Bart Hermans

Biomedical Stretchable Sytems using MID Based Stretchable Electronics Technology

In order to fit human body, flexibility, or even better stretchability is requested for biomedical systems like implants or smart clothes. A stretchable electronic technology has been developed. This can provide highly stretchable interconnections fully compatible with PCB technologies. In order to prove the feasibility of complex biomedical systems like inner body implants or wearable systems, a variety of stretchable systems has been designed from sensor to power source systems.

WIRELESS INDUCTIVE TRANSFER OF POWER AND DATA

This text discusses the possibilities when designing a wireless inductive link that works both as an energy link, to power up a remote device, as well as a communication link to retrieve data and to write data to the same remote device, using the same set of inductive coils. Datatransmission from the measurement system to a base unit is achieved by applying absorption modulation, datatransmission to the measurement system by applying amplitude modulation. Some basic formulae and design considerations are given, and a full example applicable to an implantable device is given.

Feasibility of in utero telemetric fetal ECG monitoring in a lamb model

Objectives: If fetal ECG (fECG) devices could be miniaturized sufficiently, one could consider their implantation at the time of fetal surgery to allow permanent monitoring of the fetus and timely intervention in the viable period. We set up an experiment to evaluate the feasibility of in utero direct fECG monitoring and telemetric transmission using a small implantable device in a lamb model. Methods: A 2-lead miniature ECG sensor (volume 1.9 cm3; weight 3.9 g) was subcutaneously implanted in 2 fetal lambs at 122 days gestation (range 119–125; term 145 days). The ECG sensor can continuously register and transmit fECG. The signal is captured by an external receiving antenna taped to the maternal abdominal wall. We developed dedicated software running on a commercial laptop for on-line analysis of the transmitted fECG signal. This was a noninterventional study, i.e. daily readings of the fECG signal were done without clinical consequences to the observations. Results: fECG could be successfully registered, transmitted by telemetry and analyzed from the moment of implantation till term birth in one case (24 days). In the second case, unexplained in utero fetal death occurred 12 days after implantation. In this subject, agonal fECG changes were recorded. Conclusion: An implanted miniature (<2 ml) ECG sensor can be used to retrieve, process and transmit continuously a qualitative fECG signal in third-trimester fetal lambs. The telemetric signal could be picked up by an external antenna located within a 20-cm range. In this experiment, this was achieved through taping the external receiver to the maternal abdomen. Any acquired signal could be transmitted to a commercially available laptop that could perform on-line analysis of the signal.

A Differential Pressure Approach to Spirometry

This paper presents the design, implementation and measurements of a spirometer based on differential pressure sensing. A system which fulfills the last medical standard specifications has been designed exploiting the Venturi tube principle. A fully operating prototype has been tested, and data have been subsequently analyzed. Air flows up to 14 L/s can be measured with an accuracy of 0.2 L/s. Data acquisition software and user interface were developed.

Integrating wireless ECG monitoring in textiles

This paper reports for the first time on the realization of a garment embedded patient monitoring system, including wireless communication and inductive powering. The developed system is primarily intended for the continuous monitoring of the electrocardiogram (ECG) of children with an increased risk of SIDS (sudden infant death syndrome). The sensors and the antenna are made out of textile materials. All electronics are mounted on a flexible circuit to facilitate integration in the babys pyjamas. A significant increase in the comfort of patient and nursing staff is achieved by this integration in textiles. A prototype baby suit was fabricated and successfully tested by a 21 weeks old baby.

EXCITED-STATE PROBING OF ASSOCIATIVE AND COVALENT MACROMOLECULES

The use of fluorescence spectroscopy in the study of associative phenomena is illustrated . The use of standard global of and global compartmental analysis in a number of complex systems is clearly shown. Association between detergent molecules and between detergents and polymers was analysed and the different parameters characterising such an interaction evaluated. Associative phenomena in covalent polymers such as dipole-dipole interactions in halato-telechelic polymers and in syndiotactic polymethylmethacrylate were investigated. The rate constants of inter and intramolecular interactions in halato-telechelic polymer were determined through a systematic analysis of the different interactions using global tricompartmental analysis of fluorescence decays combined with a scanning technique to estimate the rate constants. Fluorescence polarization and changes in fluorescence decay times in the temperature range of gelation reveal a stepwise mechanism in the gelation of s-PMMA.

Compartmental analysis of the fluorescence decay surface of intramolecular two-state excited-state processes with added quencher

The fluorescence decay analysis of intramolecular two-state excited-state processes with added quencher is discussed in terms of compartments. The kinetic equations specifying the fluorescence decay and the time-course of the two excited-state species concentrations are expressed in terms of the rate constants and the spectroscopic parameters b1 and c1. b1 and c1 are respectively the relative absorbance and the normalized spectral emission weighting factor of species 1. The report investigates what has to be known beforehand to determine all relevant parameters. The results of this identifiability study indicate that the following conditions have to be satisfied in order to make an intramolecular two-state excited-state system with added quencher identifiable. First, at least three different quencher concentrations must be used. Second, the two rate constants of quenching must be different. Third, at least one parameter must be known. This parameter can be (1) one rate constant which is not a rate constant of quenching, (2) one b1 value or, (3) one c1 value. In each of these cases an alternative set of system parameters is mathematically possible. A unique solution is guaranteed when the fluorescence decays of a quenched model compound are included in the compartmental analysis.