This Early Grant for Exploratory Research (EAGER) award provides funding for the development of a method for integrating highly efficient energy conversion materials onto stretchable, biocompatible rubbers which could yield breakthroughs in implantable or wearable energy harvesting systems. Being electromechanically coupled, piezoelectric crystals represent a particularly interesting subset of smart materials which function as sensors/actuators, bioMEMS devices, and energy converters. Yet, the crystallization of these materials generally requires high temperatures for maximally efficient performance, rendering them incompatible with temperature-sensitive plastics and rubbers. Overcoming these limitations by presenting a scalable and parallel process for transferring crystalline piezoelectric nanoribbons of lead zirconate titanate (PZT) from host substrates onto flexible plastics over macroscopic areas is a goal of this project.
If successful, it is anticipated that this work will have a substantial positive effect on the science of piezoelectric materials, the large-scale nanofabrication of piezoelectric nanoassembles, and the implications of being able to generate flexible yet highly efficient power sources self-sustaining systems on stretchable, biocompatible substrates. The ribbons will be nanomanufactured from single crystal, stoichiometric films of PZT, allowing for exceptional control over the composition and, consequently, the performance characteristics of these materials. Preliminary data in the form of fundamental characterization of the ribbons by piezo-force microscopy (PFM) indicates that electromechanical energy conversion metrics of the PZT ribbons are among the highest reported on a flexible medium. The excellent performance of the piezo-ribbon nanoassemblies coupled with stretchable, biocompatible rubber may enable a host of exciting applications.
Piezoelectric Nanoribbon Assemblies Printed onto Rubber for Highly Efficent, Flexible Energy Harvesting Michael C. McAlpine, Department of Mechanical and Aerospace Engineering Efficient, highly portable energy sources have attracted increased interest due to the proliferation of handheld consumer electronics. Decreasing power requirements for mobile electronics open the possibility of augmenting batteries with systems that continuously scavenge otherwise wasted energy from the environment. Most intriguing is the possibility of utilizing work produced by the human body via everyday activities, such as breathing or walking. For example, the heel strike during walking is a particularly rich source of energy, with 67 watts of power available from a brisk walker. Harvesting even 1-5% of that power would be sufficient to run many body-worn devices such as mobile phones. Similarly, lung motion by breathing can generate up to 1 W of power. If this power were harvested into charging a pacemaker battery (~5 W), it may increase the time required between battery replacement surgeries for patients. The development of a method for integrating highly efficient energy conversion materials onto stretchable, biocompatible rubbers could yield breakthroughs in implantable or wearable energy harvesting systems. Piezoelectric materials represent a particularly interesting subset of smart materials which function as mechanical to electrical energy converters. Yet, the making these materials generally requires high temperatures for maximally efficient performance, rendering them incompatible with temperature-sensitive plastics and rubbers. Thanks for generous NSF support, we have overcome these limitations by presenting a scalable and parallel process for transferring crystalline piezoelectric ribbons from host substrates onto flexible plastics over macroscopic areas. The approach is analogous to printing newspaper ink onto silly putty. Characterization of the ribbons has shown that electromechanical energy conversion metrics of the PZT ribbons are among the highest reported on a flexible medium. The excellent performance of the piezo-ribbon assemblies coupled with stretchable, biocompatible rubber may enable a host of exciting applications, such as power generation from walking or breathing.
