Researchers have found a droplet microfluidics technique to produce microspheres with a high electroactive-EA phase that can be used for favorable applications in the fabrication of piezoelectric devices that serve as self-powered sensors to monitor various physiological signals.
Polymer microspheres, notable for their increased surface area and enhanced interface capabilities, have attracted considerable interest. However, current methods for their production have drawbacks such as size irregularities and high energy requirements. To overcome these drawbacks, microfluidic techniques have emerged that offer advantages such as tunability, size and shape control, efficiency, etc. In the past years, microspheres of PVDF have been produced via microfluidics but the presence of high EA phase in them remains a challenge.
Researchers at the Institute of Nano Science and Technology (INST), Mohali, an autonomous institute of the Department of Science and Technology, have presented droplet microfluidics technology coupled with off-chip thermal polymerization technique to synthesize tunable polyvinylidene fluoride (PVDF) microspheres to engineer a highly EA phase. The obtained microspheres exhibited uniformity and homogeneity with a narrow size distribution.
The high EA phase of the microspheres was engineered through the flow rate of oil and polymer solution in the microfluidic device and extensive characterization was performed to verify the piezoelectric response of the microspheres.
The team brought uniformity and size control (126-754 µm) to the microspheres. By adjusting the flow rate and optimizing the reaction temperature, the EA phase was increased by about 82%. Additionally, artificial intelligence (AI) was used as a key tool in enabling accurate predictions for microsphere diameters and phases, reducing the need for extensive laboratory optimization before droplet production in microfluidics. The work was recently published in the Journal of Chemical Engineering, Elsevier.
As a proof of concept, the researchers explored the application of PVDF microspheres in the development of a flexible piezoelectric device that can be seamlessly integrated with various parts of the human body such as elbow, knee, etc. through adaptive fitting. It undergoes different degrees of compression at different rates depending on the specific body motion, thereby utilizing the energy generated from body movements that would otherwise be wasted. The electrical response generated proved to be sufficient, providing enough output voltage (around 23V) to operate low-power devices.
The integration of this technology into application-friendly devices opens new avenues for efficient energy harvesting from human motion, paving the way for sustainable and self-sufficient wearable devices. This method offers several advantages, including simplicity, cost-effectiveness, high efficiency, and controllability, making it highly significant for applications in the biomedical field, self-powered devices, and beyond. This research highlights the collaborative potential of microfluidics, polymer science, and AI in fostering the development of intelligent materials.