M. De Cooman

A multi-purpose CMOS sensor interface for low-power applications

A dedicated low power CMOS tranponder microchip is presented as part of a novel telemetry implant for biomedical applications. This mixed analog-digital circuit contains an identification code and collects information on physiological parameters, i.e. body temperature and physical activity. Emphasis is on a high degree of flexibility towards sensor inputs and internal data management, extreme miniaturization and low power consumption to allow implantation.

A low power multi-sensor interface for injectable microprocessor-based animal monitoring system

Abstract In the research field of several biomedical disciplines a major need exists for reliable and implantable telemetry sensor systems. Apart from the demands for small size, light weight and long operational lifetime, the sensor systems should preferably also be flexible, versatile and intelligent. As a follow-up of previous work, a novel and more powerful transponder is developed, specifically tailored for applications in large-scale animal husbandry. It is a read—write telemetry device based on a microprocessor configuration, containing a dedicated sensor interface chip (SIC), SMD thermistor and subminiature capacitive accelerometers.

A low power miniaturized autonomous data logger for dental implants

This paper presents a low power miniaturized, autonomous data logger, capable of measuring, compensating and processing 18 different strain gauges simultaneously. The total system, which is part of a dental prosthesis, consists of a multi-channel strain gauge interface, a bi-directional rf link, a 2 MB RAM and a digital data processing/controlling unit. The sensor interface has been implemented in a 0.7 μm CMOS technology and includes a proportional to absolute temperature current reference, an 8-bit digital-to-analog converter (DAC) for compensation, a switched-capacitor instrumentation amplifier, a switched-capacitor sample-and-hold and a 9-bit successive approximation analog-to-digital converter (ADC). This interface chip consumes a mere 40 μA per channel, allowing functionality of the data logger for a 2-day period in the highest sampling mode, i.e. continuous sampling of six abutments with three strain gauges at a 111 Hz sampling rate per channel with a 20 μstrain accuracy.

A low power multi-channel sensor interface for use in digital telemetry

Abstract A novel telemetry transponder is presented for application in an extensive animal monitoring and climatic control system. It contains an identification code and collects information on physiological parameters related to health and welfare of the individual animal. A dedicated low power CMOS transponder microchip is developed. Emphasis is on a high degree of flexibility towards sensor inputs and internal data management, and extreme miniaturization and low power consumption to allow implantation.

A composite membrane movement detector with dedicated interface electronics for animal activity tracking

Abstract For the in vivo measurement of the state of motion of animals, a subminiature capacitive movement detector with dedicated analogue interface circuit and digital postprocessing is developed. A switched capacitor circuit converts the variable capacitance of the movement detector into a voltage, linearly dependent on the acceleration. Postprocessing is necessary to obtain an efficient telemetry system in terms of power consumption and transmission time. The micromachined movement detector has an overall size of 1 mm3. Design concept and fabrication procedure are elaborated with emphasis on the most critical stages.

Injectable biotelemetry CMOS chip for identification and temperature measurement system

Drug combinations often yield results not readily predictable from those of their separate constituents. Computer programs have been developed to generate models of dual drug effects to analyse the results of experiments involving drug combinations. Single and combined dose-response results of rat locomotor activity are expressed as three-dimensional models. A manually plotted isobol diagram, showing eqi-active dose combinations of amylobarbitone and dexamphetamine, is compared with isobols constructed by the computer. A simple dose model theory is proposed which assumes that the two drugs have merely additive effects; differences between expectations from this theoretical model and the experimental results actually obtained were found by the computer. This computer approach allows detailed analysis of results. Three-dimensional dose response surfaces can provide a simple visual guide to dose combinations whose effects deviate significantly from those expected if the constituents were simply additive. Areas of special interest can thus be highlighted.

Towards the limits in detecting low-level strain with multiple piezo-resistive sensors

Strain gauges are widely accepted to quantify load figures in many applications. Their noise immunity is a major factor for their success. In the present work, the limits are explored up to where these strain gauges can be operated in minimal power conditions, and yet allowing strain levels as low as 10 μstrain. A system is proposed which is capable of monitoring 18 gauges simultaneously and continuously with an overall mean current consumption of about 670 μA (at 3.1 V). The final goal is to monitor stress in dental implants, using a miniaturised battery (40 mA h), built into the prosthesis itself. This paper is a first report on work in progress.

Design and integration of a remotely programmable dental monitoring device

In attempts to improve the quality of life (QOL), continuously methods are sought that make use of the symbiosis between medicine and technology. The knowledge of biomedical processes opens the way to a technically controlled rehabilitation. One such approach uses the knowledge on bone remodeling and bone growth in a dental environment. By applying immediate load on a newly placed implant, the bone growth is positively stimulated. However, excessive loading should be avoided at all times. Therefore a complete device was designed that is able to monitor the implant loading and gives patient feedback when overloading occurs. To the authors knowledge, it is the first time such a system is proposed. In this paper, the design of the smart dental prosthesis is elaborated

An autonomous smart dental prosthesis for fast rehabilitation

The continuous miniaturization of electronics and increasing knowledge of biological processes enable us to develop intelligent implantable systems to enhance the quality of life. One of such systems controls the passive stimulation of bone formation in a dental environment. By giving patient feedback in case of overload, one should be able to minimize rehabilitation period drastically. We developed an electronic dental prosthesis, incorporating an ASIC (application specific IC), power supply system and necessary sensors. The electronic components are incorporated into a custom designed dental framework. The system can communicate wirelessly with an external transceiver which enables a patient tailored approach. In situ calibration and threshold programming is performed before the dental prosthesis works as a completely autonomous device

A Double Sided Capacitive Miniaturised Accelerometer Based On Photovoltaic Etch Stop Technique

A double sided capacitive miniaturised accelerometer is presented. The photovoltaic etch stop technique, PHET [ 11, is used to simplify the device fabrication. P E T being a relatively new technique, the paper emphasises on the design rules required in order to have an etch stop. The device is an uniaxial accelerometer with practically no cross sensitivity, which can sense accelerations in the range of -5 to 5 g. The parasitic capacitances and the effects of the electric forces driving the device are cancelled out by its symmetry. The final device measures 2.2 . 2.0. 1.5 mm3.