Towards minimally invasive monitoring for gastroenterology -An external Squamocolumnar Junction Locator

James G H Whiting, Nasser Djennati, Yeong Yeh Lee, Elaine V Robertson, Mohammad H Derakhshan, Patricia Connolly, Kenneth E L McColl

Research output: Chapter in Book/Report/Conference proceedingConference contribution book

2 Citations (Scopus)

Abstract

Transient lower oesophageal sphincter relaxations (TLOSRs) occur frequently and are the main mechanism of acid reflux. The only means of currently detecting TLOSRs is intra-luminal manometry and the probes themselves may stimulate TLOSRs. The squamo-columnar junction moves 4-5 centimeters proximally during TLOSRs and this provides a means of detecting such episodes. The objective of this work is to develop a sensor system capable of detecting the movement of a miniature magnet attached to the squamo-columnar junction from outside the body and thus allow detection of TLOSRs without the artifact associated with intraluminal detection probes. A GaAs Hall effect sensor was selected and an alternating current supply was developed with a combination of filters and a Phase Sensitive Detector, to detect the magnet. The oscillation frequency of the current was chosen in order to reduce electronic noise, and filtering outside this frequency means the signal to noise ratio was greatly improved. The phase sensitive detector was employed to accurately convert the amplitude of the sensor's output to a DC signal. With the addition of paired Flux Concentrators increases the range up to 10.2 centimetres, an improvement of 580% over commercial Hall effect sensors. The AC circuit and flux concentrator device far exceeds the sensitivity of the current Hall effect sensors supplied in the market, by rejecting noise and providing accurate measurement over significantly larger distances. The development of this sensor has applications beyond this specific medical device.
Original languageEnglish
Title of host publicationProceedings of the 2012 Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC)
PublisherIEEE
Pages1574-1577
Number of pages4
ISBN (Print)978-1-4244-4119-8
DOIs
Publication statusPublished - Sep 2012

Fingerprint

Lower Esophageal Sphincter
Gastroenterology
Magnets
Equipment and Supplies
Manometry
Signal-To-Noise Ratio
Artifacts
Noise
Acids

Keywords

  • electric sensing devices
  • current oscillation frequency
  • gallium arsenide
  • magnetic field
  • oesophagus squamous epithelium
  • biomedical MRI

Cite this

Whiting, J. G. H., Djennati, N., Lee, Y. Y., Robertson, E. V., Derakhshan, M. H., Connolly, P., & McColl, K. E. L. (2012). Towards minimally invasive monitoring for gastroenterology -An external Squamocolumnar Junction Locator. In Proceedings of the 2012 Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) (pp. 1574-1577). IEEE. https://doi.org/10.1109/EMBC.2012.6346244
Whiting, James G H ; Djennati, Nasser ; Lee, Yeong Yeh ; Robertson, Elaine V ; Derakhshan, Mohammad H ; Connolly, Patricia ; McColl, Kenneth E L. / Towards minimally invasive monitoring for gastroenterology -An external Squamocolumnar Junction Locator. Proceedings of the 2012 Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC). IEEE, 2012. pp. 1574-1577
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Whiting, JGH, Djennati, N, Lee, YY, Robertson, EV, Derakhshan, MH, Connolly, P & McColl, KEL 2012, Towards minimally invasive monitoring for gastroenterology -An external Squamocolumnar Junction Locator. in Proceedings of the 2012 Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC). IEEE, pp. 1574-1577. https://doi.org/10.1109/EMBC.2012.6346244

Towards minimally invasive monitoring for gastroenterology -An external Squamocolumnar Junction Locator. / Whiting, James G H; Djennati, Nasser; Lee, Yeong Yeh; Robertson, Elaine V; Derakhshan, Mohammad H; Connolly, Patricia; McColl, Kenneth E L.

Proceedings of the 2012 Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC). IEEE, 2012. p. 1574-1577.

Research output: Chapter in Book/Report/Conference proceedingConference contribution book

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AU - Whiting, James G H

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AU - Connolly, Patricia

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AB - Transient lower oesophageal sphincter relaxations (TLOSRs) occur frequently and are the main mechanism of acid reflux. The only means of currently detecting TLOSRs is intra-luminal manometry and the probes themselves may stimulate TLOSRs. The squamo-columnar junction moves 4-5 centimeters proximally during TLOSRs and this provides a means of detecting such episodes. The objective of this work is to develop a sensor system capable of detecting the movement of a miniature magnet attached to the squamo-columnar junction from outside the body and thus allow detection of TLOSRs without the artifact associated with intraluminal detection probes. A GaAs Hall effect sensor was selected and an alternating current supply was developed with a combination of filters and a Phase Sensitive Detector, to detect the magnet. The oscillation frequency of the current was chosen in order to reduce electronic noise, and filtering outside this frequency means the signal to noise ratio was greatly improved. The phase sensitive detector was employed to accurately convert the amplitude of the sensor's output to a DC signal. With the addition of paired Flux Concentrators increases the range up to 10.2 centimetres, an improvement of 580% over commercial Hall effect sensors. The AC circuit and flux concentrator device far exceeds the sensitivity of the current Hall effect sensors supplied in the market, by rejecting noise and providing accurate measurement over significantly larger distances. The development of this sensor has applications beyond this specific medical device.

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Whiting JGH, Djennati N, Lee YY, Robertson EV, Derakhshan MH, Connolly P et al. Towards minimally invasive monitoring for gastroenterology -An external Squamocolumnar Junction Locator. In Proceedings of the 2012 Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC). IEEE. 2012. p. 1574-1577 https://doi.org/10.1109/EMBC.2012.6346244