Soo Jay Phee

Electrical conductivity of thermoresponsive shape-memory polymer with embedded micron sized Ni powder chains

The electrical resistivity of a thermoresponsive polyurethane shape-memory polymer (SMP) filled with micron sized Ni powders is investigated in this letter. We show that, by forming conductive Ni chains under a weak static magnetic field (0.03T), the electrical conductivity of the SMP composite in the chain direction can be improved significantly, which makes it more suitable for Joule heat induced shape recovery. In addition, Ni chains reinforce the SMP significantly but their influence on the glass transition temperature is about the same as that of the randomly distributed Ni powders.

Robotic system for no-scar gastrointestinal surgery.

Flexible endoscopy allows diagnostic and therapeutic interventions on the gastrointestinal (GI) tract. Simple procedures can be performed endoscopically using currently available tools. More advanced endoscopic surgical interventions are much desired and anticipated, yet they await improvements in instrumentation.

Master and slave transluminal endoscopic robot (MASTER) for natural Orifice Transluminal Endoscopic Surgery (NOTES)

Although the flexible endoscopy has been widely used in the medical field for many years, there is still great potential in improving the endoscopists capability to perform therapeutic tasks. Tentatively, tools for the flexible endoscope have poor maneuverability and limited Degree Of Freedom (DOF). In this paper, we propose a surgical robotic system MASTER (Master And Slave Transluminal Endoscopic Robot). MASTER is a dexterous and flexible master-slave device which can be used in tandem with a conventional flexible endoscope. Using this robotic system, ESD (Endoscopic Submucosal Dissection) and NOTES (Natural Orifice Transluminal Endoscopic Surgery) have been conducted on in vivo and ex vivo animal trials with promising results.

Endoscopic submucosal dissection of gastric lesions by using a Master and Slave Transluminal Endoscopic Robot (MASTER)

BACKGROUND Performing endoscopic submucosal dissection (ESD) by using standard endoscopy platforms is technically challenging because of the equipments lack of dexterity. OBJECTIVE To explore the feasibility of using the Master and Slave Transluminal Endoscopic Robot (MASTER), a novel robotics-enhanced endosurgical system, to perform ESD. DESIGN ESD was performed on simulated gastric lesions in 5 Erlangen porcine stomach models (ex vivo) and 5 live pigs (in vivo). Performance of ESD by using the MASTER was compared with that using the insulation-tipped (IT) diathermic knife. SETTING SMART Laboratory, Advance Surgical Training Centre, National University Hospital, Singapore. SUBJECTS Five Erlangen porcine stomach models and 5 pigs, 5 to 7 months old, each weighing about 35 kg. INTERVENTIONS ESD. MAIN OUTCOME MEASUREMENTS Lesion resection time, grasper and hook efficacy grade, completeness of resection, and presence of procedure-related perforation. RESULTS In the Erlangen stomach models, 15 simulated lesions from the cardia, antrum, and body were removed en bloc (mean dimension, 37.4 x 26.5 mm) by electrocautery excision using the MASTER. The mean ESD time was 23.9 minutes (range 7-48 minutes). There was no difference in the dissection times of lesions at different locations (P = .449). In the live pigs, the MASTER took a mean of 16.2 minutes (range 3-29 minutes) to complete the ESD of 5 gastric lesions, whereas the IT diathermic knife took 18.6 minutes (range 9-34 minutes). There was no significant difference in the times taken (P = .708). All lesions were excised en bloc; the mean dimensions of lesions resected by the MASTER and the IT diathermic knife were 37.2 x 30.1 mm and 32.78 x 25.6 mm, respectively. The MASTER exhibited good grasping and cutting efficiency throughout. Surgical maneuvers were achieved with ease and precision. There was no incidence of excessive bleeding or stomach wall perforation. LIMITATIONS Exploratory study with limited sample size. CONCLUSIONS Performing ESD by using the MASTER is feasible.

Natural orifice transgastric endoscopic wedge hepatic resection in an experimental model using an intuitively controlled master and slave transluminal endoscopic robot (MASTER)

