PRIORITY CLAIM

This application claims the priority benefit of U.S. Provisional Patent Application Serial No. 63/404,980, filed September 9, 2022, the disclosure of which is incorporated herein by reference in its entirety.

GOVERNMENT INTEREST

This invention was made with government support under R15 EB028576 awarded by the National Institutes of Health (NIH). The government has certain rights in the invention.

TECHNICAL FIELD

The subject matter disclosed herein relates generally to end effector assemblies for surgical instruments and methods for using the end effector assemblies and surgical instruments.

BACKGROUND

Energy-based, ultrasonic (US) and radiofrequency (RF) devices commonly provide rapid sealing and hemostasis of vascular tissues during surgery. These devices are used in about 80% of the 15 million laparoscopic surgical procedures performed globally each year. As an alternative, infrared (IR) laser sealing and bisection of vascular tissues has recently been reported in the laboratory. Potential advantages of IR laser devices include: (1 ) rapid optical sealing and cutting of vascular tissues without the need for a separate deployable mechanical blade to bisect tissue seals, (2) less thermal spread for potential use near sensitive tissue structures (e.g. nerves), (3) stronger vessel seals as measured by burst pressures (BP) in the laboratory, and (4) lower device jaw temperatures for a safer profile (e.g. to avoid thermal damage to adjacent soft tissues through inadvertent devicetissue contact) and to enable shorter device cooling times in between successive applications for reduced operating room times with associated cost savings.

A major design limitation is the size constraints of the standard Maryland style jaw and the 5-mm-outer-diameter (OD) shaft of laparoscopic energy-based surgical devices. The bottom fixed jaw design will not only need to reflect the IR laser beam at a 90° angle, but also to convert the circular spatial beam profile into a linear beam, to create a uniform lengthwise seal across the width of the blood vessel, all within the limited space of the laparoscopic instrument. In general, the top jaw, with a pivoting hinge, serves to open and close for grasping vessels and provides tissue compression to facilitate thermal sealing.

SUMMARY

This document describes surgical instruments, end effectors for surgical instruments, and methods of using surgical instruments. An example end effector assembly includes a first jaw member and a second jaw member. The first jaw member includes: a transparent tissue contacting surface; at least one transparent viewing portion; a fluid-tight cavity to keep bodily fluids out, configured to receive an optical fiber; and a reflector configured to reflect a substantial portion of light from the optical fiber towards the transparent tissue contacting surface. The second jaw member is configured to move towards the transparent tissue contacting surface of the first jaw member.

Although some of the aspects of the subject matter disclosed herein have been stated hereinabove, and which are achieved in whole or in part by the presently disclosed subject matter, other aspects will become evident as the description proceeds when taken in connection with the accompanying drawings as best described hereinbelow.

BRIEF DESCRIPTION OF DRAWINGS

Figure 1A shows an example surgical instrument;

Figure 1 B illustrates the end effector assembly;

Figure 1 C illustrates that the second jaw member is configured to move towards the transparent tissue contacting surface of the first jaw member;

Figure 1 D is a cross-sectional view of a first example configuration of the first jaw member;

Figure 1 E is a cross-sectional view of a second example configuration of the first jaw member;

Figure 1 F is a flow diagram of an example method for using the surgical instrument.

Figures 2A - 2B illustrate an example system for testing an example implementation of the end effector;

Figure 3 is a graph of irradiance versus spatial position (mm) that illustrates the initial laser beam profile exiting the optical fiber;

Figure 4 shows the spatial distribution of the laser beam exiting the optical chamber for quartz and sapphire;

Figure 5 illustrates Monte Carlo simulations showing light transport through the quartz chamber and into the tissue layer;

Figure 6 shows images of the quartz chamber design and thermal simulation results at several time points; Figure 7 shows simulated results for the temperature-time response on the external surface of the quartz chamber;

Figures 8A - 8B show representative temperature-time data for TCs placed on the external and internal surfaces of the quartz and sapphire chambers;

Figure 9 shows a scatter plot of BPs as a function of vessel diameter for quartz and sapphire chambers; and

Figure 10 shows representative blood vessels after laser treatment, for quartz and sapphire chambers.

