Date Published: March 27, 2017
Publisher: John Wiley and Sons Inc.
Author(s): Qiang Zheng, Bojing Shi, Zhou Li, Zhong Lin Wang.
Implantable medical devices (IMDs) have become indispensable medical tools for improving the quality of life and prolonging the patient’s 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.
Over last decades, implantable medical devices (IMDs) have experienced tremendous growth, becoming indispensable medical tools for improving the quality of life and prolonging the patient’s lifespan. Currently, the IMDs have been implanted in various parts of human body as artificial treatments and diagnostic tools, including sensors, pacemakers, implantable cardioverter defibrillators, cochlear implant and stimulators for deep brain, nerve and bone.1 These implantable electronic devices can provide diagnosis (e.g. heart rate, blood pressure and temperature monitoring) for a number of diseases related to the heart, brain and some other important organs and support real‐time treatment (e.g. stimulation of muscle and nerve system). For instance, a cardiac pacemaker can help to correct abnormal heart rhythms by using electrical stimulation to contract the patients’ cardiac muscle to relieve heart blockage or sick sinus syndrome.2 Additionally, to achieve better quality of life and enhance the survival rateof patients worldwide, IMDs have also contributed significantly to our cognition of the biological processes existing in the human body, including the complicated mechanisms of neural communication, memory and control, which significantly deepen our understanding of how these processes are affected by differernt diseases and treatments.3
Biomedical systems and nanotechnologies are revolutionizing healthcare and medicine; their synergy could be extremely powerful, and they could play key roles in near‐term medical technologies. Taking into account the decreasing power consumption of microchips and the increasing efficiency of nanomaterials‐based mechanical energy harvesters such as PENGs and TENGs, which should be possible to power autonomous biomedical systems. Reaching energetic independence from current bulky batteries is a first important step for their development. However, to reach this purpose, the optimization of the output performance and power management of nanogenerators need to be addressed in order to increase the energy conversion rate and efficiency in use. Furthermore, to realize their full potential in the field of healthcare, nanogenerators need to continue to evolve more high flexibility, sensitivity, elasticity, stretchability, durability and biocompatibility, to be fully operational in the human body. Autonomous biomedical systems with self‐powered and active sensing properties will be the future development direction of the medical field. For easily using ex vivo and in vivo, they need to be wearable and implantable. In order to achieve this, they will need to be fully flexible to fit the shape of organs, including skin, closely. Thus, the devices will be more discrete and comfortable for the patients, and will be better adapted to their targeted tissue/organ, which will increase their sensing ability and the amount of energy harvested.