Lecturer/Resarcher, Universite des Montagnes
Use of local materials and available electronics to develop biomedical devices for poor countries
State of the art health care devices is not always available in Sub-Saharan countries and those that are obtained through donations are not suited for its environment. When these device break down there are no trained professionals to repair them. Hence there is an urgent need of both training qualified personnel and also developing low cost and highly performance diagnosis devices. In my research I design and develop cheap medical devices that can provide solutions to local problems. Among the devices designed are a neonatal incubator, an oxygen concentrator, an ECG system and a bioimpedance spectroscopy system (BIS). The BIS is the project I am currently working on. Bioimpedance is the passive electrical impedance of biological tissues. It is obtained by letting electric current flows through the tissue and the voltage drop measured. This measured voltage and current are used to estimate the bioimpedance of the tissue. This bioimpedance varies with frequency of the electric current and different tissue types. The goal of BIS is to measure the impedance spectra of biological tissues. BIS can be used for the evaluation inter-cellular fluid (ICF), extra-cellular fluid (ECF), total body water (TBW), fat-free mass (FFM) that leads to the diagnosis of various diseases. Given that the existing BIS system found in the market are expensive my research is to be able to develop a cheaper device with similar performance as the commercial ones. Various technical consideration needs to be taken to achieve that. The current source needs to have high output impedance, voltage sensing should be done in such a way that noise and interference in minimized, measurement should be fast and accurate for real-time monitoring. I published a couple of papers on this work and it is projected by a full and functioning BIS system can be produced shortly.
Abstract: When we use a conductive fabric as a pressure sensor, it is necessary to quantitatively understand its electromechanical property related with the applied pressure. We investigated electromechanical properties of three different conductive fabrics using the electrical impedance spectroscopy (EIS). We found that their electrical impedance spectra depend not only on the electrical properties of the conductive yarns, but also on their weaving structures. When we apply a mechanical tension or compression, there occur structural deformations in the conductive fabrics altering their apparent electrical impedance spectra. For a stretchable conductive fabric, the impedance magnitude increased or decreased under tension or compression, respectively. For an almost non-stretchable conductive fabric, both tension and compression resulted in decreased impedance values since the applied tension failed to elongate the fabric. To measure both tension and compression separately, it is desirable to use a stretchable conductive fabric. For any conductive fabric chosen as a pressure-sensing material, its resistivity under no loading conditions must be carefully chosen since it determines a measurable range of the impedance values subject to different amounts of loadings. We suggest the EIS method to characterize the electromechanical property of a conductive fabric in designing a thin and flexible fabric pressure sensor.
Pub.: 04 Jun '14, Pinned: 13 Apr '18