BackgroundThe lack of triangulation of standard endoscopic devices limits the degree of freedom for surgical maneuvers during natural orifice transluminal endoscopic surgery (NOTES). This study explored the feasibility of adapting an intuitively controlled master and slave transluminal endoscopic robot (MASTER) the authors developed to facilitate wedge hepatic resection in NOTES.MethodsThe MASTER consists of a master controller, a telesurgical workstation, and a slave manipulator that holds two end-effectors: a grasper, and a monopolar electrocautery hook. The master controller is attached to the wrist and fingers of the operator and connected to the manipulator by electrical and wire cables. Movements of the operator are detected and converted into control signals driving the slave manipulator via a tendon-sheath power transmission mechanism allowing nine degrees of freedom. Using this system, wedge hepatic resection was performed through the transgastric route on two female pigs under general anesthesia. Entry into the peritoneal cavity was via a 10-mm incision made on the anterior wall of the stomach by the electrocautery hook. Wedge hepatic resection was performed using the robotic grasper and hook. Hemostasis was achieved with the electrocautery hook. After the procedure, the resected liver tissue was retrieved through the mouth using the grasper.ResultsUsing the MASTER, transgastric wedge hepatic resection was successfully performed on two pigs with no laparoscopic assistance. The entire procedure took 9.4 min (range, 8.5–10.2 min), with 7.1 min (range, 6–8.2 min) spent on excision of the liver tissue. The robotics-controlled device was able to grasp, retract, and excise the liver specimen successfully in the desired plane.ConclusionThis study demonstrated for the first time that the MASTER could effectively mitigate the technical constraints normally encountered in NOTES procedures. With it, the triangulation of surgical tools and the manipulation of tissue became easy, and wedge hepatic resection could be accomplished successfully without the need for assistance using laparoscopic instruments.

Formation of micro protrusion arrays atop shape memory polymer

Utilizing the significant shape recovery ability (in the order of 100% strain) in shape memory polymers (SMPs), we propose two simple approaches, namely laser heating and indentation, to produce micro-sized protrusion arrays. In the former, after local laser heating a pre-compressed SMP, protrusive bumps can be produced. In the latter, through an indentation-polishing-heating process, various shaped protrusive bumps can be produced. It is to demonstrate that indentation is a more convenient and powerful approach than laser heating, since well controlled, different shaped protrusion arrays can be realized.

Tendon sheath analysis for estimation of distal end force and elongation for sensorless distal end

Tendon sheath actuation can be found in many applications, particularly in robotic hand and surgical robots. Due to friction between the tendon and sheath, many undesirable characteristic such as backlash, hysteresis and non-linearity are present. It is desirable to know the end effector force and elongation of the tendon to control the system effectively, but it is not always feasible to fix sensors at the end effector. A method to estimate the end effector parameters using only a force and position sensor at the proximal site is given. An analytical study is presented and experiments are reported to support the result, showing a max full scale error of approximately 7%. This result is achieved if the shape of the sheath remains the same and buckling is negligible. The results presented in this study could contribute towards haptic development in robotics surgery.

Design of a master and slave transluminal endoscopic robot for natural orifice transluminal endoscopic surgery

Abstract Natural orifice transluminal endoscopic surgery (NOTES) is an endoscopic surgical intervention technique for treatment within the intraperitoneal cavity, which utilizes natural orifices (i.e. mouth, vagina, anus, etc.) as the entry point. In line with minimally invasive surgery (MIS), NOTES aims to perform surgical procedures without skin incisions, thus eliminating unsightly scars. In this article, a master—slave robotic system is proposed to enable the endoscopist to perform demanding NOTES procedures, which are currently performed by surgeons in an opened or keyhole surgery setting. The robotic system consists of a master console and slave manipulators driven by tendon—sheath actuation. Force prediction at the slave end is also introduced in this article to provide force feedback to the surgeon. Using the developed robotic system, liver wedge resection has been conducted in animal trials with promising results.

Interventional navigation systems for treatment of unresectable liver tumor

Most patients with liver tumors are not candidates for surgical resection. A number of local treatment methods for unresectable liver tumors have recently received considerable interests. The major task of these procedures is accurate needle placement with the aim of complete tumor removal and minimal damage to surrounding normal liver parenchyma. In this article, we review the current status of interventional navigation system (INS) for treatment of unresectable liver tumors in terms of overall workflow, tracking systems, and research development. The conceptual design of INS consists of pre-operative and intra-operative modules. The tracking system falls into three types: optical, electromagnetic, and MR gradient based. The current INS, according to their image modalities, can be classified into four categories: MRI based, CT based, U/S based, and multimodalities based. The article also discusses the future research direction for enhanced performance of INS with real time imaging, high accuracy, high resolution, and friendly user-interface.

The glass transition temperature of polyurethane shape memory polymer reinforced with treated/non-treated attapulgite (playgorskite) clay in dry and?wet conditions

Attapulgite (playgorskite), a kind of nanosized fibrous clay mineral, may provide a simple and cheap alternative to improve the stiffness and actuation stress of shape memory polymers (SMPs). As a first step, in this paper, we investigate the glass transition temperature of a polyurethane SMP reinforced with treated/non-treated attapulgite in wet and dry conditions. In addition to confirming the strong influence of moisture, the results reveal that non-treated clay significantly reduces the glass transition temperature (Tg) of the composites, while the influence of treated clay on Tg is limited. However, for composites mixed with non-treated clay, after drying, the well pre-wetted samples have a much higher Tg than that of the dry ones. A partial detachment mechanism is proposed to explain this interesting phenomenon.