Wireless Power Technologies for Biomedical Devices

Table of Contents

1. Frontmatter

2. Chapter 1. Wireless Power Transfer for Self-Reporting Cardiovascular Implantable Medical Devices

   Jungang Zhang

   Abstract

   Cardiovascular disease (CVD), a collective of disorders of the heart and blood vessels, is a leading cause of the death and morbidity worldwide. Cardiovascular medical implantable devices (cIMDs) are an effective treatment that can access and restore the functions of the failed or diseased cardiovascular system by surgical implantation. However, the majority of cIMDs such as pacemakers, defibrillators, and ventricular assist devices are intended to remain permanently to maintaining the patients’ life, they are powered by batteries that require frequent replacement before running out of power. This chapter provides a specific review of advanced wireless power transfer (WPT) technique for driving the long-term functionality of cIMDs. WPT holds great promise for eliminating the need for percutaneous wires and enabling long-term powering of medical devices, paving the way for more efficient and convenient healthcare solutions that significantly reduce the risk of side effects associated with battery replacements.

3. Chapter 2. Advancements in Energy Harvesting for Implantable Cardiovascular Devices

   Bhavani Prasad Yalagala, Jungang Zhang, Rupam Das, Hadi Heidari

   Abstract

   This chapter provides a comprehensive overview of energy harvesting solutions for self-powering cardiovascular implantable medical devices. It explores different types of energy harvesters, including Triboelectric Nanogenerators (TENG), Piezoelectric Nanogenerators (PENG), Thermoelectric Generators (TEG), and Biofuel cells, along with novel materials, fabrication strategies, challenges, design aspects, and applications. The chapter delves into the unique operating principles of each energy harvester, elucidating how TENGs convert mechanical energy through the triboelectric effect, PENGs harness mechanical energy through piezoelectric materials, TEGs enable energy conversion from temperature gradients, and Biofuel cells utilize biological reactions for energy generation. It highlights the significance of materials selection, including flexible polymers, nanomaterials, and hybrid composites, to enhance device performance and biocompatibility. Fabrication strategies such as 3D printing, thin-film deposition, and microfabrication are explored in depth, emphasizing their role in producing complex and miniaturized energy harvesting devices. The chapter addresses challenges, including power optimization, miniaturization, reliability, and long-term stability. It also discusses design considerations like power management circuits and integration with existing medical devices to ensure efficient energy conversion and seamless implant integration. The applications of energy harvesting solutions in cardiovascular implants are highlighted, encompassing pacemakers, defibrillators, biosensors, and monitoring devices. The chapter emphasizes the potential for self-powered implants to reduce battery replacement surgeries, enhancing patient convenience and reducing healthcare costs.

4. Chapter 3. Magnetoelectric Composites for Implantable Wireless Power Transfer in Biomedical Applications

   Eve McGlynn

   Abstract

   The magnetoelectric effect is a reversible coupling between a piezoelectric phase and a magnetostrictive phase, meaning, a changing magnetic field may be used to generate a potential difference or vice versa. Formally, this is more accurately described as a change in polarisation with a change in the magnetic field. While this effect has been observed in selected materials, it is more commonly seen in composites which combine a piezoelectric material with a magnetostrictive one, with coupling occurring at the interface. Over the past decades, research in this area has come in and out of fashion with the advent of new materials, geometries and fabrication processes, each of which bring magnetoelectric devices closer to the point of usefulness (Fig. 3.1).

5. Chapter 4. Triboelectric Nanogenerators Competency to Wireless Device Applications

   P. Ravi Sankar, P. Supraja, K. Prakash, R. Rakesh Kumar, K. Uday Kumar

   Abstract

   The most significant way to tackle the energy issue is to convert energy from daily activities into usable electrical energy. The use of batteries, which have a difficult time being recycled and disposed of, does not endorse this idea. There aren’t many energy harvesters for electrical vibration energy harvesting; their manufacture, installation, and maintenance are challenging. Triboelectric nanogenerators (TENG) can act as an alternate energy source in place of batteries for low-power portable electronic devices. TENGs have advantages such as accessible design, low cost of production, and excellent energy efficiency. TENGs can function in various modes, including contact separation, sliding, single electrode, and free-standing modes. The structure of TENGs and their corresponding operating modes can be used for generating electricity, wearable power sources, and sensors. This chapter is focused on an overview of the literature, the basic principles of TENG, manufacturing of TENGs through various working modes, and finally, applications of TENG in self-powered portable and wearable devices and wireless power transmission.

