A flexible, highly sensitive pressure sensor combines resistive and capacitive elements using a porous carbon nanotube–Eco flex material. It accurately detects a wide range of pressures, is easy to fabricate, and suits diverse applications like medical monitoring and environmental sensing.
Pressure sensing technology plays a crucial role in numerous applications, ranging from medical diagnostics and wearable devices to environmental monitoring and industrial automation. Accurate and reliable measurement of pressure variations is essential for capturing subtle physiological signals, ensuring safety in mechanical systems, and enabling responsive control in smart environments. As the demand for more versatile and high-performance sensors grows, there is an increasing need for pressure sensors that offer exceptional sensitivity, flexibility, and a wide dynamic range to accommodate diverse and evolving requirements.
Current pressure sensing approaches often struggle to balance sensitivity and range, limiting their effectiveness across different applications. Traditional capacitive sensors, for instance, may exhibit high sensitivity within a narrow pressure band but fail to maintain performance under varying load conditions or extended usage. Additionally, many existing sensors require complex fabrication processes and specialized equipment, hindering scalability and integration into flexible or wearable platforms. Mechanical rigidity and lack of conformability further restrict their applicability in scenarios where adaptation to curved or dynamic surfaces is essential.
These limitations underscore the need for advanced pressure sensing solutions that can overcome existing challenges by delivering consistent performance, ease of manufacturing, and adaptability to a wide spectrum of pressure-related tasks.
A highly sensitive, flexible hybrid response pressure sensor (HRPS) combines piezoresistive and piezo capacitive properties to detect pressures ranging from 0.07 Pa up to 125 kPa. The sensor features a porous nanocomposite (PNC) made of carbon nanotubes dispersed in Eco flex rubber, forming an open-cell structure with approximately 86% porosity. An ultrathin 500 nm polymethyl methacrylate (PMMA) insulating layer is positioned between the PNC and one electrode to facilitate capacitive behavior. The fabrication process involves mixing hydroxyl-functionalized carbon nanotubes with Eco flex, applying the mixture to a nickel foam template, curing, and removing the template through acid etching. Flexible gold/polyimide electrodes sandwich the PNC, and the device can be packaged with medical-grade dressings for enhanced biocompatibility and flexibility.
The HRPS stands out due to its exceptional sensitivity and broad pressure range, achieved through the synergistic combination of its porous structure and dual sensing mechanisms. Unlike traditional capacitive sensors, the high porosity of the PNC amplifies the sensor’s responsiveness to pressure changes, while the integration of both piezoresistive and piezo capacitive properties ensures accurate detection across multiple orders of magnitude. The straightforward fabrication process using common laboratory equipment enhances scalability and cost-effectiveness. Additionally, the sensor maintains high sensitivity under significant preload conditions and demonstrates versatility in applications, from subtle biological measurements to monitoring high-pressure events. A theoretical model further optimizes the nanocomposite resistance for maximum sensitivity, ensuring reliable and robust performance in diverse environments.
https://patents.google.com/patent/WO2023010087A1/en?oq=PCT%2fUS2022%2f074270