Stiffness Investigations of A Soft Robot Manipulator for Affordable Endotracheal Intubation Devices

Endotracheal intubation (ETI) is a crucial procedure, performed approximately 15 million times annually in the USA alone [1]. To enhance the efficiency of ETI, especially in difficult circumstances, tools like stylets and introducers (bougies) are commonly utilized [2]. One of the most widely used aid tools known as an introducer, also referred to as “bougie“, is a malleable rod, mostly made of low-density polyethylene (LDPE) or polyvinyl chloride (PVC), is used as a guide to ‘railroad’ the ETT right into the laryngeal opening [3]. Existing introducers are mainly passive instruments, having to be pre-shaped only before the insertion. The lack of controllability, along with the property of the material that is stiffer than the tissue with which the device will interact, can lower the first-attempt intubation success rate [2], [4] and may also lead to a higher risk of injuring the patient [5]. In this work, we propose a design of a soft pneumatic continuum actuator to replace the structure located on the distal tip of an introducer as shown in the schematic in Fig. 1A. This means that the actuator should have sufficient rigidity to bend the rest of the shaft to which it is attached. In this work, we investigate a way to increase the stiffness of a soft robot manipulator by 1) adding an inextensible central rod with a higher bending stiffness than the silicone and 2) investigating the effect of pressurization in each chamber.