Opportunity
Traditional wearable pressure sensors face significant limitations in sensitivity, flexibility, and biocompatibility, which hinder their widespread adoption in critical fields such as healthcare, human-machine interaction, and robotics. Conventional sensors often rely on external power sources and dual-electrode designs, reducing their operational lifespan and integration efficiency. Additionally, the materials used—typically synthetic polymers or metals—lack the necessary biocompatibility and stretchability to conform safely to human skin. These shortcomings limit their use in long-term physiological monitoring or seamless integration with wearable devices. The growing demand for advanced health monitoring systems and smart wearables underscores the need for a sensor that combines high sensitivity, self-powering capability, and biocompatibility.
Technology
This patent introduces a flexible pressure sensor with a sandwich structure comprising two encapsulation layers and a bio-based intermediate layer. The key innovation lies in the intermediate layer’s composition, which includes polyvinyl alcohol (PVA), inorganic salts (e.g., calcium oxide), keratin, and water. Keratin, a natural protein, enhances the sensor’s sensitivity and linearity by amplifying triboelectric output, while PVA and inorganic salts improve mechanical properties. The encapsulation layers, made of fatty-aromatic random copolyester (Ecoflex), feature microstructured surfaces (e.g., rectangular protrusions) to enhance pressure-responsive friction.
The sensor operates via triboelectric effects between the intermediate and encapsulation layers, enabling self-powering without external energy input. Its single-electrode design simplifies integration into wearable systems. The fabrication process involves 3D-printed molds for precise control over layer thickness and microstructure, ensuring scalability.
Advantages
- High sensitivity (0.225 V/kPa) and linearity (R² = 0.988), outperforming traditional sensors (e.g., 0.081 V/kPa for PVA-only designs).
- Self-powered functionality via triboelectric effects, eliminating the need for external power.
- Excellent flexibility and stretchability (up to 200% strain), ideal for wearable applications.
- Biocompatibility due to keratin and Ecoflex, enabling safe skin contact.
- Simple, scalable fabrication using 3D-printed molds and solution casting.
Applications
- Wearable health monitoring: Real-time tracking of pulse, respiration, or muscle activity.
- Human-machine interfaces: Gesture recognition (e.g., finger motion tracking for VR/AR).
- Soft robotics: Pressure feedback for adaptive grippers or prosthetics.
- Smart textiles: Integrated sensors for athletic performance monitoring.
