Power Amplifiers for Electronic Bio-Implants

Healthcare systems face continual challenges in meeting their aims to provide quality care to their citizens within tight budgets. Ageing populations in the developed world are perhaps one of the greatest concerns in providing quality healthcare in the future. The median age of citizens in economically developed regions is set to approach 40 years by the year 2050, and reach as high as 55 years in Japan. This trend is likely to lead to strained economies caused by less revenue raised by smaller workforces. Another effect of ageing populations is the need of further care in order to remain healthy. This care varies from frequent check-ups to condition monitoring, compensation for organ malfunction and serious surgical operations. As a result of these trends, healthcare systems will face the task of servicing more people with more serious and expensive health services, all using less available funds. Effort is being focused on running cheaper and more effective healthcare systems and the development of technology to assist in this process is a natural research priority

Wireless Power Technology for Biomedical Implants

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Time Domain Multiplexing for Efficiency Enhanced Piezoelectric Energy Harvesting in MEMS

The conversion efficiency of piezoelectric energy harvesters (EH) have been improved by several approaches including frequency up-conversion (FUC) techniques that trigger the high-frequency (HF) piezoelectric resonators using low-frequency (LF) mechanical inputs. This work proposes a new time-domain multiplexing technique to further improve the harvesting efficiency for random mechanical impacts using commercially available microfabrication processes. The FUC is implemented by a slowly moving shuttle beam, which represents the LF mechanical inputs, that triggers the free ends of piezoelectric cantilever beams. Mechanical impacts by the LF shuttle lead to the cantilever beams vibrating at their higher natural resonance frequencies. In the proposed approach, resonators are exposed to the LF mechanical input at unequal distances, which results in sequential HF vibrations. As a result, the HF electrical outputs fit sequentially within the long period of the LF input. Analytical and experimental comparisons support the increased electrical output using time domain multiplexing.</p

An integrated magnetic programming technique for mechanical microresonators

Mechanical memory devices are needed for harsh environments where electronic components fail to operate. An integrated electro-Thermal technique for local magnetic annealing, which enables post-production programming capabilities for mechanical micro-resonators is presented. It is verified by a prototype with ferromagnetic resonating elements suspended on top of a polysilicon resistive heater. The magnetization (M-H) loop, with and without post-fabrication annealing are measured to prove the validity of technique.</p

An integrated magnetic programming technique for mechanical microresonators

Mechanical memory devices are needed for harsh environments where electronic components fail to operate. An integrated electro-Thermal technique for local magnetic annealing, which enables post-production programming capabilities for mechanical micro-resonators is presented. It is verified by a prototype with ferromagnetic resonating elements suspended on top of a polysilicon resistive heater. The magnetization (M-H) loop, with and without post-fabrication annealing are measured to prove the validity of technique.</p

A Low power MICS band transceiver architecture for implantable devices

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Wearable and implantable wireless body area networks

Using wireless technology for remote patient monitoring has already taken place in hospitals around the world to support diagnostic and therapeutic functions. Although a large number of wireless medical systems have been reported in the literature, they have been designed for specific applications that cover limited number of sensors and patients. Future wireless medical monitoring systems should be used in a wireless body area network (WBAN) scheme in order to operate in a larger area in hospital environments. They should be able to incorporate with other wireless systems such as Bluetooth, WiFi and short-range wireless sensor systems such as ZigBee. Installing an interference free wireless medical network for monitoring physiological parameters in a medical center may be quite challenging since there are a number of other wireless systems or equipments (e.g. Wi-Fi, Bluetooth, ZigBee, Microwave oven) operating already for different purposes. Thus it is very crucial to design an interference free wireless system for a WBAN in medical applications. In addition to unlicensed ISM bands, there are medical bands such as MICS (Medical Implant Communication Service) and WMTS (Wireless Medical Telemetry Service) that are specifically regulated for medical monitoring by communication commissions around the world. The recent short-range low data rate ultra-wideband (UWB) technology is another attractive technology that started to appear for body area network applications due to its low transmitter power. Low power operation is essential for sensor nodes in a wireless body area network application as it determines the life time and the size of the device. It is therefore desirable to use a wireless standard (or a wireless chip) that will provide low power consumption and has a minimum transmitted power that still meets the required range of the body area networks. Recent developments have focused on the designs of individual wireless sensor electronics that can be used as an implantable and wearable node to detect signals such as EEG, ECG, pulse rate and temperature. This work will review the recent advances and relevant patents in wireless body area network applications. Issues related to hardware implementations, software and wireless protocol designs for a complete wireless body area network application have been addressed

Harmonics-based bio-implantable telemetry system

Miniaturization is a key focus for medically implantable electronics such as Cochlear and Retinal prosthesis, and medical monitoring and recording applications. The need for low power dissipation is equally important, and power-hungry crystals and oscillators are commonly used to produce and control the implant's carrier transmission frequency. This paper presents a new harmonics-based method that allows this transmission frequency to be varied and controlled externally, while also minimizing the size and power requirements of certain implanted devices

Low data rate ultra wideband ECG monitoring system

This paper presents a successfully implemented wireless electrocardiograph monitoring using low data rate ultra wideband (UWB) transmission. Low data rate ultra wideband is currently under consideration for the newly formed wireless body area network (WBAN) group (IEEE802.15.6) to develop a standard for wireless vital sign monitoring. Maximizing the transmission power of the transmitter and reducing the stringent requirements and complexity of the receiver have always been the key considerations for an UWB transceiver. Multiple pulses per bit has been sent in our low data rate UWB prototype system to increase the transmitter power, to reduce the complexity of the receiver and to ease the requirement on the receiver's analog to digital converter. Non-coherent technique has been used for the demodulation of UWB signals at the receiver that reduces the receiver complexity further