Autonomous robotic laparoscopic surgery for intestinal anastomosis.

Autonomous robotic surgery has the potential to provide efficacy, safety, and consistency independent of individual surgeon's skill and experience. Autonomous anastomosis is a challenging soft-tissue surgery task because it requires intricate imaging, tissue tracking, and surgical planning techniques, as well as a precise execution via highly adaptable control strategies often in unstructured and deformable environments. In the laparoscopic setting, such surgeries are even more challenging because of the need for high maneuverability and repeatability under motion and vision constraints. Here we describe an enhanced autonomous strategy for laparoscopic soft tissue surgery and demonstrate robotic laparoscopic small bowel anastomosis in phantom and in vivo intestinal tissues. This enhanced autonomous strategy allows the operator to select among autonomously generated surgical plans and the robot executes a wide range of tasks independently. We then use our enhanced autonomous strategy to perform in vivo autonomous robotic laparoscopic surgery for intestinal anastomosis on porcine models over a 1-week survival period. We compared the anastomosis quality criteria-including needle placement corrections, suture spacing, suture bite size, completion time, lumen patency, and leak pressure-of the developed autonomous system, manual laparoscopic surgery, and robot-assisted surgery (RAS). Data from a phantom model indicate that our system outperforms expert surgeons' manual technique and RAS technique in terms of consistency and accuracy. This was also replicated in the in vivo model. These results demonstrate that surgical robots exhibiting high levels of autonomy have the potential to improve consistency, patient outcomes, and access to a standard surgical technique.

A Confidence-Based Supervised-Autonomous Control Strategy for Robotic Vaginal Cuff Closure.

Autonomous robotic suturing has the potential to improve surgery outcomes by leveraging accuracy, repeatability, and consistency compared to manual operations. However, achieving full autonomy in complex surgical environments is not practical and human supervision is required to guarantee safety. In this paper, we develop a confidence-based supervised autonomous suturing method to perform robotic suturing tasks via both Smart Tissue Autonomous Robot (STAR) and surgeon collaboratively with the highest possible degree of autonomy. Via the proposed method, STAR performs autonomous suturing when highly confident and otherwise asks the operator for possible assistance in suture positioning adjustments. We evaluate the accuracy of our proposed control method via robotic suturing tests on synthetic vaginal cuff tissues and compare them to the results of vaginal cuff closures performed by an experienced surgeon. Our test results indicate that by using the proposed confidence-based method, STAR can predict the success of pure autonomous suture placement with an accuracy of 94.74%. Moreover, via an additional 25% human intervention, STAR can achieve a 98.1% suture placement accuracy compared to an 85.4% accuracy of completely autonomous robotic suturing. Finally, our experiment results indicate that STAR using the proposed method achieves 1.6 times better consistency in suture spacing and 1.8 times better consistency in suture bite sizes than the manual results.

A Novel Wax Based Piezo Actuator for Autonomous Deep Anterior Lamellar Keratoplasty (Piezo-DALK).

This paper reports the design and evaluation of a novel piezo based actuator for needle drive in autonomous Deep Anterior Lamellar Keratoplasty (piezo-DALK). The actuator weighs less than 8g and is 20mm × 20mm × 10.5mm in size, making it ideal for eye-mounted applications. Mean open loop positional deviation was 1.17 ± 3.15um, and system repeatability and accuracy were 17.16um and 18.33um, respectively. Stall force was found to vary linearly with the cooling cycle and the actuator achieved a maximum drive force of 3.98N. When simulating the DALK procedure in synthetic corneal tissue, the piezo-DALK achieved a penetration depth of 643.56um which was equivalent to 92.1% of the total corneal thickness. This correlated closely with our desired depth of 90% ± 5% and took 2.5 hours to achieve. This work represents the first eye mountable actuator capable of "Big Bubble" needle drive for autonomous DALK procedures.

Semi-autonomous Robotic Anastomoses of Vaginal Cuffs Using Marker Enhanced 3D Imaging and Path Planning.

Autonomous robotic anastomosis has the potential to improve surgical outcomes by performing more consistent suture spacing and bite size compared to manual anastomosis. However, due to soft tissue's irregular shape and unpredictable deformation, performing autonomous robotic anastomosis without continuous tissue detection and three-dimensional path planning strategies remains a challenging task. In this paper, we present a novel three-dimensional path planning algorithm for Smart Tissue Autonomous Robot (STAR) to enable semi-autonomous robotic anastomosis on deformable tissue. The algorithm incorporates (i) continuous detection of 3D near infrared (NIR) markers manually placed on deformable tissue before the procedure, (ii) generating a uniform and consistent suture placement plan using 3D path planning methods based on the locations of the NIR markers, and (iii) updating the remaining suture plan after each completed stitch using a non-rigid registration technique to account for tissue deformation during anastomosis. We evaluate the path planning algorithm for accuracy and consistency by comparing the anastomosis of synthetic vaginal cuff tissue completed by STAR and a surgeon. Our test results indicate that STAR using the proposed method achieves 2.6 times better consistency in suture spacing and 2.4 times better consistency in suture bite sizes than the manual anastomosis.

Autonomous Laparoscopic Robotic Suturing with a Novel Actuated Suturing Tool and 3D Endoscope.