DETAILED DESCRIPTION

There are several technical limitations of systems using a reciprocating, side-firing, optical fiber to produce a uniform linear beam profile within a standard Maryland laparoscopic jaw design. First, the non-transparent, metallic jaws of standard laparoscopic devices and the corresponding limited surgical field-of-view may make accurate positioning and centering of tissues within the jaws difficult to achieve in clinical practice.

Second, a wide range of blood vessel diameters (2-6 mm), are typically treated during surgery with energy-based devices. Therefore, a fixed scan length for the reciprocating fiber is not practical. A short scan length may not provide a full-thickness seal in larger vessels, leading to incomplete and failed seals without hemostatic closure. A long scan length may result in inefficient deposition of the optical energy into the vessel and excessive laser energy being transmitted around the edges of a small vessel, in turn resulting in higher device jaw temperatures and longer cooling times in between applications than acceptable during surgery.

Disclosed herein are end effector assemblies for surgical instruments. The end effector assemblies have a transparent viewing portion that may enable improved visibility for positioning vascular tissues within the laparoscopic device jaws and customization of the reciprocating fiber scan length to match the compressed width of the blood vessels.

Figure 1A shows an example surgical instrument 100. The surgical instrument includes a handle 102, an elongated body 104 extending from the handle 102, and an end effector assembly 106 secured to a distal portion of the elongated body 104. The handle 102 includes one or more control interfaces configured to manipulate the end effector assembly 106. The control interfaces can include, for example, a movable handle, a trigger, a switch, and a button. The handle 102 can include a wheel or rotation control configured to rotate the elongated body 104, and the end effector assembly 106, relative to the handle 102.

Figure 1 B illustrates the end effector assembly 106 in detail. The end effector assembly 106 comprises a first jaw member 108 and a second jaw member 110. The first jaw member 108 includes a transparent tissue contacting surface 112 and at least one transparent tissue viewing portion 114. The first jaw member 108 includes a fluid-tight cavity 116 to keep fluid out and configured to receive an optical fiber 118. In some examples, the fluid-tight cavity 116 is sufficiently sealed to be air-tight.

The transparent tissue contacting surface 112 and the transparent tissue viewing portion 114 can be made, for example, from quartz, sapphire, or any other appropriate material. The term “transparent” is used in this document to refer to material that substantially transmits light in the visible range of 400-700 nm for the surgeon to see through the device and in the infrared range at a wavelength suitable for sealing or cutting tissue or both. For example, the optical fiber 118 may transmit light having a wavelength in a range of about 800 nm to about 2500 nm. The first jaw member 108 includes a reflector 120 configured to reflect a substantial portion of light from the optical fiber 118 towards the transparent tissue contacting surface 112. In some examples, the reflector 120 comprises a side-firing fiber tip of the optical fiber 118, e.g., created by an angled tip. In some examples, a small mirror or other optical element is positioned within the cavity 116 to direct light exiting the optical fiber 118 towards the tissue contacting surface 112.

The first jaw member 108 can include a first opaque plug 122 at a distal end of the first jaw member 108. The first jaw member 108 can include a second opaque plug 124 at a proximal end of the first jaw member 108. The opaque plugs 122 and 124 can be useful, for example, to prevent stray light from exiting the first jaw member 108, and to close the distal tips of the optical chambers to provide fluid-tight closure.

The first jaw member can include one or more mounts 132 configured to prevent the optical fiber 118 from rotating within the fluid-tight cavity 116. The mounts 132 can be useful, for example, where the reflector 120 is an angled fiber tip that should remain oriented towards the tissue contacting surface 112.

Figure 1 C illustrates that the second jaw member 110 is configured to move towards the transparent tissue contacting surface 112 of the first jaw member 108. The second jaw member 110 can include a transparent tissue contacting portion 126 opposing the transparent tissue contacting portion 112 of the first jaw member 108 and a transparent viewing portion 128. For example, the second jaw member 110 can be coupled with the first jaw member 108 by a hinge, allowing an operator to control the second jaw member 110 to move towards the first jaw member 108 to clamp tissue 130 between the first jaw member 108 and the second jaw member 110 In some examples, the tissue contacting surface 112 of the first jaw member 108 or the tissue contacting surface 126 of the second jaw member 110 or both includes features to prevent tissue 130 grasped or clamped between the first and second jaw members 108 and 110 from moving relative to the first and second jaw members 108 and 110. For example, one or more of the tissue contacting surfaces may be textured to grasp tissue. Additionally or alternatively, one or more of the tissue contacting surfaces 112 and 126 may include ridges, ribs, or other features extending towards the opposite jaw member to secure tissue between the first and second jaw members.

