With the deep integration and development of artificial intelligence and Internet of Things (IoT) technologies, flexible and stretchable strain sensors have garnered widespread attention due to their potential applications in human motion detection, medical diagnostics, human-computer interaction, and electronic skin. Strain sensors operate by converting mechanical stimuli into electrical signals-such as resistance or capacitance-through various sensing mechanisms. Among these, resistive strain gauges have become a research hotspot due to their high sensitivity, low cost, simple structure, and ease of reading.
Currently, one of the common strategies for fabricating high-performance flexible strain sensors involves introducing fine microstructures-such as micropyramids, folds, and microcolumns-onto the surface of the elastic substrate to achieve higher sensitivity and lower detection limits. However, traditional microstructure fabrication methods-such as molding, photolithography, and self-assembly-often involve cumbersome, time-consuming, and costly processes, limiting the rapid fabrication and large-scale application of sensors. In contrast, laser processing technology offers a new approach to the manufacturing of flexible electronic devices due to its advantages of high speed, high efficiency, mask-free operation, low cost, and high flexibility. Nevertheless, relying solely on laser processing strategies to achieve strain sensors that simultaneously possess high sensitivity, high stretchability, high linearity, fast response, low hysteresis, and long-term stability remains a significant challenge. How to achieve the synergistic optimization of these properties under simple, low-cost fabrication conditions remains a core challenge in current research.
The team led by Xie Xiaozhu from the School of Mechanical and Electrical Engineering at Guangdong University of Technology has proposed a simple, cost-effective, and efficient method to develop a strain sensor with high sensitivity, stretchability, and good stability. By combining laser direct writing technology with 3D printing, they successfully fabricated a P-PDMS flexible strain sensor.
This study developed a low-cost and scalable manufacturing strategy that combines laser direct writing and 3D printing technology to prepare a variety of patterned PDMS (P-PDMS) flexible strain sensors. We optimized manufacturing parameters such as laser processing and 3D printing to prepare sensors with the highest sensitivity over a wide strain range. Under the process parameters of scanning frequency 100kHz, pulse energy 1.46μJ, scanning speed 5mm/s and printing speed 2.5mm/s, the prepared sensor with composite microstructure exhibits highly linear sensitivity. Notably, the sensitivity of the composite microstructure (PCM) flexible strain sensor is 159% higher than that of the patterned single microstructure (PSLM) sensor and 339% higher than that of the unpatterned sensor. In terms of dynamic response, the sensor has a response time of 140ms (compared to 362ms for the patternless sensor and 244ms for the single microstructure sensor), with a hysteresis coefficient as low as 0.023 and excellent cycle stability. In addition, it exhibits stable temperature response and an ultra-low detection limit of 0.0125%. Therefore, our strain sensors can be used to detect a variety of human movements, including movements of fingers, wrists, knees, and elbows. The laser direct writing method also has the advantages of simplicity, efficiency, and low cost, and shows great potential in the field of wearable electronic devices.
