J.L. Gonzalez

The University of Calgary, Calgary, Alberta, Canada

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Publications (3)0 Total impact

  • J L Gonzalez, D C Sadowski, M P Mintchev
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    ABSTRACT: 24-hour catheter-based ambulatory pH and impedance monitoring is an essential tool for diagnosing esophageal disorders. However, catheter-based monitoring systems are uncomfortable and interfere with normal activities of the patient. To overcome these disadvantages, different wireless monitoring systems have been proposed. However, efficient ways to position and hold wireless capsules are lacking. Currently there is a need to develop safe and reliable methods to hold an esophageal wireless monitoring system in position for 24 hours. Friction-assisted magnetic holding is proposed as an alternative to conventional holding techniques. Permanent magnet and electromagnet designs with the required characteristics to achieve this task were computer-designed and simulated. The size and power requirements of the magnets were considered. Simulation results were verified using laboratory experiments. Permanent neodymium magnets offered the best performance for the intended application. The obtained results show the feasibility of friction-assisted magnetic holding for esophageal monitoring. Improvements to the thread design, friction enhancing pins, magnetic shielding and encapsulation methods are necessary for in vivo testing.
    Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 02/2006; 1:5944-7. DOI:10.1109/IEMBS.2006.260543
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    ABSTRACT: Biomedical optical impedance sensors involve image processing of light blobs to extract information regarding a process such as pressure. These sensors utilize a light source to illuminate an imager chip. The edges of the light blob, its diameter and location are parameters of interest to characterize pressure dynamics. CMOS technology allows the capture and processing of an image on a single chip. However, specialized imagers, optimized for extracting dynamic information from light blobs for this application, have not been proposed. A CMOS active pixel sensor (APS) imager, capable of processing all parameters of interest in a light blob, is presented. Innovative, efficient and easy-to-implement techniques for cross-sectional diameter estimation and edge detection are proposed. The simulation results showed the feasibility of the proposed design. This chip was designed using 0.18 μm technology and is currently being fabricated. It operates at 1.8 V.
    Circuits and Systems, 2005. ISCAS 2005. IEEE International Symposium on; 06/2005
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    ABSTRACT: Pressure, pH and bolus transit measurements are commonly used for diagnosing esophageal motility disorders. In the present study, a probe that integrates novel techniques for monitoring all variables of interest for esophageal testing is proposed. Innovative catheter design offers proper selection of frequencies and electrode arrangement for enhanced impedance-based pH and bolus transit monitoring. In addition, a novel optical method for contraction detection is proposed. A model of the esophagus was used to test the multi-sensor probe. Repeatability of the obtained impedance measurements related to pH was tested. The obtained results satisfied the requirements of DeMeester and Johnson scoring system for pH measurements. Bolus transit and reflux periods were simulated in the test model and were successfully identified. Optical detection of intraluminal pressure and subsequent reconstruction of esophageal wall dynamics were also explored. Experimental results showed the feasibility of the suggested integrated sensor approach for esophageal testing.
    Sensors, 2004. Proceedings of IEEE; 11/2004