Research Papers

Design of a Wireless Medical Capsule for Measuring the Contact Pressure Between a Capsule and the Small Intestine

[+] Author and Article Information
Pengbo Li

Mechanical and Material Engineering,
University of Nebraska-Lincoln,
W342 Nebraska Hall,
Lincoln, NE 68588-0526
e-mail: pengbo.li@huskers.unl.edu

Craig Kreikemeier-Bower

School of Veterinary,
University of Nebraska-Lincoln,
Mussehl Hall 110,
Lincoln, NE 68583

Wanchuan Xie

Mechanical and Material Engineering,
University of Nebraska-Lincoln,
W342 Nebraska Hall,
Lincoln, NE 68588-0526

Vishal Kothari

Department of Surgery,
University of Nebraska Medical Center,
Nebraska Medicine—Bariatrics Center
4400 Emile Street,
Omaha, NE 68198

Benjamin S. Terry

Department of Mechanical and
Materials Engineering,
University of Nebraska-Lincoln,
360 Walter Scott Engineering Center,
Lincoln, NE 68508

Manuscript received November 2, 2016; final manuscript received March 4, 2017; published online March 24, 2017. Assoc. Editor: Nathan Sniadecki.

J Biomech Eng 139(5), 051003 (Mar 24, 2017) (8 pages) Paper No: BIO-16-1433; doi: 10.1115/1.4036260 History: Received November 02, 2016; Revised March 04, 2017

A wireless medical capsule for measuring the contact pressure between a mobile capsule and the small intestine lumen was developed. Two pressure sensors were used to measure and differentiate the contact pressure and the small intestine intraluminal pressure. After in vitro tests of the capsule, it was surgically placed and tested in the proximal small intestine of a pig model. The capsule successfully gathered and transmitted the pressure data to a receiver outside the body. The measured pressure signals in the animal test were analyzed in the time and frequency domains, and a mathematic model was presented to describe the different factors influencing the contact pressure. A novel signal processing method was applied to isolate the contraction information from the contact pressure. The result shows that the measured contact pressure was 1.08 ± 0.08 kPa, and the small intestine contraction pressure's amplitude and rate were 0.29 ± 0.046 kPa and 12 min−1. Moreover, the amplitudes and rates of pressure from respiration and heartbeat were also estimated. The successful preliminary evaluation of this capsule implies that it could be used in further systematic investigation of small intestine contact pressure on a mobile capsule-shaped bolus.

Copyright © 2017 by ASME
Topics: Pressure , Design
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Fig. 1

(a) Interaction between the capsule and the small intestine (Pc : contact pressure and Pi : intraluminal pressure), (b) 3D model of the designed capsule, (c) assembly of pressure sensor 2, and (d) prototype of the capsule

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Fig. 2

(a) Architecture of the pressure measurement system, (b) MCU board, (c) top view of IMU board, (d) bottom view of IMU board, and (e) receiver

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Fig. 3

(a) Static test result (Pm : measured pressure by P2 and Pr : actual pressure applied on P2), (b) dynamic test result (Pm : measured pressure by P2 and Pr : actual pressure applied on P2), (c) transmission validation setup, and (d) animal test setup

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Fig. 4

(a) Gathered pressure signals in the animal test and (b) contact pressure

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Fig. 5

(a) One section of Pc with respiration and heartbeat induced pressure, (b) one section of Pc with contraction, respiration, and heartbeat induced pressure, and (c) fitting result with contact pressure model (Phb: heartbeat induced pressure; Pr: respiration induced pressure; Pt: tissue contraction induced pressure; Pc,m: model fitted contact pressure; and Pc,e: experimental contact pressure)

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Fig. 6

(a) FFT of P1 and (b) FFT of Pc

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Fig. 7

(a) Flowchart of the signal processing method, (b) isolated contraction induced pressure signal, and (c) FFT of contraction induced pressure signal




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