Benjamin S. Terry

Preliminary Mechanical Characterization of the Small Bowel for In Vivo Robotic Mobility

In this work we present test methods, devices, and preliminary results for the mechanical characterization of the small bowel for intra luminal robotic mobility. Both active and passive forces that affect mobility are investigated. Four investigative devices and testing methods to characterize the active and passive forces are presented in this work: (1) a novel manometer and a force sensor array that measure force per cm of axial length generated by the migrating motor complex, (2) a biaxial test apparatus and method for characterizing the biomechanical properties of the duodenum, jejunum, and ileum, (3) a novel in vitro device and protocol designed to measure the energy required to overcome the self-adhesivity of the mucosa, and (4) a novel tribometer that measures the in vivo coefficient of friction between the mucus membrane and the robot surface. The four devices are tested on a single porcine model to validate the approach and protocols. Mean force readings per cm of axial length of intestine that occurred over a 15 min interval in vivo were 1.34 ± 0.14 and 1.18 ± 0.22 N cm(-1) in the middle and distal regions, respectively. Based on the biaxial stress/stretch tests, the tissue behaves anisotropically with the circumferential direction being more compliant than the axial direction. The mean work per unit area for mucoseparation of the small bowel is 0.08 ± 0.03 mJ cm(-2). The total energy to overcome mucoadhesion over the entire length of the porcine small bowel is approximately 0.55 J. The mean in vivo coefficient of friction (COF) of a curved 6.97 cm(2) polycarbonate sled on live mucosa traveling at 1 mm s(-1) is 0.016 ± 0.002. This is slightly lower than the COF on excised tissue, given the same input parameters. We have initiated a comprehensive program and suite of test devices and protocols for mechanically characterizing the small bowel for in vivo mobility. Results show that each of the four protocols and associated test devices has successfully gathered preliminary data to confirm the validity of our test approach.

Single-Port-Access Surgery with a Novel Magnet Camera System

In this paper, we designed, built, and tested a novel single-port access laparoscopic surgery (SPA) specific camera system. This device (magnet camera) integrates a light source and video camera into a small, inexpensive, portable package that does not compete for space with the surgical tools during SPA. The device is inserted through a 26-mm incision in the umbilicus, followed by the SPA port, which is used to maintain an insufflation seal and support the insertion of additional tools. The camera, now in vivo, remains separate from the SPA port, thereby removing the need for a dedicated laparoscope, and, thus, allowing for an overall reduction in SPA port size or the use of a third tool through the insertion port regularly reserved for the traditional laparoscope. The SPA camera is mounted to the abdominal ceiling using one of the two methods: fixation to the SPA port through the use of a rigid ring and cantilever bar, or by an external magnetic handle. The purpose of the magnet camera system is to improve SPA by: 1) eliminating the laparoscope SPA channel; 2) increasing the field of view through enhanced camera system mobility; and 3) reducing interference between the camera system and the surgical tools at the port, both in vivo and ex vivo.

Evaluation of Peritoneal Microbubble Oxygenation Therapy in a Rabbit Model of Hypoxemia

Alternative extrapulmonary oxygenation technologies are needed to treat patients suffering from severe hypoxemia refractory to mechanical ventilation. We previously demonstrated that peritoneal microbubble oxygenation (PMO), in which phospholipid-coated oxygen microbubbles (OMBs) are delivered into the peritoneal cavity, can successfully oxygenate rats suffering from a right pneumothorax. This study addressed the need to scale up the procedure to a larger animal with a splanchnic cardiac output similar to humans. Our results show that PMO therapy can double the survival time of rabbits experiencing complete tracheal occlusion from 6.6 ± 0.6 min for the saline controls to 12.2 ± 3.0 min for the bolus PMO-treated cohort. Additionally, we designed and tested a new peritoneal delivery system to circulate OMBs through the peritoneal cavity. Circulation achieved a similar survival benefit to bolus delivery under these conditions. Overall, these results support the feasibility of the PMO technology to provide extrapulmonary ventilation for rescue of severely hypoxic patients.

An Integrated Port Camera and Display System for Laparoscopy

In this paper, we built and tested the port camera, a novel, inexpensive, portable, and battery-powered laparoscopic tool that integrates the components of a vision system with a cannula port. This new device 1) minimizes the invasiveness of laparoscopic surgery by combining a camera port and tool port; 2) reduces the cost of laparoscopic vision systems by integrating an inexpensive CMOS sensor and LED light source; and 3) enhances laparoscopic surgical procedures by mechanically coupling the camera, tool port, and liquid crystal display (LCD) screen to provide an on-patient visual display. The port camera video system was compared to two laparoscopic video systems: a standard resolution unit from Karl Storz (model 22220130) and a high definition unit from Stryker (model 1188HD). Brightness, contrast, hue, colorfulness, and sharpness were compared. The port camera video is superior to the Storz scope and approximately equivalent to the Stryker scope. An ex vivo study was conducted to measure the operative performance of the port camera. The results suggest that simulated tissue identification and biopsy acquisition with the port camera is as efficient as with a traditional laparoscopic system. The port camera was successfully used by a laparoscopic surgeon for exploratory surgery and liver biopsy during a porcine surgery, demonstrating initial surgical feasibility.

