The development of a physical intestine model, and the experimental study of flow patterns and mass transfer

Abstract

Studying the complex digestion process in the small intestine and stomach can allow us to understand the digestion and absorption of food and drugs. For food digestion, the mass transfer rate is an important parameter affecting the movement of nutrients. Benzoic acid tablets have been used to probe the differences in external mass-transfer coefficients within a piece of equipment and between different types of equipment, including a beaker and stirrer system and the USP dissolution apparatus Ⅱ (paddle). It is possible to obtain similar mass transfer coefficients in different systems by adjusting the operating conditions when setting up the in-vitro systems.

An artificial human intestine model has been produced using thermoplastic polyurethane, which is an elastomer. It can simulate the peristaltic movement by changing frequency and amplitude. This elastic in vitro model has been generated by using 3D printing technology. The flow pattern of fluorescein dye has been studied with the help of cameras and computer analysis programs. By measuring the mechanical property of this TPU intestine model, a fluid-structure interaction model has been simulated. The interaction between a movable structure and the internal fluid flow can be analysed through FSI simulation to compare with the physical experimental results. The dye concentration magnitude generally matched well between the simulation and experiment results.

A biocompatible hydrogel has been used to develop a transparent and elastic in-vitro intestine model. The flow pattern of the red food dye inside this model has been studied with the help of a camera-computer analysis system. In addition, this in-vitro intestine model is used to measure the mass transfer coefficients of the tablets. The transparency of the in vitro intestine model allowed for visual observation tracking of food pieces. This model is low-cost and easy to construct and operate.