Water Jet Actuation for Ultra-low Cost Endoscopy: Characterization of Miniature Nozzles Fabricated by Rapid Prototyping

Gastric cancer is the second leading cause of cancer death worldwide, accounting for over 10% of incidence cancers. Screening programs have been shown to be effective in reducing the mortality rate through early detection; however, many factors hinder the widespread implementation of these programs in low resource settings due to their high capital cost (associated mainly with cable driven units), limited portability, and reprocessing/contamination concerns. The Hydrojet endoscopic platform was developed as a low-cost alternative for gastric cancer screening in low-income countries. The capsule, completely made of bio-compatible plastic through rapid prototyping, uses pressurized water ejected from miniature nozzles to inspect the stomach. In order to achieve full controllability of the system inside the stomach, force characterization of the water jet actuators is needed. This work aimed to: i) characterize the relationship between thrust (with changes in outer diameter) and flow rate of miniature nozzles fabricated by rapid prototyping and ii) estimate the error due to the fabrication process. Results show that the experimental reaction thrust has a comparable trend to the analytical model hence a shape coefficient can be calculated and the actual thrust estimated at each point. Experimental results show the error due to rapid prototyping to be linear, thereby allowing for algorithmic compensation

Image Registered Gastroscopic Ultrasound (IRGUS) in human subjects: A pilot study to assess feasibility

Background and study aims: Endoscopic ultrasound (EUS) is a complex procedure due to the subtleties of ultrasound interpretation, the small field of observation, and the uncertainty of probe position and orientation. Animal studies demonstrated that Image Registered Gastroscopic Ultrasound (IRGUS) is feasible and may be superior to conventional EUS in efficiency and image interpretation. This study explores whether these attributes of IRGUS will be evident in human subjects, with the aim of assessing the feasibility, effectiveness, and efficiency of IRGUS in patients with suspected pancreatic lesions. Patients and methods: This was a prospective feasibility study at a tertiary care academic medical center in human patients with pancreatic lesions on computed tomography (CT) scan. Patients who were scheduled to undergo conventional EUS were randomly chosen to undergo their procedure with IRGUS. Main outcome measures included feasibility, ease of use, system function, validated task load (TLX) assessment instrument, and IRGUS experience questionnaire. Results: Five patients underwent IRGUS without complication. Localization of pancreatic lesions was accomplished efficiently and accurately (TLX temporal demand 3.7%; TLX effort 8.6%). Image synchronization and registration was accomplished in real time without procedure delay. The mean assessment score for endoscopist experience with IRGUS was positive (66.6 ±29.4). Real-time display of CT images in the EUS plane and echoendoscope orientation were the most beneficial characteristics. Conclusions: IRGUS appears feasible and safe in human subjects, and efficient and accurate at identification of probe position and image interpretation. IRGUS has the potential to broaden the adoption of EUS techniques and shorten EUS learning curves. Clinical studies comparing IRGUS with conventional EUS are ongoing