6. Chapter 5. Photovoltaic Energy Scavenging for the Sustainable Implantable Medical Device

   Jinwei Zhao

   Abstract

   Wireless implantable technologies are becoming more common in biomedical applications such as physical identification, real-time health monitoring, and physiological trait recording. Current implantable devices, which frequently require surgical replacement, are powered by batteries. Self-powered implanted devices are appealing in this sense for real-time monitoring of human physiological features. Furthermore, electricity collection and generation beneath human tissue remains a serious hurdle. Nonetheless, as packaging and nanotechnology improve, alternate harvesting approaches based on piezoelectricity, thermoelectricity, biofuel, and radio frequency power transfer are emerging. All of these approaches have constraints such as limited power output, bulky size, or low efficiency. Photovoltaic (PV) energy conversion is one of the most promising candidates for implantable applications due to their higher-power conversion efficiencies and small size. Because of its greater conversion efficiencies and small size, photovoltaic (PV) energy conversion is one of the most attractive possibilities for implantable applications.

7. Chapter 6. Ultrasound-Based Wireless Powering Technologies

   Milad Zamani, Seyedsina Hosseini, Kjeld Laursen, Amin Rashidi, Saeed Baghaee Ivriq, Yasser Rezaeiyan, Farshad Moradi

   Abstract

   For many biomedical applications, acoustic power transfer is superior to other methods for powering. This chapter is devoted to ultrasonically powered devices, the concept, and the hardware necessary to make them work. A detailed description of acoustic powering and the physics of acoustic is provided to enable a full understanding of this technology. Acoustic powering and piezoelectrics as crystalline electromechanical materials are explained in the first section. Their characteristics, materials, and modeling will also be discussed. In addition, ultrasound transducers are discussed in terms of their different designs. Then, the design of the external device transmitter will be presented as a driver to transmit the power to the biomedical implantable device. Next, we present an example of an implanted brain device used for optogenetics in order to illustrate the most important blocks for harvesting the ultrasound power from the external device.

8. Chapter 7. Smart Contact Lens

   Mengyao Yuan

   Abstract

   Electronic wearable devices have gained significant traction and popularity in recent years. Wearable devices are designed to possess data processing for health and fitness [1–3]; biometric tracking, temperature regulation, and posture correction such as smart clothing; immersive experiences of the human-machine interface through Augmented Reality (AR) and Virtual Reality (VR); personal safety and security of emergency assistance or location tracking; and medical and assistive devices such as wearable Electrocardiogram (ECG) monitors, smart prosthetics, and smart contact lens. The emergence of smart contact lenses represents a remarkable advancement in wearable technology, offering numerous potential benefits and transforming the way we interact with the world. These innovative devices, worn directly on the eye, integrate cutting-edge electronics, sensors, and wireless communication capabilities to provide a range of functionalities beyond traditional vision correction. In the future, smart contact lenses are expected to revolutionize various aspects of our lives. They hold immense potential in the fields of healthcare, augmented reality, and personalized computing. One of the key drivers for their development is the need for non-intrusive, unobtrusive health monitoring. Smart contact lenses have the potential to continuously and non-invasively monitor vital signs and biomarkers, enabling early detection of diseases and providing real-time health insights.

9. Chapter 8. Next-Generation SIMO Converter: A Step Beyond SISOs with Novel Approach

   Kaung Oo Htet

   Abstract

   Nowadays, biomedical devices with integrated microelectronics are incorporated into modern healthcare systems. Advances in CMOS fabrication processes are further miniaturising these devices. These devices will be integrated on Implantable neural probes [1], pacemakers [1, 2]and many more. Thus, enhancing the quality of day-to-day healthcare. Such devices can be divided into several building blocks, see Fig. 8.1, such as sensors [3, 4], ADC [5], MEM devices [6], memory [7] and so on. These components are implemented to serve the purpose of recording, stimulation, and communication. Each of these not only has different functionalities also require different operating voltages and load currents powered by a battery or energy harvester through DC-DC converters. These converters are based on the charge pump designs. In search of reliable and efficient charge pump converter quality can be examined by performance and reliability, depicted in Fig. 8.2. Performance of the converter is defined by the power efficiency and voltage conversion ratio. On the other hand, reliability is defined upon converter’s ability to handle variation in output side (Load Regulation) and input side (Line Regulation).

10. Chapter 9. Power Management Integrated Circuits for Implantable Devices

    Chuang Wang

    Abstract

    Implantable devices are inserted into the human body for various purposes such as monitoring diverse health conditions and/or assisting physical activities [1, 2]. For implantable devices, the physical volume and energy efficiency are two important factors. First, the physical volume is directly proportional to the burden placed on the human body. Therefore, any additional external passive components should be eliminated in the design of an implantable device. Second, because the implantable devices operate in energy-limited environments, the given energy must be optimally used to minimize power loss. For now, a few types of energy sources, such as batteries, harvested energies, or a combination of them [3–5] are used to power the implantable devices. Though various harvested energies are promising in the future, the batteries are currently reliable and effective. A cion or Li-ion battery voltage of 1.5–5 V usually provides the energy and acts as the energy source. The implantable device is typically powered by sub-1 V supply rail to improve the energy efficiency and prolong its life [6]. Thus, a step-down DC-DC converter with a relatively low voltage conversion ratio (VCR) is highly desirable to act as the power supply of the implantable device, as shown in Fig. 9.1.