The evaluation of the tone and contractile patterns of the gastrointestinal (GI) tract via manometry is essential for the diagnosis of GI motility disorders. However, manometry is expensive and relies on complex and bulky instrumentation. Here we report the development and performance of an inexpensive and easy-to-manufacture catheter-like device for capturing manometric data across the dynamic range observed in the human GI tract. The device, which we designed to resemble the quipu—knotted strings used by Andean civilizations for the capture and transmission of information—consists of knotted piezoresistive pressure sensors made by infusing a liquid metal (eutectic gallium-indium) through thin silicone tubing. By exploring a range of knotting configurations, we identified optimal design schemes that led to sensing performances comparable to those of commercial devices for GI manometry, as we show for the sensing of GI motility in multiple anatomic sites of the GI tract of anaesthetized pigs. Disposable and customizable piezoresistive catheters may broaden the use of GI manometry in low-resource settings.
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We thank A. M. Hayward, K. Ishida and J. Jenkins for supervising and performing the in vivo experiments using Yorkshire swine models; M. Kolle for insightful discussions on knot mechanics; and H. Luan for helping with finite-element modelling. This work was supported in part by the Karl van Tassel (1925) Career Development Professorship and the Department of Mechanical Engineering, MIT.
The authors report a patent application (U.S. Provisional Application No. 63/301,491) describing the system described for manometric evaluation. Complete details of all for-profit and not-for-profit relationships for G.T. are included in the Supplementary Information. The other authors declare no competing interests.
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Supplementary Table 1, Figs. 1–19, References, video captions and details of competing interests for G.T.
Formation of an elastic overhand knot using finite-element simulations.
Finite-element simulations of knot compression.
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Nan, K., Babaee, S., Chan, W.W. et al. Low-cost gastrointestinal manometry via silicone–liquid-metal pressure transducers resembling a quipu. Nat. Biomed. Eng (2022). https://doi.org/10.1038/s41551-022-00859-5