Fundamentals of the gut for capsule engineers

Abstract

The gastrointestinal (GI) tract is a complex environment comprised of the mouth, esophagus, stomach, small and large intestines, rectum and anus, which all cooperate to form the complete working GI system. Access to the GI using endoscopy has been augmented over the past several decades by swallowable diagnostic electromechanical devices, such as pill cameras.Research continues today and into the foreseeable future on new and more capable miniature devices for the purposes of systemic drug delivery, therapy, tissue biopsy, microbiome sampling, and a host of other novel ground-breaking applications. The purpose of this review is to provide engineers in this field a comprehensive reference manual of the GI environment and its complex physical, biological, and chemical characteristics so they can more quickly understand the constraints and challenges associated with developing devices for the GI space. To accomplish this, the work reviews and summarizes a broad spectrum of literature covering the main anatomical and physiological properties of the GI tract that are pertinent to successful development and operation of an electromechanical device. Each organ in the GI is discussed in this context, including the main mechanisms of digestion, chemical and mechanical processes that could impact devices, and GI motor behavior and resultant forces that may be experienced by objects as they move through the environment of the gut.

Engineering Auxetic Cylinders and Intestine to Improve Longitudinal Intestinal Lengthening and Tailoring Procedure

“…In Figure 4 a, the stress–strain curve of the porcine intestine is reported; from this curve, we obtained the data of elastic modulus (0.1 MPa) and tensile strength (1.25 × 10 −2 MPa) that were in agreement with those reported by Barducci et al [ 22 ]. Moreover, Figure 4 b shows the mold used to prepare the samples and the image of the obtained hollow cylinder.…”

Peptide-Functionalized Silk Fibers as a Platform to Stabilize Gelatin for Use in Ingestible Devices

“…Similarly, the dissolution time has to be correlated to the mechanical properties. For our experiments, we consider the transit time as the time that the food takes to reach the large and small intestine, and it was estimated that the gastric time was between 35.5 min and 57 min, while the transit time for the small intestine was about 261 min [ 39 , 40 ]. The pH-dependent dissolution appearance and data of samples are reported in Figure 5 a,b.…”

Smart pills for gastrointestinal diagnostics and therapy

“…Increasing smart pill functionality to incorporate navigation, multiple diagnostic or therapeutic modalities, and localisation, coupled with design constraints to ensure ease of ingestion and safety [205], will bring new challenges. For example, greater systems integration brings the risk of power consumption will be especially challenging since batteries currently take up a large amount of space in capsule endoscopes.…”