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Biomedical subjects

W H Ko

Publications and source records attributed to W H Ko.

At least 73 records · Page 4Linked to original sources
PubMed1983

A review of implantable sensors.

Solid state sensors offer high performance, small size, lower cost, and compatibility with computing circuits. The current status of these sensors for biomedical applications is reviewed. Physical transducers may be used to measure pressure, flow, acceleration, velocity, etc. Chemical transducers may measure H+, K+, Na+, etc. Research required for their implantation is suggested.

Animals↗
PubMed1981

Intracranial pressure telemetry system. I. Hardware development.

Results in the development of intracranial pressure(ICP) telemetry systems are reported. Included are a single-channel ICP system and a two-channel ICP and temperature system. The unit used hybrid-integrated circuits housed in a Kovar flatpack and packaged with polyurethane or Hysol epoxy. Battery and radio frequency (RF) induction power supplies were tested. The two-channel systems used RF power at 3.5 MHz and transmitted signals around 120 MHz. The package measures 3 x 2 x 0.8 cm and weighs 9 g. The pressure range is -20 to +100 mm Hg with accuracy to 1.0 mm Hg. The implant measures absolute pressure and has a baseline stability of better than +/- 2 mm Hg/month. 17 dogs and 4 goats were used for in vivo evaluation. A summary of results is presented. Detailed evaluation is given in section II of this paper.

Animals↗
PubMed1981

Intracranial pressure telemetry system. II. Animal testing.

A small, implantable, telemetric device for the long-term monitoring of intracranial pressure has been described in part I of this article. This portion of the study is designed to demonstrate the in vivo operational characteristics of that implant device in experimental animals. Results indicate that this system can provide long-term in vivo operation with rapid and accurate responses to acute changes in pressure. Data also indicate some drift in the baseline measurement of pressure. No signs of abnormal body reactions to the units were observed.

Animals↗
PubMed1981

An implantable micropower command receiver for telemetry battery power switching.

Command receivers that control the functioning of additional implanted circuitry can be useful in many medical telemetry applications. The authors have designed and constructed a thick-film hybrid command receiver system that directly interfaces with the second-generation ICP telemetry system. This command receiver controls telemetry on/off state through enabling/disabling the telemetry pulse generator stage. Lithium battery powering of the implant is made practical through use of this command receiver. An automatic power shutdown feature is incorporated to guard against accidental battery drain. The unit uses two commercial CMOS integrated circuits, a transistor, a resistor and an RF coil.

Electric Power Supplies↗
PubMed1981

An implantable RF-powered dual channel stimulator.

An implantable RF-powered dual channel stimulator was designed for hip stabilization. The approach included: small size, low power consumption, external powering, adjustable output current stimulus, dual channel operation an hermetic sealed electronic packaging. Thick film hybrid circuit techniques were used. The circuit and RF powering scheme were designed for low power operation with compromise to allow for linear and lateral displacements between the transmitting and receiving antenna. The output stimuli are biphasic negative going current pulses of 175 microseconds duration and 0-5 mA amplitude. Hermeticity is provided by enclosure of the electronics in a flat pack and subsequent epoxy coating of the implant assembly.

Cerebrovascular Disorders↗