; high-pressure ranges (0.2-1 MPa), 3.2 MPa). From the results, it was observed that the pressure sensors with dielectric layers prepared at relatively higher curing temperatures, higher HNO concentrations, and higher PDMS ratios resulted in increased porosity and provided the highest sensitivity. As an application demonstrator, a wearable fit cap was developed using an array of 16 pressure sensors for measuring and mapping the applied pressures on a player's head while wearing a helmet. The pressure mapping aids in observing and understanding the proper fit of the helmet in sports applications.
通过优化介电层孔隙率，制备了一种新型的基于多孔聚二甲基硅氧烷（PDMS）的电容式压力传感器，用于体育领域的宽量程压力传感应用。该压力传感器由多孔PDMS介电层和两个织物基导电电极组成。多孔PDMS介电层是通过将硝酸（HNO）引入PDMS和碳酸氢钠（NaHCO）的混合物中制备的，以促进二氧化碳（CO）气体的释放，从而在PDMS介电层内诱导形成多孔微结构。制备了九个不同的压力传感器（PS1、PS2、...、PS9），通过改变固化温度、HNO/PDMS浓度的混合比例以及PDMS混合比例，改变了PDMS介电层的孔隙率（孔径、厚度）和介电常数。研究了所制备压力传感器在0至1000 kPa施加压力下的响应。通过将固化温度分别从110℃提高到140℃再提高到170℃，相对电容变化分别约为100%、323%和485%。同样，通过将HNO/PDMS浓度分别从10%提高到15%再提高到20%，相对电容变化分别约为170%、282%和323%。此外，通过将PDMS弹性体基料/固化剂比例分别从5:1提高到10:1再提高到15:1，相对电容变化分别约为94%、323%和460%。PS9在宽压力传感范围内表现出最高灵敏度（低压范围（<50 Pa），0.3 kPa；高压范围（0.2 - 1 MPa），3.2 MPa）。从结果可以看出，在相对较高的固化温度、较高的HNO浓度和较高的PDMS比例下制备介电层的压力传感器，孔隙率增加，灵敏度最高。作为应用演示器，开发了一种可穿戴的贴合帽，使用16个压力传感器阵列，用于在运动员佩戴头盔时测量和绘制施加在运动员头部的压力。压力映射有助于观察和理解头盔在体育应用中的合适贴合度。
