## 3 Smart Implants Development Challenges  
Despite current progress in implantable bioelectronics such as electrocouticals, many challenges must be addressed to provide safe, precise, and targeted therapy. Many implanted bioelectronic devices are wired with battery-powered and bulky, which are invasive, causing discomfort to the patient and limiting their usage. As an alternative, [PERSON] et al. succeeded in developing a wireless implantable bioelectronic device that can compete with traditional ones [35]. However, these kinds of devices also exhibit some challenges. Among them, the challenges that must be addressed are relevant to efficiency, biocompatibility, etc., [36; 37; 38]. How do these devices efficiently transfer energy inside of the body without any losses? What are the available sources of power? Can these power sources be compatible with the biological body and the communicated device located outside of the body? Do they adapt with the surrounding tissues or biological cells without creating any abnormalities? Can we miniaturize them as small as in nanoscale, or maybe more? Can we combine implanted device technology and nanotechnology so that the miniaturized implantable devices cannot hurt the surrounding biological tissues while efficiently treating the disease? Do they communicate securely with the external device? What sort of electronics components and feedback loops are needed to help the user control the device functionalities? What kind of software is necessary to control them remotely? How do we tackle these challenging questions to provide a better therapy is gaining attention? More recently, these challenges are gaining attention concerning pacemaker, neural stimulation, artificial retina, and vagus nerve stimulation-based device development, which is attributable to the importance of these implantable biomedical machines crucial for thinking, acting, and living well. Designing an implantable wireless electroetical device with its receiver antennae or an inductive coil-based receiver system is still bulky due to its limitation in miniaturization capability-enabled functionality. To operate an electroetical device, a few to several hundred microwatts of energy is required. The optimized design (length, height, and width while maintaining material functional parameters) is needed to deliver enough power to handle designated therapeutic operations. Thus, a considerable challenge must be addressed when miniaturizing the wireless power transfer system [37; 38; 39]. This challenge can be overcome with the help of advanced materials, nanotechnologies-enabled functional components, and electromagnetic simulation tools that optimize designs. Though current technologies are capable of triggering activities of respective tissues, miniaturized electroetical devices capable of both monitoring and treating functionality integrated into a single device are of industrialists' and biomedical engineers' current interest [35; 40; 41]. There is significant interest in developing wireless devices that could monitor, record, and treat neural activity. For example, for better vision, the artificial retina system could stimulate the retinal neurons by measuring their abnormal activity [35; 41; 42]. Similarly, a pacemaker system could deliver impulsive responses by understanding the abnormal activity of the heart through the implantable electrocardiograph monitoring device [35; 41; 42]. Although the micro/nanoscale technologies could help in miniaturizing wireless power transfer receivers as a part of an intelligent system, developing multi-functional advantages in an integrated electronic chip by considering all relevant factors may be a challenging task. A great challenge is developing an integrated system with sophisticated electronic circuits that could help interface, interact, communicate with the outer environment and the systems, and perform multiple tasks.