Patterned Magnetofluids via Magnetic Printing and Photopolymerization for Multifunctional Flexible Electronic Sensors

One-step 3D shrinking method to prepare robust and multifunctional flexible strain sensor with brain cortex-like wrinkled structured

At the current stage of rapid development in flexible electronics technology, flexible strain sensors face the challenge of integrating multiple functions while maintaining high sensitivity, a wide strain response range, and stable sensing performance in complex and harsh environments. In response to this challenge, we propose a facile and transfer-free one-step 3D-shrinking approach inspired by the wrinkled structure of the brain cortex. This method involves spraying a uniform conductive layer onto a pre-inflated latex balloon and gradually releasing the air, which induces the formation of an intertwined, meandering conductive layer that resembles a brain cortex-like wrinkled structure. The conductive layer at the wrinkles is interlocked and engaged with the latex substrate, thus achieving a robust anchoring effect and effectively balancing the mechanical properties, surface wettability, and sensing performance of the sensor. The wrinkled conductive layer forms a hierarchical micro-nano structure, endowing the sensor with self-cleaning functionality and a water contact angle (WCA) of up to 168.4°. Meanwhile, the sensor exhibits a rapid response time of 100 ms, a gauge factor (GF) up to 2653.3, and a broad strain detection range of 0.1-191 %. More importantly, the sensor maintains excellent electrochemical stability and superhydrophobic durability even after being subjected to water scouring, finger wiping, ultrasonic cleaning, and exposure to humid or corrosive environments. In addition, after undergoing a stretch-release cyclic test lasting up to 30,000 s, the sensor demonstrates regular and repeatable resistance changes, and the wrinkled structure remains intact. Its compact and lightweight design allows it to be easily assembled for dynamically monitoring the full range of human body movements (from subtle pulse beats to large joint movements), air flow, liquid droplet falling height, and variable weather conditions. Consequently, this brain cortex-like wrinkled structure sensor offers a simple and universal fabrication method for high-performance strain sensors, providing valuable insights for advancing the next generation of flexible electronics.

Research Progress and Application of Multimodal Flexible Sensors for Electronic Skin

In recent years, wearable electronic skin has garnered significant attention due to its broad range of applications in various fields, including personal health monitoring, human motion perception, human-computer interaction, and flexible display. The flexible multimodal sensor, as the core component of electronic skin, can mimic the multistimulus sensing ability of human skin, which is highly significant for the development of the next generation of electronic devices. This paper provides a summary of the latest advancements in multimodal sensors that possess two or more response capabilities (such as force, temperature, humidity, etc.) simultaneously. It explores the relationship between materials and multiple sensing capabilities, focusing on both active materials that are the same and different. The paper also discusses the preparation methods, device structures, and sensing properties of these sensors. Furthermore, it introduces the applications of multimodal sensors in human motion and health monitoring, as well as intelligent robots. Finally, the current limitations and future challenges of multimodal sensors will be presented.