Figure 1 D is a cross-sectional view of a first example configuration of the first jaw member 108. The first jaw member 108 comprises a substantially rectangular tube having four sides 112, 114, 132, and 134. The transparent tissue contacting surface 112 is a first side and the transparent viewing portion is a second side opposite the first side. The other sides 132 and 134 can also be transparent (or include transparent portions) to further allow for viewing through the first jaw member 108.

Figure 1 E is a cross-sectional view of a second example configuration of the first jaw member 108. The first jaw member 108 comprises a tube having a substantially circular cross-section. The entire tube may be transparent. A first arc segment of the tube is considered the transparent tissue contacting surface 112 and a second arc segment of the tube is considered the transparent viewing portion 114.

The surgical instrument 100 can be used for laparoscopic surgery. Figure 1 F is a flow diagram of an example method 150 for using the surgical instrument 100 The method 150 includes positioning the end effector within a patient (152), e.g., using one or more control interfaces on the surgical instrument. The method 150 includes moving the second jaw member towards the first jaw member to clamp tissue between the first jaw member and the second jaw member (154).

The method 150 includes providing light into the optical fiber of the end effector assembly (156). Light can be provided from any appropriate light source, e.g., lasers, light emitting diodes (LEDs), and lamps. The method 150 includes reflecting a substantial portion of light from the optical fiber towards the transparent tissue contacting surface of the first jaw member (158), for example, using a sidefiring optical fiber tip.

The method 150 includes moving the tip of the optical fiber within the fluid- tight cavity of the first jaw member and thereby cutting or sealing tissue or both (160). For example, a motor controller can be used to move the tip of the optical fiber in a reciprocating manner. The distance moved by the fiber optic tip (scan length) can be controlled based on the width of the compressed tissue clamped, e.g., such that the distance is greater for larger vessels. The size of a vessel can be judged more easily (e.g., by a physician) due to the transparent viewing portion of the end effector.

Figures 2A - 2B illustrate an example system 200 for testing an example implementation of the end effector 202 using quartz and sapphire tubing. Results of the testing are presented below for the purpose of illustration and not limitation.

Optical and thermal characterization of the quartz and sapphire tubing was performed. Infrared laser sealing of porcine renal blood vessels was also conducted to determine whether industry standard destructive vessel burst pressure (BP) measurements in the laboratory are sufficient for potential future surgical application, as judged by BP needing to exceed both systolic (120 mmHg) and hypertensive blood pressure (180 mmHg).

Fresh porcine kidney pairs were acquired and renal arteries were dissected and then stored in physiological saline in a refrigerator prior to use. A similar range of vessel diameters was chosen for the quartz and sapphire treatment groups, for direct comparison. A total of n = 13 blood vessels with a mean, uncompressed diameter of 3.4 ± 0.7 mm, were selected for tests with the quartz chamber, while a total of n = 14 vessels with a diameter of 3.2 ± 0.7 mm, were selected for use with the sapphire chamber (P = 0.41 ).

A 100-Watt, 1470 nm wavelength IR diode laser 204 was used for vessel sealing studies. The laser was operated in continuous-wave (CW) mode with incident power at the tissue surface of 30 W for a short duration of 5 s. Laser power output was calibrated using a meter and detector.

Blood vessel samples were compressed and fixed in place using a 0.5-mm- thick optical window 206 locked in a clamp, to simulate a transparent top jaw. An optical coherence tomography (OCT) system with 8 Fr (2.67-mm-OD) laparoscopic probe provided non-invasive imaging and measurement of the compressed vessel thickness to confirm consistent pressures and for reproducible measurements between samples. The compressed tissue thickness was fixed at 0.4 mm to approximately match the optical penetration depth of IR light in water-rich soft tissues at a wavelength of 1470 nm, and to provide uniform, full-thickness seals.

A low-OH, silica optical fiber 208 with 550-pm-core, 600-pm-cladding, 1040- pm-jacket, and numerical aperture (NA) of 0.22 was used for vessel sealing studies. The proximal fiber tip 208a with high-power, SMA905 connector was attached to the laser 204. The side-firing, distal fiber tip 208b was prepared using a bare fiber polisher, rotated to achieve a 50° angle, and accurate to 0.5°. A value of 90% power reflected was acceptable due to the accuracy of the side angle polish.