Characterization and Experimental Results of a Novel Sensor for Measuring the Contact Force From Myenteric Contractions

The intraluminal pressures and traction forces associated with the migrating motor complex are well understood; however, the contact forces directly exerted by the bowel wall on a solid, or near solid, bolus have not previously been measured. Quantifying contact forces is an important component to understanding the net force experienced by an in vivo robotic capsule endoscope. In this paper, we develop a novel sensor, the migrating motor complex force sensor (MFS), for measuring the contact force generated by the contracting myenteron of the small intestine. The MFS consists of a perfused manometer connected to four torus-shaped balloons custom formed of natural latex rubber and embedded with temperature and pressure sensors. Force exerted on the balloon causes sensor pressure change. In vivo, the MFS measures the magnitude and axial location of contact pressure exerted by the myenteron. The device is tested in vivo in a live porcine model on the middle small bowel. The mean total force per centimeter of axial length of intestine that occurred over a 16-min interval in vivo was 1.04 N·cm-1 in the middle region of the small intestine; the measured force is in the range of theoretical values.

Single Port Access Surgery With a Novel Port Camera System

In this work, the authors designed, built, and tested a novel port camera system for single port access (SPA) laparoscopic surgery. This SPA Port Camera device integrates the monitor, laparoscopic camera, and light source into an inexpensive, portable cannula port. The device uses a 2-channel SPA port inserted through an umbilical incision, similar to traditional SPA. After insertion into a channel, the device deploys a small camera module and LED lamp in vivo. An integrated, on-patient LCD provides the view of the surgical site. The design intent of the port camera is to enhance SPA by (a) reducing the size of the SPA port through the elimination of the dedicated laparoscope channel; (b) reducing equipment cost by integrating an inexpensive CMOS sensor and LED lamp at the port tip; (c) eliminating the need for an assistant who operates the laparoscope; and (d) mechanically coupling the camera, tool port, and on-patient LCD screen. The effectiveness of the device was evaluated by comparing the video performance with a leading industry laparoscope and by performing a user evaluation study and live porcine surgery with the device. Effectiveness of the device was mixed. Overall video system performance of the device is better than an industry standard high-definition laparoscope, implying that significant cost savings over a traditional system are possible. Participant study results suggest that simulated laparoscopic tasks are as efficient with the SPA Port Camera as they are with a typical SPA configuration. However, live surgery revealed several shortcomings of the SPA Port Camera.

Superhydrophobic metallic surfaces functionalized via femtosecond laser surface processing for long term air film retention when submerged in liquid

Femtosecond laser surface processing (FLSP) is a powerful technique used to create self-organized microstructures with nanoscale features on metallic surfaces. By combining FLSP surface texturing with surface chemistry changes, either induced by the femtosecond laser during processing or introduced through post processing techniques, the wetting properties of metals can be altered. In this work, FLSP is demonstrated as a technique to create superhydrophobic surfaces on grade 2 titanium and 304 stainless steel that can retain an air film (plastron) between the surface and a surrounding liquid when completely submerged. It is shown that the plastron lifetime when submerged in distilled water or synthetic stomach acid is critically dependent on the specific degree of surface micro- and nano-roughness, which can be tuned by controlling various FLSP parameters. The longest plastron lifetime was on a 304 stainless steel sample that was submerged in distilled water and maintained a plastron for 41 days, the length of time of the study, with no signs of degradation. Also demonstrated for the first time is the precise control of pulse fluence and pulse count to produce three unique classes of surface micron/nano-structuring on titanium.

Intestinal biomechanics simulator for robotic capsule endoscope validation

Abstract This work describes the development and validation of a novel device which simulates important forces experienced by Robotic Capsule Endoscopes (RCE) in vivo in the small intestine. The purpose of the device is to expedite and lower the cost of RCE development. Currently, there is no accurate in vitro test method nor apparatus to validate new RCE designs; therefore, RCEs are tested in vivo at a cost of ∼

A preconditioning protocol and biaxial mechanical measurement of the small intestine

1400 per swine test. The authors have developed an in vitro RCE testing device which generates two peristaltic waves to accurately simulate the two biomechanical actions of the human small intestine that are most relevant to RCE locomotion: traction force and contact force. The device was successfully calibrated to match human physiological ranges for traction force (4–40 gf), contact force (80–500 gf) and peristaltic wave propagation speed (0.08–2 cm s−1) for a common RCE capsule geometry of 3.5 cm length and 1.5 cm diameter.

Work in progress: Gender impacts of relevant robotics curricula on high school students' engineering attitudes and interest

Understanding the biomechanical properties of the small intestine is necessary for developing in vivo mobility systems for miniature robots. In this work, we have experimentally determined preconditioning parameters and then performed in-plane biaxial biomechanical characterisation of small intestinal tissue. Excised tissue samples underwent uniaxial tension tests for two physiological Piola-stress values and multiple cycles. The percent change in the length of the tissue reached equilibrium after approximately 13 preconditioning cycles for both loading values. The mechanical behaviour of the tissue did not appear to be affected by the loading values. Thirty-three tissue samples from the proximal, middle, and distal regions of the small intestine of three pigs underwent preconditioning and subsequent in-plane biaxial biomechanical characterisation. The mean moduli for all samples in the low and high modulus regions were, respectively, 307.25 ± 29.67 kPa and 2,211.72 ± 316.88 kPa along the longitudinal dir...