Funded Projects

Wearable mobile electronics, soft robotics, and personal healthcare systems are made possible by flexible electronics and they are getting more common in daily life. Solid-state power sources such as lithium-ion batteries are not compatible with flexible, bending devices due to past fires and explosions. On the other hand, flexible piezoelectric energy harvesters (PEHs) have rapidly gained traction as a promising power source for mobile devices because of their simple structures, mechanical durability/flexibility, and robustness in challenging environments. The major impediment to the widespread use of PEHs is the mismatch between their resonance frequencies and ambient vibrational frequencies, which prevents efficient energy harvesting. Although conventional linear vibrational PEHs generate maximum power at their resonance frequencies (tens of kHz due to their small geometry), typical ambient frequencies are much lower (tens of Hz). The study will develop flexible and dynamic three-dimensional (3-D) PEHs from two-dimensional (2-D), free-standing piezoelectric semiconductors by employing innovative hierarchical geometries and structural stability. The 3-D PEHs will be fabricated by adopting kirigami design principles and layer transfer techniques via micro-transfer printing. The research is based on two central hypotheses: (1) the stability-dictated nonlinear dynamic characteristics can generate much more power than the conventional counterparts can, and 2) multi-level wrinkling and hierarchical geometries can substantially amplify the energy capacity. The proposed study links conventional stability theory to an uncharted area of energy-harvester fabrication using 2-D semiconductors. The completion of this research will have a significant impact on the field of flexible electronics and piezoelectric devices because the proposed mechanism can be adopted for the design of a wide range of devices.