The bottom optical chamber 210 comprised quartz or sapphire square tubing with dimensions of 1 .8 x 1 .8 mm ID, 2.7 x 2.7 mm OD, 25 mm length, and 0.45 mm wall thickness. A 3D-printed, black resin plug 212a-b was placed on each end. The proximal end plug 212b had a small hole to allow insertion of the optical fiber 208. The distal end plug 212a also had a small hole to allow insertion of a thermocouple, but otherwise provided fluid-tight closure and absorbed stray light in the forward direction. The fiber 208 was inserted into the quartz/sapphire tubing 210 and clamped in place, leaving 0.6 mm between the side-firing silica fiber tip and the inner walls of the tubing. The distance from fiber tip to vessel wall was measured to be 1.05 mm (air gap of 0.6 mm + quartz/sapphire wall thickness of 0.45 mm).

A micro-controller 214 was programmed to a specific scan length (11 mm) and speed (87 mm/s) for the servo motor 216. The microcontroller 214 was programmed with code to control the motor 216 to sweep back and forth over an angle of 45° with a 2.5 ms delay on either end. The motor 216 used 4.8 V, giving 1.8 kg-cm in stall torque at 0.10 s per 60°. The fiber 208 was threaded through and locked down onto an arm attached to the motor 216. The motor 216 was powered by a battery pack 218, with a circuit board 220 enabling an external on/off switch. The lower jaw comprised steel tubing supporting the quartz or sapphire square tubing. Blood vessels were compressed onto the quartz/sapphire chamber using a glass microscope slide 206, simulating a transparent upper jaw. Burst pressure (BP) measurements were taken. Vessel BP measurements are a standard method for determining vessel seal strength. The setup included a pressure meter, infusion pump, and iris clamp. The vessel lumen was clamped over a cannula attached to the pump. Deionized water was flowed at 100 ml/hr and maximum BP recorded. A successful seal exceeded 360 mmHg, or three times systolic blood pressure (120 mmHg), consistent with industry standards for destructive testing of vessel seals.

A two-tailed student’s t-test was used to determine differences between the quartz and sapphire chamber data groups for the following parameters: vessel diameter, burst pressure, internal peak temperature, external peak temperature, internal cooling time, and external cooling time. A value of P < 0.05 was considered to be statistically significant between data sets.

Computational Simulations

Optical and thermal simulations were performed to further characterize example implementations of the end effector assemblies described in this document. Zemax and Monte Carlo optical simulations were performed.

In the Zemax simulations, quartz and sapphire chambers were designed using identical dimensions to the experiments. A point source was used for simulations. Figure 3 is a graph of irradiance versus spatial position (mm) that illustrates the initial laser beam profile exiting the optical fiber, used for both the quartz and sapphire Zemax simulations.

Figure 4 shows the spatial distribution of the laser beam exiting the chamber for quartz and sapphire. Figure 4 shows ray tracing showing both (left column) beam divergence through the optical chamber and (right column) initial beam profile, for both quartz (top row) and sapphire (bottom row), using Zemax optical software. Note that the quartz chamber had curved edges, due to commercial availability of square quartz tubing, while the sapphire chamber was assembled from four individual optical windows, resulting in straight edges, due to the lack of commercial availability for square sapphire tubing. In general, the end effector assemblies described in this document can have chambers of any appropriate shape, e.g., with curved or straight edges.

The wider output beam profile of quartz (3.2 mm) compared to sapphire (2.5 mm) is responsible for the larger seal zone observed. The larger seal zone (with higher irradiance in center) may enable simultaneous bisection of the vessel with thermal sealing (from lower irradiation at the ends) of both vessel ends, in a one- step process. When using a sapphire chamber with a smaller output beam profile, the seal zone was narrower, which may prohibit simultaneous bisection and sealing of vessels. This simulation result also explains the narrow carbonization zone at the center of the seal using a quartz chamber. The small peaks in the output beam profile for the sapphire tubing are due to the refraction of light rays at the straight corners of the tubing.

