Implant power

How is an implant powered?

Strategic Research Agenda Of The European Technology Platform On Smart Systems Integration

The battery characteristics of a medical implant permanently monitoring physiological parameters is very different from the energy source of a wireless sensor which spends 99% of its time in idle mode and which is woken up once or twice a day to make a temperature or acceleration measurement.

the progress of silicon technologies over the last ten years is leading to a whole family of autonomous devices displaying average power consumption in the 10μW to the 1 mW range.

http://www.smart-systems-integration.org/public/documents/070306_EPoSS_SRA_v1.02.pdf

The device is powered by a battery that is recharged when the user places a small radio transmitter against his or her head for 60 to 90 minutes. The transmitter is held to the skin by a magnet in the implant. An inductive coil in the implant converts the radio energy to electricity and recharges the battery with it. The battery can stay inside the body for at least five years, according to the company, before it needs to be replaced.

http://callierlibrary.wordpress.com/category/hearing-aids/

Inductively-Coupled Control Unit for Fully Implantable Middle Ear Hearing Devices

Summary:Recently, fully-implantable middle ear hearing devices (F-IMEHD) to enhance the hearing ability of auditory impaired persons have been developed in several countries. The implantable hearing device requires an external controller and a non-invasive power transmitter for recharging an internal battery of the device. This study shows the implementation of an inductively coupled control unit to be able to recharge the battery and transmit a control signal to the implanted device by designing the structure of coupled antennas and the data protocol using an on-off keying modulation. The implemented control unit has the advantages that it makes the implanted device reduce the power consumption and increase a recharging interval by externally supplying the power of a control signal receiver instead of using an internal battery. Through the experimental results, it has been verified that the implemented control unit has the performance of transmitting power and control signal to a F-IMEHD

http://ieeexplore.ieee.org/Xplore/login.jsp?url=/iel5/10755/33900/01615521.pdf

Preliminary Assessment of Remote Photoelectric Excitation of an Actuator for a Hearing Implant

Summary:Sound modulated infrared (IR) light, as an alternative signal (and energy) transmission method, was evaluated for remote powering of a hearing implant via an implanted photodiode receiver. One human cadaveric temporal bone was used to test this concept by locating an IR source (LED) in the ear canal 4 mm away from the eardrum and a photodiode in the middle ear cavity. The photodiode output was directly used to drive a piezo-ceramic disc actuator which was located externally for facilitating the test. The displacement frequency response of the actuator was measured by a laser vibrometer. It was found that, at a LED current of 8.6 mA, the actuator displacement was about 22.4 nm, equivalent to a stapes displacement from about 91 dB sound-pressure-level (SPL) stimulation at the eardrum. The IR light transmittance through the eardrum (compared to through an air path) was about 67%. The LED optical power was 0.77 mW (its maximal irradiance was about 3.95 mW/cm2) which is a safe to the human body. Current consumption can be reduced by a factor of 3-5 by using a more efficient LED and photodiode

http://ieeexplore.ieee.org/Xplore/login.jsp?url=/iel5/10755/33900/01615920.pdf

photoreceiver of the ear implant and converted to an electrical signal for driving the hearing actuator

http://www.wipo.int/pctdb/en/wo.jsp?wo=2003063542&IA=WO2003063542&DISPLAY=DESC

Power Harvesting For Implanted Devices

The traditional approach of using wires leaves the patient open to infection and has many other drawbacks. To eliminate these obstacles, our group has started work on a VLSI chip that uses inductive coupling to transfer both power and data. A picture of the layout of the chip is show at the left. For reference, the chip is called the SIC Chip (Sensor Interface and Conditioning). A 4 MHz carrier wave is used to convey energy through the skin to reach the implanted device. The energy is recovered and converted into a steady DC voltage for sensor use. A novel voltage reference circuit allows the entire design to be fabricated in commercial CMOS technology.

http://www.jhu.edu/nthakor/people_pages/chris/main.htm

Development of Ultrasonic Energy Transmission System for Implanted Device.

A power transmission system using ultrasound for implantable devices is proposed in this paper. Ultrasonic power transmission is especially suited for mobile devices inside the human body such as gastrointestinal measuring capsules because of the remote measuring ability. In this study, the authors define the basic characteristics of the system. It is shown that the proposed system is described by the equivalent piezoelectric transformer circuit and evaluated using rf power transmission experiments used for telemetry systems.

http://sciencelinks.jp/j-east/article/200205/000020020502A0063258.php

Transcutaneous Electrical Nerve Stimulator.

There are a number of manufacturers of these units and several different types. They have a similarity in that they generally use a 9-volt radio battery to produce a small electric current. They differ in how the electric current is delivered and what is called the wave form of the electric current.

http://www.headaches.org/consumer/topicsheets/tens.html