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

The adult large bowel: describing environment morphology for effective biomedical device development

An understanding of the biological environment, and in particular the physical morphology, is crucial for those developing medical devices and software applications. It not only informs appropriate design inputs, but provides the opportunity to evaluate outputs via virtual or synthetic models before investing in costly clinical investigations. The large bowel is a pertinent example, having a major demand for effective technological solutions to clinical unmet needs. Despite numerous efforts in this area, there remains a paucity of accurate and reliable data in literature. This work reviews what is available, including both processed datasets and raw medical images, before providing a comprehensive quantitative description of the environment for biomedical engineers in this and related regions of the body. Computed tomography images from 75 patients, and a blend of different mathematical and computational methods, are used to calculate and define several crucial metrics, including: a typical adult size (abdominal girth) and abdominal shape, location (or depth) of the bowel inside the abdomen, large bowel length, lumen diameter, flexure number and characteristics, volume and anatomical tortuosity. These metrics are reviewed and defined by both gender and body posture, as well as—wherever possible—being spilt into the various anatomical regions of the large bowel. The resulting data can be used to describe a realistic ‘average’ adult large bowel environment and so drive both design specifications and high fidelity test environments

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