High Performance Strain Sensor Based on Carbon Black/Graphene/Ecoflex for Human Health Monitoring and Vibration Signal Detection

Abstract

In recent years, there has been a significant surge of interest in flexible strain sensors within the domains of wearable electronics and human−computer interaction. However, as these fields continue to advance rapidly, there is an urgent need to improve the comprehensive performance of flexible strain sensors including sensitivity, sensing range, response speed, and durability. In this study, we address this issue by transferring carbon black/ graphene (CB/Gr) conductive nanocomposites onto the surface of an Ecoflex flexible substrate, which has been pretreated using sandpaper to enhance adhesion. The resulting flexible strain sensor exhibits high sensitivity, with a gauge factor of 51.4, while offering a wide sensing range of 100%. Notably, this sensor demonstrates high performance across various aspects, including a fast response time (60 ms) and excellent durability (up to 4000 stretching−releasing cycles). The versatility of this sensor is evident in its ability to effectively monitor both small strain activities, such as speech recognition, and larger strain activities, such as elbow bending. Moreover, the sensor has demonstrated outstanding performance in various application scenarios, including human health and motion condition monitoring as well as acoustic wave and vibration signals detection. Consequently, this highlights the sensor's remarkable adaptability and substantial potential for wide-range applications in these domains.

Strain Sensors for Human Movement Detection Based on Fibrous Membranes Comprising Thermoplastic Polyurethane, Ag Nanoparticles, and Carbon Nanotubes

“…The gauge factor (GF) is a crucial measure for assessing the sensitivity of strain sensors. It is determined by computing the slope of the plot from the relationship between the relative variation in resistance and the stretching strain, which can be calculated according to eq , G F = normalΔ R / R 0 ε where R 0 and ε represent the initial resistance and stretching strain, respectively. Δ R is the difference between the real-time resistance and the initial resistance.…”

Roadmap on printable electronic materials for next-generation sensors

“…Additionally, it has high compressibility, bendability, and stretchability, with low Young's modulus value in the range 0.4-3.5 MPa, thus enhancing its overall stretchability [292]. Eco-flex (soft silicone) has a simple preparation process, a tensile factor of ∼600%, and is biocompatible with human skin [293]. For applications requiring high stretchability, eco-flex is more beneficial compared to PDMS and PVDF (a 1 mm thick film of Eco-flex is more stretchable than its PDMS counterpart with similar dimensions) [294].…”