A disposable, soft-tethered, swallowable, endoscopic capsule that uses water-jet actuation for mobility
Flexible endoscopes are actuated using tendons (Bowden cables). Even if this is a simple form of actuation, cable insertion during fabrication or repairing of the device is performed manually and this is a time-consuming procedure. For this reason, we identified Bowden cables as the main item of cost in a flexible endoscope and, leveraging our pioneering work in the field of robotic capsule endoscopes, we are developing a disposable, soft-tethered, swallowable, endoscopic capsule. Design innovations include water-jet actuation for mobility and visualization, a portable platform, disposable components, and autonomous operation based on image analysis and feature extraction.
Basically, the platform called HydroJet consists in a multi-lumen catheter with a capsule attached at the end. Three of the lumens of the tether are used to inject pressurized water that will be ejected from three nozzles placed on the capsule body and space 120°from each other. In this way, as soon as the water comes out from the nozzles, the capsule can move with 2 degrees of freedom relying on reaction forces. The system is equipped with a camera which remains sterile until the end of the endoscopy since it is sealed inside the capsule’s body. At the end of the procedure, the multi-lumen catheter and the capsule will be disposed and the camera retrieved in order to be reused for the following procedure. By doing this, a goal of £2 per procedure can be achieved.
No pumps or compressors have been used to obtain pressurized water, this way maintaining the platform portability and removing the need for external power supply. A pressurized air tank is used instead to pressurize another tank filled with water. The water reaches a manifold which splits the flow into three lines, each of them passes through a pinch valve and then connects to the multi-lumen catheter providing water to the nozzles. Pinch valves control the water flow running in each line and the user can control valves, and so the position of the capsule, using a joystick. The proposed platform is designed to fit in a single suitcase (airline carry-on size, 10kg) and operate autonomously without the need for a gastroenterologist or a skilled clinician.
Campisano, F., Gramuglia, F., Dawson, I.R., Lyne, C.T., Izmaylov, M.L., Misra, S., De Momi, E., Morgan, D.R., Obstein, K.L. and Valdastri, P., 2017. “Gastric Cancer Screening in Low-Income Countries“. IEEE Robotics & Automation Magazine, 24(2), pp.73-81.
Caprara, R., Obstein, K.L., Scozzarro, G., Di Natali, C., Beccani, M., Morgan, D.R. and Valdastri, P., 2015. “A platform for gastric cancer screening in low-and middle-income countries“. IEEE Transactions on Biomedical Engineering, 62(5), pp.1324-1332.
The HydroJet platform has been tested in order to evaluate the performances of the system in terms of thrust generated by water jets and capsule’s workspace. With the water tank pressurized at 80 psi, the capsule is able to move in a quasi-hemispherical (120 mm maximum diameter) and symmetric workspace.
Comparative trials have also been performed, in order to compare the performances of both a flexible endoscope and the HydroJet when they are maneuvered by a novice and by an expert gastroenterologist trying to visualize six landmarks inside a simulation environment. Results showed that HydroJet platform has to be optimized in order to be able to compete with a flexible endoscope.
The aim of this research is to establish a feasible model for gastroesophageal cancer screening at an ultra-low cost that can be implemented in rural and poorly resourced areas. The approach can be extended to other low- and middle-income countries (nearly 70% of gastric and oesophageal cancer cases are concentrated in these areas) or equally to modern healthcare systems, where cost savings may be achieved through performing screening in day care units.