Opportunity
The development of flexible piezoelectric materials has been driven by the growing demand for energy harvesting and self-powered sensors in portable electronics, wearable devices, and soft robotics. Traditional piezoelectric materials face a critical trade-off: bulk ceramics like lead zirconate titanate (PZT) exhibit high piezoelectric coefficients but lack flexibility, while polymers like polyvinylidene fluoride (PVDF) offer flexibility but suffer from significantly lower piezoelectric performance. Existing ceramic-polymer composites often incorporate low-dimensional ceramic fillers (e.g., nanoparticles or nanowires) dispersed randomly in a polymer matrix. However, these designs suffer from discontinuous stress transfer, poor mechanical durability, and limited energy conversion efficiency due to the lack of structural connectivity in the ceramic phase. Additionally, methods like freeze-casting or foam-based composites struggle with excessive shrinkage (up to 150%), cracking, and difficulty in tuning pore structures. These limitations hinder their practical applications in devices requiring both high piezoelectric output and mechanical resilience. The present patent addresses these challenges by introducing a novel 3D interconnected ceramic framework derived from organic templates, enabling superior flexibility without sacrificing piezoelectric performance.
Technology
The patent discloses a flexible piezoelectric composite comprising a 3D interconnected ceramic framework based on porous organic templates (e.g., paper, textile, wood, bamboo) infiltrated with a dual-polymer matrix. The innovation lies in the fabrication method: (1) A sol-gel process mixed with surface-modified PZT powders is used to create a dense ceramic framework with minimal shrinkage (~50%), overcoming the cracking issues of prior art. (2) The framework is coated with a stiff polymer (e.g., PVDF) for mechanical support and infiltrated with a soft elastomer (e.g., PDMS) for elasticity, achieving a low Young’s modulus (<20 mpa).="" (3)="" the="" 3d="" connectivity="" of="" the="" ceramic="" phase="" ensures="" efficient="" stress="" transfer,="" enhancing="" piezoelectric="" response="" under="" multiple="" deformation="" modes="" (compression,="" bending).="" key="" advancements="" include="" anisotropic="" piezoelectricity="" tailored="" by="" template="" choice="" (e.g.,="" wood’s="" aligned="" pores="" vs.="" textile’s="" woven="" structure),="" high="" filler-to-matrix="" ratio="" (="">2:1), and polarization under an electric field (>15 kV/mm) to activate piezoelectricity. This design achieves outputs of 20 V under tapping forces and 5 V under bending—surpassing conventional composites—while maintaining durability over 100,000 cycles.
Advantages
- High Piezoelectric Output: Generates up to 20 V under mechanical stress, outperforming traditional composites.
- Flexibility: Young’s modulus <20 mpa="" enables="" bending/stretching="" without="" cracking.="">
- Low Shrinkage: ~50% volume reduction during sintering vs. ~150% in prior methods.
- Anisotropic Response: Tunable via organic templates (e.g., wood for directional sensitivity).
- Durability: Stable performance over 100,000 mechanical cycles.
- Scalable Fabrication: Uses cost-effective organic templates and sol-gel processes.
Applications
- Energy Harvesting: Powering wearables/IoT devices from body motion or vibrations.
- Self-Powered Sensors: Pressure/shear sensors for robotics or medical monitoring.
- Soft Robotics: Actuators with integrated sensing capabilities.
- Wearable Electronics: Flexible strain sensors for health tracking.
- Structural Health Monitoring: Embedded sensors in buildings or vehicles.
