Summary:
UCLA researchers in the Department of Materials Science and Engineering have developed a novel electroactive polymer membrane composition for interactive tactile interfaces.
Background:
Interactive tactile interfaces are soft actuators with diverse applications in medical and surgical training, actively deformable apparel, refreshable Braille displays, and more. Soft actuators generally operate by converting input stimuli into useful mechanical outputs. Phase change materials (PCMs) are an attractive component of actuation systems as they can display shape memory with actuation stemming from the dielectric elastomeric properties. PCMs provide materials the capability to change their physical states when triggered by heat. Specifically, stretchable Joule heating electrodes (JHEs) are used to induce the phase change needed for expansion or contraction of the material. Previous JHEs have been fabricated from a wide range of materials, but most were only reported to be bendable and could not retain their resistance at high strains. There is a demonstrated need for a JHE material that would allow strains greater than 100% and be stable to Joule heating at such strain levels.
Innovation:
UCLA researchers led by Professor Qibing Pei have developed a new, stretchable, patternable JHE material capable of maintaining the same operating voltage at actuated and relaxed states over more than 20,000 cycles. The researchers demonstrated that strains up to 100% did not affect the resistance of the JHE and applied voltages between 7 and 8 V increased the temperature of the material past the phase change transition temperature. The composition of the JHE ensures strain-invariant stretchability, good adhesion to the substrate, and reversible deformation. An array fabricated from the JHE and pneumatic pressure demonstrated tactile Braille cells that deformed out-of-plane by more than 0.5 mm.
Potential Applications:
• Medical and surgical training
• Drug delivery
• Deformable apparel
• Refreshable Braille displays
• Soft human-machine interactions
Advantages:
• Resistance maintained with applied strain
• Stability >20,000 cycles
• Modulus changes by 2 to 4 orders of magnitude with temperature
• Elastic modulus large enough at ambient temperature to support finger pressing force
Development-To-Date:
Technology has been described in a peer-reviewed publication and demonstrated in a prototype Braille system.
Related Papers:
J. Kim, Z. Xie, Z. Peng, H. Hong, S. Shajari, Y. Guo, H. Wu, Y. Meng, R. Plamthottam, Y. Zhu, Y. Qiu, H. Wang, A. Cheng, Q. Pei, Deformable Joule Heating Electrode Based on Hybrid Layers of Silver Nanowires and Carbon Nanotubes and its Application in a Refreshable Multi-Cell Braille Display. Adv. Funct. Mater. 2024, 2400023. https://doi.org/10.1002/adfm.202400023
Reference:
UCLA Case No. 2024-202
Lead Inventor:
Qibing Pei