Highly sensitive capacitive pressure sensor with elastic metallized sponge

Just like skin that regulates human interaction with the environments, sensors form the basis of artificial intelligence as they give meaning to various artificial components such as robots. To develop highly efficient sensors exhibiting natural skin characteristics, researchers have explored a variety of transduction principles including electromagnetic, capacitive, piezoelectric and optoelectronic principles which require the development of more advanced materials. Among the known tactile sensors, capacitive sensors have attracted significant research attention owing to their excellent resolution, sensitivity, and structural properties. It measures the capacitance due to perceived changes in the permittivity and physical size induced by physical and/or chemical stimulus. A good example is the pressure detection. To enhance the performance and efficiency of capacitive sensors, better strategies for the design of dielectric layer and electrode structures are highly desirable.

To this note, researchers from Fuzhou University in China: Youzhi Zhang, Zhengkang Lin, Xingping Huang, Xiaojun You, Dr. Jinhua Ye and Dr. Haibin Wu developed a new design strategy for the capacitive pressure sensor. Unlike the previous studies where micro-structured dielectric layers were used to enhance the sensitivity of capacitive sensors, the authors presented an innovative approach based on elastic metalized sponges as the elastic porous electrode to achieve the same goal. The feasibility of this capacitive pressure sensors in accurately measuring low pressures is investigated. The research work is currently published in the journal, Smart Materials and Structures.

The elastic porous electrode is highly sensitive to low pressure and was effectively used to detect low pressures due to the capacitance change caused by the change in the contact area between the dielectric layer and the elastic porous electrode. Compared with the traditional capacitive sensor using an insulative polyurethane sponge as the dielectric, the baseline capacitance of the sensor of the same size can increase by 10 times, and it has a better signal-to-noise ratio. Also, the good mechanical properties of the nickel-plated polyurethane sponge ensured that the sensor exhibited good mechanical properties as compared to its traditional counterparts.

To validate the sensor measurement abilities, a practical experiment was necessary. For this reason, the senor samples were fabricated together with its signal acquisition and processing system. The sensor was then installed on a rigid machine hand of UR5(Universal Robotics) robot that was thereafter tested for grabbing experiments. As per the results, the authors observed that the capacitive pressure sensor exhibited excellent performance similar to human fingers as far as the grasping of fragile, ultra-low and ultra-light modulus objects is concerned.

In summary, the research team from Fuzhou University presented landmark research finding for enhancing the sensitivity and efficiency of low-pressure capacitive sensors utilizing elastic metalized sponge-based dielectric materials. The novel capacitive sensor exhibited high sensitivity to low pressure and thus was successfully used in grasping experiments on a robot. Additionally, the low-cost and robust approach involves simple manufacturing processes, unlike conventional traditional manufacturing methods. In a statement to Advances in Engineering (AIE), Dr. Haibin Wu, the corresponding author stated that the study will thus expand tactile sensing and robotic electronic skin related applications.