Monte Carlo (MC) simulations were also performed (using Zemax software) to determine the amount of light reflected and scattered back into the quartz chamber. Figure 5 illustrates Monte Carlo simulations showing light transport through the quartz chamber and into the tissue layer. A total of 1 million light rays were used in the simulations.

A Henyey-Greenstein bulk scattering model was used. Values for mean free path, transmission fraction (albedo), and anisotropy factor, g, were entered into Zemax for quartz. Mean free path and transmission factor were calculated using the following formulas: Mean free path = 1 / (p _s + p _a ) and Transmission fraction = p _s / (p _a + p _s ). The following optical properties for renal arteries were used, taken from previous literature [6], p _s = 267 cm ^-1 , p _a = 20.4 cm ^-1 , and g = 0.875. Using the formulas above, Mean free path = 0.035 and Transmission fraction = 0.929.

In the computational setup, two detectors (inside and outside the quartz chamber) were strategically positioned to measure power leaving the tissue and power re-entering the chamber, due to both Fresnel reflections and diffuse reflection (back-scattered photons). A 30 W point light source was used for simulations, similar to experiments, and 1 million rays were launched into the tissue. The external detector measured 2.63 W, or 8.7% of input power. The internal detector measured 1.97 W, or 6.6% of input power. These results were consistent with predominantly forward-scattering behavior of tissue that has a high anisotropy factor (g = 0.875). Hence, to replicate experimental conditions in COMSOL simulations for thermal analysis of the quartz chamber, a reflection coefficient of 0.066 (or 6.6%) was employed for the surface.

For the thermal simulations, the heat source in the quartz chamber is provided by the following equation in COMSOL:

Q _o = Total pow

R _c = Reflection Coefficient (based on Wavelength) Exponential decay due to

A _c - Absorption Coefficient absorption

2D Gaussian Distribution

In xy-plane

Heat flux is Q = h(Text - T) where h = heat transfer coefficient of air that depends on initial material temperature (T) and surrounding medium, (e.g. air temperature, Text). A quartz chamber was designed in COMSOL using dimensions similar to experiments. The simulation incorporated a laser (heat source) directed towards the internal bottom surface of the quartz chamber, mimicking conditions encountered in the experimental setup. The laser beam was also visible on the top surface due to reflection from the bottom surface. This enabled tracking of the laser beam movement within the quartz chamber. To replicate the reciprocating motion of the fiber tip within the quartz chamber, the location of the light source was variable only along the y-axis using the interpolation feature in COMSOL, covering a scan length of 11 mm.

A domain point probe was placed on the top surface within the scan length of the light source. This probe effectively replicated the position of the thermocouple used in the experiments to measure the temperature along the scan length of the fiber tip on the top surface. After 5 s, the laser was turned off, but the simulation continued recording surface temperatures of the quartz chamber until body temperature (37°C) was reached. Convective cooling from air played a major role in lowering the quartz chamber’s temperature.

Figure 6 shows images of the quartz chamber design and thermal simulation results at several time points (t = 0, 3.25, 5, and 22 s). In particular, Figure 6 shows COMSOL simulations showing the temperature profile on the external surface of the quartz chamber (with plugs inserted on both ends) at different time points of t = 0 s (start of laser irradiation), t = 3.25 s (during laser irradiation), t = 5 s (after laser de-activated), and t = 22 s (after 17 s of cooling).

Figure 7 shows simulated results for the temperature-time response on the external surface of the quartz chamber. External temperature (in Kelvin) of the quartz chamber as a function of time. Laser is activated at t = 0 s and de-activated at t = 5 s. The highest temperature was 351 K (77.85 °C), with cooling time of 16 s to reach body temperature (37 °C), consistent with experimental results.

The highest temperature was 351 K (77.85 °C), with cooling time of 16 s to reach body temperature (37 °C), again consistent with experimental results. The quartz chamber experienced a sharp temperature decrease after 5 s when the laser was turned off, due to efficient heat transfer between the quartz wall and air, facilitated by the temperature gradient. As the temperature of the quartz wall approached that of ambient air temperature, the rate of heat transfer decreased, due to the reduced temperature difference between the quartz wall and the air.

