Piezoionic Amplification Strategy for Self-powered Mechanical Sensors

Applications such as environmental monitoring, implantable biosensors, and security are major driving forces for deploying large numbers of interoperating sensors. Often, these sensor nodes are distributed across vast areas or implanted in inaccessible locations, making it crucial for them to operate independently, sustainably, and without maintenance. However, most current sensors require power sources, posing significant challenges. For instance, replacing batteries in devices implanted in the body or located in remote areas can be inconvenient or even prohibitive. Additionally, the chemicals used in batteries are often environmentally unfriendly. Therefore, achieving self-powered operation for sensors is critically important for a wide range of applications from both economic and sustainability perspectives.One straightforward strategy is for the sensor to generate an electrical signal in response to an environmental stimulus. These "generative sensors" can operate without batteries. Piezoionic sensors are emerging as a major class of devices that offer such self-powered pressure-sensing capabilities. Although significant advances have been made in the microstructure, composition, and biocompatibility of piezoionic pressure sensors, no strategy has been proposed to amplify the ionic separation that ultimately leads to a larger piezoionic voltage output.In this project, we propose to enhance the voltage response of piezoionic pressure sensors through piezoionic amplification. This amplification can be achieved by increasing the difference in mobility between anions and cations. A key innovative aspect of this project is the explicit enhancement of pressure-induced ionic separation, which has not been previously reported. To realize this strategy, we propose using crown ether, a ringshaped molecule specifically selected to diameter-match the ionic carrier (e.g., Na+) to assist in solvation, thereby enhancing ionic mobility. We plan to undertake four main tasks: (1) materials synthesis, (2) piezoionic amplification engineering, (3) device fabrication, and (4) application demonstration. To substantiate feasibility, our research methodology is supported by extensive preliminary results. Preliminary experiments have already shown a 30-fold piezoionic amplification in a polyvinyl alcohol (PVA) hydrogel system due to crown ether grafting, which is highly encouraging and will be further improved in this project.The successful completion of this project will lead to an effective approach for developing mechanical sensors and piezoionic devices that are simultaneously soft and highly sensitive. Most importantly, the ability for sensors to be self-powered will eliminate system complexity, operational overhead, and environmental impacts associated with battery-powered operation. The capabilities achieved will enable advanced designs and new applications in wearable electronics, personal health monitoring, soft robotics, and beyond.