Bojing Shi

In Vivo Powering of Pacemaker by Breathing‐Driven Implanted Triboelectric Nanogenerator

The first application of an implanted triboelectric nanogenerator (iTENG) that enables harvesting energy from in vivo mechanical movement in breathing to directly drive a pacemaker is reported. The energy harvested by iTENG from animal breathing is stored in a capacitor and successfully drives a pacemaker prototype to regulate the heart rate of a rat. This research shows a feasible approach to scavenge biomechanical energy, and presents a crucial step forward for lifetime-implantable self-powered medical devices.

Biodegradable triboelectric nanogenerator as a life-time designed implantable power source

Mechanical energy in vivo could be harvested by BD-TENG in a designed time frame. Transient electronics built with degradable organic and inorganic materials is an emerging area and has shown great potential for in vivo sensors and therapeutic devices. However, most of these devices require external power sources to function, which may limit their applications for in vivo cases. We report a biodegradable triboelectric nanogenerator (BD-TENG) for in vivo biomechanical energy harvesting, which can be degraded and resorbed in an animal body after completing its work cycle without any adverse long-term effects. Tunable electrical output capabilities and degradation features were achieved by fabricated BD-TENG using different materials. When applying BD-TENG to power two complementary micrograting electrodes, a DC-pulsed electrical field was generated, and the nerve cell growth was successfully orientated, showing its feasibility for neuron-repairing process. Our work demonstrates the potential of BD-TENG as a power source for transient medical devices.

In Vivo Self-Powered Wireless Cardiac Monitoring via Implantable Triboelectric Nanogenerator

Harvesting biomechanical energy in vivo is an important route in obtaining sustainable electric energy for powering implantable medical devices. Here, we demonstrate an innovative implantable triboelectric nanogenerator (iTENG) for in vivo biomechanical energy harvesting. Driven by the heartbeat of adult swine, the output voltage and the corresponding current were improved by factors of 3.5 and 25, respectively, compared with the reported in vivo output performance of biomechanical energy conversion devices. In addition, the in vivo evaluation of the iTENG was demonstrated for over 72 h of implantation, during which the iTENG generated electricity continuously in the active animal. Due to its excellent in vivo performance, a self-powered wireless transmission system was fabricated for real-time wireless cardiac monitoring. Given its outstanding in vivo output and stability, iTENG can be applied not only to power implantable medical devices but also possibly to fabricate a self-powered, wireless healthcare monitoring system.

A Packaged Self‐Powered System with Universal Connectors Based on Hybridized Nanogenerators

A packaged self-powered system by hybridizing nanogenerators (PSNGS) is demonstrated. The performance of the PSNGS is tested in a biofluid and used for powering an electronic thermometer. Select waterproof universal connectors are designed and fabricated for energy and signal transmission. This PSNGS and the connectors can significantly advance the development of self-powered implanted medical devices and wearable/portable electronics.

Recent Progress on Piezoelectric and Triboelectric Energy Harvesters in Biomedical Systems

Implantable medical devices (IMDs) have become indispensable medical tools for improving the quality of life and prolonging the patients lifespan. The minimization and extension of lifetime are main challenges for the development of IMDs. Current innovative research on this topic is focused on internal charging using the energy generated by the physiological environment or natural body activity. To harvest biomechanical energy efficiently, piezoelectric and triboelectric energy harvesters with sophisticated structural and material design have been developed. Energy from body movement, muscle contraction/relaxation, cardiac/lung motions, and blood circulation is captured and used for powering medical devices. Other recent progress in this field includes using PENGs and TENGs for our cognition of the biological processes by biological pressure/strain sensing, or direct intervention of them for some special self‐powered treatments. Future opportunities lie in the fabrication of intelligent, flexible, stretchable, and/or fully biodegradable self‐powered medical systems for monitoring biological signals and treatment of various diseases in vitro and in vivo.

Self‐Powered Pulse Sensor for Antidiastole of Cardiovascular Disease

Cardiovascular diseases are the leading cause of death globally; fortunately, 90% of cardiovascular diseases are preventable by long-term monitoring of physiological signals. Stable, ultralow power consumption, and high-sensitivity sensors are significant for miniaturized wearable physiological signal monitoring systems. Here, this study proposes a flexible self-powered ultrasensitive pulse sensor (SUPS) based on triboelectric active sensor with excellent output performance (1.52 V), high peak signal-noise ratio (45 dB), long-term performance (107 cycles), and low cost price. Attributed to the crucial features of acquiring easy-processed pulse waveform, which is consistent with second derivative of signal from conventional pulse sensor, SUPS can be integrated with a bluetooth chip to provide accurate, wireless, and real-time monitoring of pulse signals of cardiovascular system on a smart phone/PC. Antidiastole of coronary heart disease, atrial septal defect, and atrial fibrillation are made, and the arrhythmia (atrial fibrillation) is indicative diagnosed from health, by characteristic exponent analysis of pulse signals accessed from volunteer patients. This SUPS is expected to be applied in self-powered, wearable intelligent mobile diagnosis of cardiovascular disease in the future.

Robust Multilayered Encapsulation for High-Performance Triboelectric Nanogenerator in Harsh Environment

Harvesting biomechanical energy especially in vivo is of special significance for sustainable powering of wearable/implantable electronics. The triboelectric nanogenerator (TENG) is one of the most promising solutions considering its high efficiency, low cost, light weight, and easy fabrication, but its performance will be greatly affected if there is moisture or liquid leaked into the device when applied in vivo. Here, we demonstrate a multiple encapsulation process of the TENG to maintain its output performance in various harsh environments. Through systematic studies, the encapsulated TENG showed great reliability in humid or even harsh environment over 30 days with a stability index of more than 95%. Given its outstanding reliability, the TENG has the potential to be applied in variety of circumstances to function as a sustainable power source for self-powered biomedical electronics and environmental sensing systems.

Implantable Energy-Harvesting Devices

The sustainable operation of implanted medical devices is essential for healthcare applications. However, limited battery capacity is a key challenge for most implantable medical electronics (IMEs). The human body abounds with mechanical and chemical energy, such as the heartbeat, breathing, blood circulation, and the oxidation-reduction of glucose. Harvesting energy from the human body is a possible approach for powering IMEs. Many new methods for developing in vivo energy harvesters (IVEHs) have been proposed for powering IMEs. In this context energy harvesters based on the piezoelectric effect, triboelectric effect, automatic wristwatch devices, biofuel cells, endocochlear potential, and light, with an emphasis on fabrication, energy output, power management, durability, animal experiments, evaluation criteria, and typical applications are discussed. Importantly, the IVEHs that are discussed, are actually implanted into living things. Future challenges and perspectives are also highlighted.