Figure 7 shows multiple peaks and valleys at specific time intervals. When the sensor and scanned laser beam locations coincided, a temperature peak resulted due to localized thermal accumulation induced by the laser. When the laser beam was further away from the sensor, the temperature decreased. As the sensor recorded the temperature measurement when the laser and sensor are again at the same location, subsequent temperature peaks continue to increase due to thermal buildup from previous laser heating. Furthermore, the absence of peaks and valleys in the data during the cooling phase also suggests that these fluctuations arise from interplay between the sensor and scanned laser during data acquisition.

Experimental Results

Side-firing optical fibers polished at a 50° angle delivered 94% of light sideways at a 90° angle, with 3.7% in opposite direction (-90°) and 2.3% in forward (0°) direction. Total Fresnel reflection losses for the two quartz/air interfaces measured 6%, with 94% of the side-firing light transmitted through the quartz tubing wall. These values are consistent with the refractive index mismatch between quartz at 1470 nm (n _q = 1.445) and air (n _a = 1.0), which yields a reflection loss of 3.3% per a surface, or total of 6.6% for two surfaces.

The maximum temperatures measured on the internal surface of the quartz chamber (45.4 ± 5.8 °C) were significantly lower than on the external surface (73.8 ± 8.4 °C) (P = 2E-4). The maximum temperatures measured on the internal surface of the sapphire chamber (66.1 ± 15.5 °C) were not significantly different than on the external surface of the chamber (72.8 ± 9.8 °C) (P = 0.20). There was also no significant difference between the external temperatures for quartz and sapphire chambers (P = 0.78).

However, the largest difference between the quartz and sapphire chamber studies was found in the cooling times. The cooling times for the external surface of the chamber are of interest, since they determine how long the surgeon must wait in between successive surgical applications of the laparoscopic sealing device, to prevent thermal damage to adjacent tissues through contact with the device. The external surface of the quartz chamber cooled down to body temperature (37 °C) in 13 ± 4 s, while the external surface of the sapphire chamber required twice as long to cool down, at 27 ± 7 s (P = 1 E-6). There was an even larger difference in cooling times for the inside of the quartz and sapphire chambers, 4.2 ± 3.8 s and 40.0 ± 3.8 s, respectively (P = 1 E-18), due to thermal buildup inside the sapphire chamber from higher Fresnel reflection losses at the air/sapphire interface.

Figures 8A - 8B show representative temperature-time data for TCs placed on the external and internal surfaces of the quartz/sapphire chambers. Figures 8A - 8B show representative thermocouple temperature measurements on the internal (Tin) and external (Tout) surfaces of the (Figure 8A) quartz and (Figure 8B) sapphire optical chambers, as a function of time. Vessel sealing studies were performed with an incident laser power of 30 W at the tissue surface and a laser irradiation time of 5 s at a wavelength of 1470 nm.

Blood vessel burst pressures (BP) were measured. For the quartz chamber, vessel BP averaged 883 ± 393 mmHg, with 13/13 vessels (100%) achieving successful BPs above 360 mmHg. For the sapphire chamber, vessel BPs measured 412 ± 330 mmHg, with only 10/14 vessels (64%) sealed successfully. This difference in burst pressures was statistically significant (P = 0.003).

Figure 9 shows a scatter plot of BPs as a function of vessel diameter for quartz and sapphire chambers. The dashed horizontal line shows the industry standard threshold of 360 mmHg (three times systolic blood pressure) for designation of a successful seal. For the quartz chamber, vessel BP averaged 883 ± 393 mmHg, with 13/13 vessels (100%) recording BPs above 360 mmHg. For the sapphire chamber, vessel BPs measured 412 ± 330 mmHg, with 10/14 vessels (64%) sealed.

It is common to observe a wide range in the vessel burst pressures of successful seals during laboratory testing, with all energy-based devices, due in part to differences among samples in vessel diameter, collagen/elastin content, attached fatty tissue layers, and water content.

As vessel diameter increases, the BPs achieved using the quartz chamber trend higher, while BPs for sapphire chamber trend lower. The decreasing trend in BPs for larger vessels treated with the sapphire chamber can be explained by observed incomplete, less than full thickness seals, due to more significant heating on the front surface of the vessel sample. Thermal coagulation of soft tissues is well known to result in dynamic changes in the optical properties of tissues, specifically an increase in light scattering, which in turn results in decreased optical penetration depth and an even steeper temperature gradient with depth. The vessel sealing process for the sapphire chamber may therefore be dominated by thermal conduction from the front surface, rather than uniform deposition of optical energy into the tissue, with this effect enhanced by the higher thermal conductivity for sapphire than quartz, as discussed further below.

