Recent Advances on Hybrid Piezo-Triboelectric Bio-Nanogenerators: Materials, Architectures and Circuitry

Abstract

Nanogenerators, based on piezoelectric or triboelectric materials, have emerged in the recent years as an attractive cost-effective technology for harvesting energy from renewable and clean energy sources, but also for human sensing and biomedical wearable/implantable applications. Advances in materials engineering have enlightened new opportunities for the creation and use of novel biocompatible soft materials as well as micro/nano-structured or chemically-functionalized interfaces. Hybridization is a key concept that can be used to enhance the performances of the single devices, by coupling more transducing mechanisms in a single-integrated micro-system. It has attracted plenty of research interest due to the promising effects of signal enhancement and simultaneous adaptability to different operating conditions. This review covers and classifies the main types of hybridization of piezo-triboelectric bio-nanogenerators and it also provides an overview of the most recent advances in terms of material synthesis, engineering applications, power-management circuits and technical issues for the development of reliable implantable devices. State-of-the-art applications in the fields of energy harvesting, in vitro/in vivo biomedical sensing, implantable bioelectronics are outlined and presented. The applicative perspectives and challenges are finally discussed, with the aim to suggest improvements in the design and implementation of next-generation hybrid bio-nanogenerators and biosensors.

Applications of Triboelectric Nanogenerators in Bone Tissue Engineering

“…Based on the unique features of TENGs, they can be universally accepted as personalized healthcare devices implanted into the human body, embedded with skin or clothes, with minimal harmful effects and discomfort. [ 80 ] Generally, the research mentioned above has shown the importance of TENGs, and laid the foundation for further investigation in bone tissue engineering and other biomedical sectors. [ 4 ] Despite the substantial impact TENGs have made, the applications of TENGs are still in their infant stage, especially for bone tissue engineering.…”

Natural Piezoelectric Biomaterials: A Biocompatible and Sustainable Building Block for Biomedical Devices

“…Based on the device geometry, we suspect that some of the measurements may also include other surface charge contributions. Although hybrid NGs incorporating both piezoelectric and triboelectric effects have been reported as a successful strategy to improve the overall output, 163 it is still essential to identify the contributions from different mechanisms to establish a reliable materials property relationship.…”

Carbon Nanotube-Assisted Device Performance Improvement in Flexible Piezoceramic–Polymer Hybrid Nanogenerators

“…Depleting fossil fuels and the environmental impact of burning fossil fuels have spurred a quest for nonconventional green energy sources. , Harvesting electrical energy from ambient mechanical energy is one of the popular approaches and can be utilized to power low-wattage electronic devices. − Triboelectricity, which has existed in nature for over 2600 years, originates from contact electrification, in a metal–dielectric system predominantly due to the electron transfer mechanism. , The discovery of a triboelectric nanogenerator (TENG) in 2012 has led to widespread research activities to improve the output device performance using various complementary mechanisms such as piezoelectricity, pyroelectricity, and different media. − Despite a high output voltage, TENG devices suffer from wear and tear and pose a challenge in long-term uses. − A piezoelectric nanogenerator (PENG) can generate a stable and high electrical output; however, it lacks flexibility. , Hybrid nanogenerators (HNGs) combine triboelectric and piezoelectric effects and can offer stable and high output voltages as well as flexibility. , HNGs have potential applications in the next-generation self-powered sensing devices, especially in the field of health monitoring due to their added flexibility. − A conventional approach to forming HNGs combines the effects in a triboelectric polymer–piezoceramic composite matrix that acts as an active layer to produce the desired electrical output. , Among the various triboelectric materials/polymers, poly­(dimethylsiloxane) (PDMS) , offers suitable elastic properties (elastic modulus of 1.32–2.97 MPa), low cost, and flexibility and it is advantageous due to better electron acceptor properties with respect to metal electrodes. , …”