Design of a high-sensor count fibre optic manometry catheter for in-vivo colonic diagnostics

CSIRO Materials Science and Engineering, PO Box 218, Lindfield, NSW 2070, Australia.
Optics Express (Impact Factor: 3.49). 12/2009; 17(25):22423-31. DOI: 10.1364/OE.17.022423
Source: PubMed


The design of a fibre Bragg grating based manometry catheter for in-vivo diagnostics in the human colon is presented. The design is based on a device initially developed for use in the oesophagus, but in this instance, longer sensing lengths and increased flexibility were required to facilitate colonoscopic placement of the device and to allow access to the convoluted regions of this complex organ. The catheter design adopted allows the number of sensing regions to be increased to cover extended lengths of the colon whilst maintaining high flexibility and the close axial spacing necessary to accurately record pertinent features of peristalsis. Catheters with 72 sensing regions with an axial spacing of 1 cm have been assembled and used in-vivo to record peristaltic contractions in the human colon over a 24hr period. The close axial spacing of the pressure sensors has, for the first time, identified the complex nature of propagating sequences in both antegrade (towards the anus) and retrograde (away from the anus) directions in the colon. The potential to miss propagating sequences at wider sensor spacings is discussed and the resultant need for close axial spacing of sensors is proposed.

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Available from: Michal M Szczesniak, Aug 26, 2014
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    • "Each FBG can be tuned to reflect a different wavelength of light; hence the entire array can be interrogated simultaneously by observing the optical spectrum covering the reflected peaks from every FBG in the array. The pressure transducer design was based on that developed by some of the authors (JA & IU) for in-vivo measurement of peristalsis in the human gut [7], [8] and consists of a rigid metallic substrate into which one of the FBG elements of the DTG array was rigidly bonded. During the bonding process the fiber was constrained to form an arc, shown schematically in Fig. 1, and was then covered with a tightly fitting pressure sensitive outer sleeve that induces a sideways deflection of the fiber towards the axis of the substrate (indicated by an arrow in the Figure) as the external pressure varies. "
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    ABSTRACT: Distributed pressure sensing arrays fabricated from fiber Bragg gratings have been demonstrated for real-time monitoring of the dynamic subsurface pressures beneath water waves in a wave tank. Two sensing arrays were used to monitor horizontal and vertical pressures in the tank as periodic wave trains passed overhead. The horizontal and vertical arrays contained 90 and 35 sensing elements, respectively, spaced at 1-cm intervals allowing highly accurate spatial resolution to be achieved in both orientations. The wave tank paddle was programmed to generate wave-trains varying from ${sim}{5}$ - to 30-cm peak-to-trough and the pressures measured using the fiber optic array were validated using commercial piezo-electric pressure sensors and video image analysis. The length and sensor separation of the fiber optic sensing array can be varied to suit the location under test, and the fiber optic elements make the devices inherently resistant to corrosion and electromagnetic interference.
    Full-text · Article · Aug 2014 · IEEE Sensors Journal
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    • "The colon wall locally is able to accommodate a 40% expansion but the actual development of the expansion needs to be driven by fluid pressure within. Data attained through in vivo high-resolution colonic manometry [26] suggest that colonic contractions occur over 2–4 cm. For the base case of the model, we have chosen a length of 4 cm as a starting point. "
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    ABSTRACT: Complex relationships exist between gut contractility and the flow of digesta. We propose here a Smoothed Particle Hydrodynamics model coupling the flow of luminal content and wall flexure to help investigate these relationships. The model indicates that a zone of muscular relaxation preceding the contraction is an important element for transport. Low pressures in this zone generate positive thrust for low viscosity content. The viscosity of luminal content controls the localization of the flow and the magnitude of the radial pressure gradient and together with contraction amplitude they control the transport rate. For high viscosity content, high lumen occlusion is required for effective propulsion.
    Full-text · Article · Jan 2012 · Computers in Biology and Medicine
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    • "If not properly accounted for, these strain-induced wavelength shifts will be incorrectly attributed to pressure (i.e., pressure measurement error). The sensors described by Arkwright et al. (2009) and Voigt et al. (2010) address strain-sensitivity through sensor design and the use of a protective sheath that surrounds the sensor. The sensor design presented here does not compensate for axial strains that could result from peristalsis. "
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    ABSTRACT: In this work, a new distributed pressure measurement system is presented that is based on multiplexed in-fibre Bragg gratings housed within a flexible superstructure. The sensor super-structure comprises hypodermic tubing and several spacers and pressure diaphragms that together define the sensing locations and provide mechanical support to the Bragg gratings. Linear elasticity and strain-optic models are used to predict sensor performance in terms of sensitivity to hydrostatic pressure. Model predictions are validated through experimental calibration and indicate pressure sensitivities as high as 2.94 nm/MPa (MegaPascal) for a prototype with 1 mm outside diameter. The maximum measurement error from all calibration experiments is 3.4% of full-scale applied pres-sure. To the authors' knowledge, this is the smallest reported mul-tiplexed pressure sensor that is based on Bragg gratings. Due to its small size, this sensor could potentially be applied in medical applications that existing sensors are too large for, specifically in angiography procedures for coronary arteries.
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