Innovative Implantable and Wearable Medical Devices Enabled by Ultrasonic Power Transfer and Piezoelectric Energy Harvesting

Open Access
- Author:
- Meng, Miao
- Graduate Program:
- Electrical Engineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- August 05, 2019
- Committee Members:
- Mehdi Kiani, Dissertation Advisor/Co-Advisor
Mehdi Kiani, Committee Chair/Co-Chair
Qiming Zhang, Committee Member
Weihua Guan, Committee Member
Susan E Trolier-Mckinstry, Outside Member
Kultegin Aydin, Program Head/Chair - Keywords:
- Biomedical implants
Design methodology
Ultrasound
Wireless power transmission
Inductive links
Power transfer efficiency (PTE)
Gastric neurophysiology
Power management
Pulse-based data transfer
Piezoelectric energy harvesting
Wearable
Integrated circuit
Slow waves
Beamforming - Abstract:
- The objective of the research work enclosed in this dissertation is to develop high-performance wireless power and data transfer technologies as well as energy harvesting techniques for implantable and wearable medical devices. The first part of the research work focuses on developing wireless power transmission (WPT) to and communication with millimeter (mm)-sized implantable medical devices (IMDs). Ultrasonic and inductive techniques are developed to achieve high power transfer efficiency (PTE) and low-power pulse-based communication. The second part is to implement an ultrasonic wireless link in a real-world application of ultrasonically interrogated distributed system for gastric slow-wave (SW) recording. The third part is to develop a power management integrated circuit (PMIC) for piezoelectric energy harvesting in next generation self-powered wearables. Wireless power and data transmission techniques have been proven to be promising solutions for IMDs considering size, weight and lifetime limitations, such as bioelectronic medicines, biosensors, and neural recording/stimulation systems. Ultrasonic links utilizing piezoelectric transducers have shown advantages over other techniques in miniaturizing the IMDs which can greatly reduce the invasiveness and increase the longevity of the IMDs while maintaining high efficiency, especially for applications requiring deep implantation. Ultrasonic wireless links can be used in many applications. In this dissertation, an ultrasonically interrogated (power/data) distributed system (Gastric Seed) is proposed for large-scale gastric SW recording. Efficient ultrasonic power links and low-power pulse-based data communication are developed. A Gastric Seed chip is developed with emphasis on self-regulated power management and addressable pulse-based data communication. The self-regulated power management can perform rectification, regulation, and over-voltage protection in one step using only one off-chip capacitor which significantly reduces the size of the Gastric Seeds. The addressable pulse-based data communication is proposed and implemented as a proof-of-concept distributed Gastric Seeds. The pulse-based data communication consumes ultra-low power of 440 pJ/bit. Energy harvesting has become more attractive for self-powered wearables that can enable vigilant health monitoring with 24/7 operation. Piezoelectric energy harvesters (PEHs) can be excited by mechanical vibrations to convert mechanical energy into usable electrical power. PEH is in favor because of high power density and scalability. This outlines the need for an efficient energy-harvesting PMIC to extract maximum energy from PEHs that can be used for self-powered wearables. This dissertation summarizes the contributions in research areas of ultrasonic power and data communication links and energy harvesting PMIC for PEHs. The contributions include 1) development of the theory and proposing the design methodology to optimize the PTE of ultrasonic links involving mm-sized receivers (Rx), 2) design, development, and validation of a hybrid inductive-ultrasonic WPT link for powering mm-sized implants utilizing two cascaded co-optimized inductive and ultrasonic links for WPT through media involving air/bone and tissue, 3) proposing the concept of self-image-guided ultrasonic (SIG-US) interrogation in a distributed, addressable peripheral nerve recording system to ensure high delivered power regardless of the implant’s movements by automatically tracking the location of the implant in real time, 4) development of a mm-sized Gastric Seed chip towards a distributed recording system for acquiring gastric SWs at a large scale, and 5) development of an autonomous multi-input reconfigurable power-management chip for optimal energy harvesting from weak multi-axial human motion using a multi-beam PEH.