Tunable ionic pressure sensor based on 3D printed ordered hierarchical mesh structure

Sensing devices sense the desired stimulus based on several transduction mechanisms, including capacitance, piezoresistivity and piezoelectricity. The choice of the transduction mechanism depends on several factors, i.e. sensitivity range, stability, design, and power consumption. In recent years, the study and development of flexible pressure sensors, in particular, have focused on achieving broad sensing range, high sensitivity and tunable fabrication methods. Most of the reported flexible pressure sensors are based on the capacitance transduction mechanism that perceives pressure stimulus as a change in the dielectric layer thickness. Nevertheless, the performance of these flexible capacitive pressure sensors is still far from achieving the requisite sensitivity and sensing range that limits their applications.

Ionic pressure sensors, based on ionic gel, have been recently identified as promising candidates for achieving tunable performance. Despite the remarkable sensitivity and sensing range, the currently available fabrication methods are expensive, complicated and offer poor flexibility that compromises the fabrication of a tunable pressure sensor. To this note, a team of researchers at Tianjin University: Professor Qiang Zou, Zhuomin Ma, Dr. Shihao Li, Zhimin Lei (Graduate candidate) and Qi Su (PhD candidate) fabricated and demonstrated the feasibility of a tunable ionic pressure sensor based on the dielectric layer with ordered hierarchical mesh structures (OHMS). Their main objective was to tune the sensor performance. Their work is currently published in the journal, Sensors and Actuators A: Physical.

In their approach, a simple and adaptable 3D printing technique was utilized to fabricate the ordered hierarchical mesh structure layers. This technique comprised of a programmable controller that enabled low-cost printing of the dielectric layers with various shapes and sizes at high resolution. Finally, the practical applicability of the fabricated sensor was assessed in different practical applications, including breathing, wrist pulse and detection of solvent evaporation.

The authors found out that the high performance of the fabricated sensor highly depended on the ordered hierarchical mesh structures and the electrical double layers with remarkable interface capacitance formed by the contact between the dielectric layer and the electrode. The sensor exhibited a broad pressure sensing range from 1Pa – 400kPa as well as a high sensitivity of 72.86 kPa^-1 in the ultralow pressure range below 0.4kPa. Moreover, the sensor exhibited additional advantages, including high stability and faster relaxation and response time. Furthermore, the feasibility of the sensor was successfully validated in different practical applications.

In a nutshell, a new approach for tunning and enhancing the performance of ionic pressure sensors based on ordered hierarchical mesh structures was presented. As such, excellent performance ranging from sensitivity, sensing range, response time, stability was reported. In a statement to Advances in Engineering, the authors said that the simple and tunable approach presented in the study would provide a new direction for the fabrication of tunable, and high-performance flexible pressure sensors for various applications such as health-monitoring devices and human interface systems.