Figure 10 shows representative blood vessels after laser treatment, for quartz and sapphire chambers. A relatively uniform and well delineated zone of thermally coagulated tissue is observed on both the front and back surfaces of blood vessels successfully sealed using both the quartz and sapphire optical chambers. However, in the vessels that failed using the sapphire chamber, as determined by low burst pressures (< 360 mmHg), an incomplete thermal coagulation zone is observed on the back side of the vessel, indicating a less than full thickness seal.

Figure 10 includes photographs of the vessels before and after sealing for sapphire and quartz. (A,B,C) A 3.5 mm diameter vessel in its native state, as well as after it was sealed unsuccessfully using the sapphire chamber, showing its front side, and back side, respectively. (D,E) A 3.3 mm diameter vessel, showing its front and back sides, respectively, after a successful seal (BP = 554 mmHg) using the sapphire chamber. (F,G,H) A 3.3 mm diameter vessel in its native state, as well as after it was sealed successfully (BP = 776 mmHg) using the quartz chamber, showing its front side and back side, respectively. All vessels sealed with the quartz chamber were successful. An incomplete zone of the thermal coagulation on the backside of the vessel is observed for the failed seal using the sapphire optical chamber in image (C).

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one having ordinary skill in the art to which the presently disclosed subject matter belongs. Although, any methods, devices, and materials similar or equivalent to those described herein can be used in the practice or testing of the presently disclosed subject matter, representative methods, devices, and materials are now described.

Following long-standing patent law convention, the terms “a”, “an”, and “the” refer to “one or more” when used in this application, including the claims. Thus, for example, reference to "a vial" can include a plurality of such vials, and so forth.

Unless otherwise indicated, all numbers expressing quantities of length, diameter, width, and so forth used in the specification and claims are to be understood as being modified in all instances by the terms “about” or “approximately”. Accordingly, unless indicated to the contrary, the numerical parameters set forth in this specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the presently disclosed subject matter.

As used herein, the terms “about” and “approximately,” when referring to a value or to a length, width, diameter, temperature, time, volume, concentration, percentage, etc., is meant to encompass variations of in some embodiments ±20%, in some embodiments ±10%, in some embodiments ±5%, in some embodiments ±1 %, in some embodiments ±0.5%, and in some embodiments ±0.1 % from the specified amount, as such variations are appropriate for the disclosed apparatuses and devices. As used herein, ranges can be expressed as from “about” one particular value, and/or to “about” another particular value. It is also understood that there are a number of values disclosed herein, and that each value is also herein disclosed as “about” that particular value in addition to the value itself. For example, if the value “10” is disclosed, then “about 10” is also disclosed. It is also understood that each unit between two particular units are also disclosed. For example, if 10 and 15 are disclosed, then 11 , 12, 13, and 14 are also disclosed.

The term “comprising”, which is synonymous with “including” “containing” or “characterized by” is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. “Comprising” is a term of art used in claim language which means that the named elements are essential, but other elements can be added and still form a construct within the scope of the claim.

As used herein, the phrase “consisting of” excludes any element, step, or ingredient not specified in the claim. When the phrase “consists of’ appears in a clause of the body of a claim, rather than immediately following the preamble, it limits only the element set forth in that clause; other elements are not excluded from the claim as a whole.

As used herein, the phrase “consisting essentially of’ limits the scope of a claim to the specified materials or steps, plus those that do not materially affect the basic and novel characteristic(s) of the claimed subject matter.

With respect to the terms “comprising”, “consisting of”, and “consisting essentially of”, where one of these three terms is used herein, the presently disclosed and claimed subject matter can include the use of either of the other two terms. As used herein, the term “and/or” when used in the context of a listing of entities, refers to the entities being present singly or in combination. Thus, for example, the phrase “A, B, C, and/or D” includes A, B, C, and D individually, but also includes any and all combinations and sub-combinations of A, B, C, and D. The presently disclosed subject matter can be embodied in other forms without departure from the spirit and essential characteristics thereof. The embodiments described therefore are to be considered in all respects as illustrative and not restrictive. Although the present subject matter has been described in terms of certain preferred embodiments, other embodiments that are apparent to those of ordinary skill in the art are also within the scope of the present subject matter.