Compared to open surgical techniques, laparoscopic surgical methods aim to reduce the collateral tissue damage and hence decrease the patient recovery time. However, constraints imposed by the laparoscopic surgery, i.e. the operation of surgical tools in limited spaces, turn simple surgical tasks such as suturing into time-consuming and inconsistent tasks for surgeons. In this paper, we develop an autonomous laparoscopic robotic suturing system. More specific, we expand our smart tissue anastomosis robot (STAR) by developing i) a new 3D imaging endoscope, ii) a novel actuated laparoscopic suturing tool, and iii) a suture planning strategy for the autonomous suturing. We experimentally test the accuracy and consistency of our developed system and compare it to sutures performed manually by surgeons. Our test results on suture pads indicate that STAR can reach 2.9 times better consistency in suture spacing compared to manual method and also eliminate suture repositioning and adjustments. Moreover, the consistency of suture bite sizes obtained by STAR matches with those obtained by manual suturing.

Investigation of gold-coated bare fiber probe for in situ intra-vitreous coherence domain optical imaging and sensing.

We have investigated the usage of gold-plated bare fiber probes for in situ imaging of retinal layers and surrounding ocular tissues using time-domain common-path optical coherence tomography. The fabricated intra-vitreous gold-plated micro-fiber probe can be fully integrated with surgical tools working in close proximity to the tissue to provide subsurface images having a self-contained reference plane independent to the Fresnel reflection between the distal end of the probe and the following medium for achieving reference in typical common-path optical coherence tomography. We have fully characterized the probe in an aqueous medium equivalent to the vitreous humor in the eye and were able to differentiate various functional retinal tissue layers whose thickness is larger than the system's resolution.

Common path optical coherence tomography with fibre bundle probe.

A simple common path optical coherence tomography using a fibre optic bundle as a probe is demonstrated experimentally. The mechanical lateral scans are accomplished outside the specimen, proximal entrance of the fibre bundle, which eliminated the need for moving parts in the distal end of the probe. This feature allows the probe to be made submillimetre in size and easily integrated into surgical tools for intraoperative imaging. The axial and lateral resolutions of the system, and preliminary images of phantom samples, are reported.

Ultrabroad-bandwidth electro-optic modulator based on a cascaded Bragg grating.

It is shown that the bandwidth of a traveling-wave electro-optical modulator can be greatly increased by matching of the group velocities of the optical and rf waves in the waveguides with cascaded Bragg gratings. A LiNbO>(3) Mach-Zehnder modulator with 1-V half-wave voltage and a bandwidth in excess of 100 GHz is proposed and its performance evaluated.

Demonstration of microwave frequency shifting by use of a highly chirped mode-locked fiber laser.

We report an experimental demonstration of a photonic microwave shifter using a highly chirped mode-locked fiber laser. The system is based on dispersive compression or expansion of highly chirped optical pulses that are amplitude modulated by the microwave signal. Using this technique, we demonstrated frequency shifting of a microwave signal from 10 GHz down to 5 GHz and up to 25 GHz.

Demonstration of supercontinuum generation in a long-cavity fiber ring laser.

We demonstrate generation of supercontinuum pulses directly from a passively mode-locked long-cavity fiber ring laser. The laser output exhibited a blueshifted spectrum extending from 1350 to 1550 nm with an average output power greater than 60 mW.

Backward second-harmonic generation in periodically poled bulk LiNbO(3).

We experimentally demonstrate backward second-harmonic generation in periodically poled LiNbO(3) with a 3.3- microm domain period. We observed higher-order phase matching near 1490, 1600, and 1700 nm (fundamental) for the 19th, 18th, and 17th orders, respectively, with a maximum conversion efficiency of 0.02%.

Grating sensor array demodulation by use of a passively mode-locked fiber laser.

A fiber Bragg grating sensor array is interrogated by use of a passively mode-locked fiber laser source. A novel demodulation scheme that uses highly dispersive fiber to convert the grating wavelength shift to a temporal shift in the arrival time of the reflected pulses is demonstrated. The source bandwidth of >85 nm permits interrogation of many-grating arrays, and the demodulation technique permits fast sensing of large strains.

One-dimensional spatial soliton dragging, trapping, and all-optical switching in AlGaAs waveguides.

We report the dragging and mutual trapping of two initially overlapped, orthogonally polarized, onedimensional spatial solitons in an AlGaAs slab waveguide. Using this effect, we realized an all-optical switch that had an on/off switching contrast of ~2.5:1. The contrast of the switch increased to 4:1 when a soliton was used to drag a nonsoliton, weak beam.

Weak-beam trapping by bright spatial solitons in AlGaAs planar waveguides.

We demonstrate experimentally the trapping and spatial wave breaking of weak signal beams by orthogonally polarized bright spatial solitons. Experiments were performed in an AlGaAs planar waveguide excited at a wavelength of 1.55 microm.

Integrated ultrafast saturable absorber.

An ultrafast saturable absorber was demonstrated experimentally in AlGaAs, operated with a photon energy below half the band gap, near 1555 nm. Both the saturation intensity and the linear transmission can be independently designed in the structure. The device is based on spatial soliton emission from a tapered channel waveguide with a corresponding increase in transmission of 50%. The experimental data compare favorably with numerically simulated results.