IEEE Robotics & Automation Magazine - June 2017 - 75

efficacy of the device. First, the number of actuating jets was
reduced to three, enabling smaller capsule and tether diameters. The efficiency of the jet actuators was greatly improved,
requiring less water per procedure.
The water distribution system was changed substantially
to provide an inert wetted path and independent, high-resolution control of the jet actuators. A single multilumen catheter
was adopted instead of a bundle of single plastic tubes. Finally,
the platform was redesigned to fit inside a suitcase the size of
an airline carry-on, improving portability. The power consumption of the entire platform was optimized to be easily
adapted to battery operation. These improvements make the
HydroJet well suited as a screening aid to complement flexible
endoscopes in LMICs.

The hydraulic system, the part inside the suitcase, is
designed to precisely regulate flow to each of the capsule jets
and in turn control jet actuation force. Compressed air is used
to pressurize water in a dispensing pressure vessel (Figure 1).
The water is delivered from the vessel to a distribution manifold. Throttle control of the jets is achieved using a set of proportional pinch valves that independently regulate the flow
rate of each jet. These valves use a specialized piston to pinch
the line closed without contacting the water and provide a simple and responsive way to control the flow. Suction is provided
through the multichannel tether into a hygienic receptacle.
Similar to traditional endoscopy, a button can be depressed at
the endoscopist's discretion to trigger the pump and begin suction. In case of suction lumen obstruction, backflow flush, as
in traditional endoscopy, can be performed to clean and clear
the suction port. Two flowmeters (Figure 1) monitor the rate
of fluid flow to and from the stomach to maintain a safe balance (typically around 1.3 L).

Platform Overview
The HydroJet is an endoscopic platform (Figure 1) designed
for UGI cancer screening. The capsule (10-mm diameter by
29-mm length) carries a camera within a hermetically sealed
shell [Figure 2(c)]. The camera, which contains embedded System Design and Fabrication
light-emitting diodes (LEDs) for illumination, is loaded into
the back half of the capsule shell and connects through a Capsule
four-prong snap connector. The front half of the capsule is The capsule components are made from a durable plastic
then attached to restrain the camera and seal the capsule. (Objet Verowhite Plus) via three-dimensional (3-D) printing
The capsule body contains three jet ports, spaced at 120° (Objet Geometries Ltd., Rehovot, Israel, model OBJET 30).
each around the diameter, which serve as actuators when Although this material is not medical grade, it is currently
pressurized water is ejected from the capsule. Jet actuation used due to its low price and availability. When moving forforce is controlled externally by the components in the suit- ward with clinical trials, a biocompatible material, such as
case, resulting in a mechanically simple capsule design. The polyether-ether-ketone, will be used for capsule fabrication.
HydroJet is designed with disposable and reusable compo- Suction is provided by a dedicated port offboard the capsule,
nents [see Figure 2(b)]. After completion of a cancer screen- eliminating the need for additional suction ports on the caping procedure, the HydroJet outer shell and tether are sule. The reusable inner core [Figure 2(b)] contains the camdiscarded and the capsule's camera (preserved from patient era module (Aidevision, Shenzhen, China, model AD-3915);
contact by the outer shell) is reclaimed
without reprocessing.
The capsule and tether form a
Camera Module
system that is similar to traditional
(Reusable)
endoscopes. Through selectively
Electrical
throttling each of the water jets, the
Connector
HydroJet can autonomously pan the
capsule with two degrees of freedom
Camera Cover
(2 DoF). Linear control of the cap(Disposable)
sule is accomplished by pushing/
pulling the tether. Adjustment of the
(b)
tether pivot length can be varied as
needed to visualize the entire esophMultilumen
agus and stomach. By combining the
Tether (Disposable)
robotic 2 DoF and a manual DoF
given by pushing and pulling the
tether, the HydroJet can achieve
3-DoF motion to explore the gastric
cavity. Suction to remove the excess
(c)
(a)
of water from the stomach is provided through the tether by a dedicated
Figure 2. (a) The HydroJet platform designed to be easily transportable, (b) the HydroJet
line, which does not require an addi- capsule disassembled into disposable and reusable components, and (c) the HydroJet
capsule.
tional port on the capsule.
June 2017

IEEE ROBOTICS & AUTOMATION MAGAZINE

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