Researchers from the Korea Advanced Institute of Science and Technology (KAIST) have discovered how to improve the conversion of ambient energy into electrical energy, which can be used for powering wearable and portable devices. The energy harvesting devices, nanogenerators, typically use piezoelectric materials such as zinc oxide to convert mechanical energy to electricity. Uses of such devices include wearables and devices for portable communication, healthcare monitoring, environmental monitoring, and for medical implants. Zinc oxide is particularly suitable for nanogenerator functional elements because it is transparent, lead-free biocompatible, chemical stable, and coupled piezoelectric and semiconductor properties. The nanogenerators are easily fabricated, can be fully integrated with conventional complementary metal-oxide-semiconductor fabrication, and provide greater durability than other types of nanogenerators. The researchers explored ways to vertically integrated zinc oxide nanogenerator energy harvesting chips. They inserted an aluminum-nitride insulating layer into a conventional energy harvesting chip and found that the added layer increased the output voltage a whopping 140 to 200 times. The increase was the result of the high dielectric constant and stiffness.