Soft Ring Actuation Based Gastric Simulator: Design, Modelling and Experiments

Abstract

The radial contractions of the gastric muscle play a key role of breaking down and transporting food in the human stomach. The radial contractions periodically propagate through the stomach and constitute the gastric motility, also called peristaltic contractions. The force, amplitude and frequency of these contractions are relevant to massaging and transporting the food contents in the gastric lumen. However, existing gastric simulators have not faithfully replicated the gastric anatomy and motility. Soft robotic techniques that feature compliance and adaptability offer an alternative to overcome this limitation. The aim of this study is to develop a soft ring actuation based gastric simulator to emulate the gastric anatomy and peristaltic contractions. It is motivated by the demands from research fields of the food, nutrition science and digestion. This simulator can advance the investigation of the in vivo digestion process of food and pharmaceuticals, and promote the development of new technologies such as gastric pacemakers and microrobots that work in the human stomach. This thesis investigates the design, modelling and experiments of a soft ring actuation based gastric simulator. It starts by a comprehensive literature review on human stomach, existing gastric simulators and relevant soft robotic techniques. Technical requirements on the soft robotic gastric simulators are formulated according to the review. Following that, the conceptualisation of the gastric simulator involving a series of soft ring actuation is proposed. The feasibility of the conceptual design is validated via pilot experiments. The design and modelling of the soft ringshaped actuator is proposed and validated for understanding the radial contraction. Besides, a soft sensor is integrated into the surface of the ring-shaped actuator for the resultant embedded sensing capability. This integration offers the possibility of closed-loop control of the actuation on its own. As a step further to fulfil the technical requirements and conceptualisation, a soft ring actuation based gastric simulator (SoGut) is developed and characterised. Compared to existing simulators, SoGut can emulate peristaltic contractions in an anatomically realistic manner. It will serve as an important new tool to investigate digestion and promote novel technologies for the human stomach.