Laparoscopic Semi-Automatic Suturing System Overview Oct 16 2016 by Alex Tegzes

Laparoscopic Suturing System Industrial Design Overview

Prepared by: Aleksandar Tegzes, M.Eng, P.Eng

Date: Oct 16 2016


Prepared by: Aleksandar Tegzes, M.Eng, P.Eng 2 | P a g e

Contents Table of Figures ............................................................................................................................................. 4

Scope ............................................................................................................................................................. 5

Problem to Solve ........................................................................................................................................... 5

Specifications and Assumptions................................................................................................................ 5

Suturing Method ........................................................................................................................................... 6

1. Deploy Stabilizing Augers .................................................................................................................. 6

2. Close the Wound with a Curved Suture Needle ............................................................................... 6

3. Needle Tip Exchange Grasper ........................................................................................................... 7

4. Needle Tip Grasper Retracts Curved Needle Tip .............................................................................. 9

5. Curved Tube is Retracted .................................................................................................................. 9

Curved Tube Needle Handle Controls Overview ........................................................................................ 11

1. Trigger Interlock .............................................................................................................................. 11

2. Stainless Cable with Bicycle Style Pull Anchors............................................................................... 12

Needle Tip Exchange Grasper Controls Overview ...................................................................................... 16

1. Needle Grasper Default State ......................................................................................................... 17

2. Needle Grasper Open State ............................................................................................................ 18

Auger Tissue Stabilizer Controls Overview ................................................................................................. 19

1. Deploying Tissue Augers ................................................................................................................. 19

2. Removing Augers ............................................................................................................................ 20

Manufacturability Overview ....................................................................................................................... 21

Curved Needle Hypodermic Tube ........................................................................................................... 21

Laparoscopic Suture System Main Body ................................................................................................. 22

Needle Tube Torque Spindle................................................................................................................... 22

Curved Needle Tube and Torque Spindle Welded Assembly ................................................................. 23

Curved Needle Tip and Suture Assembly ................................................................................................ 24

Grasping Needle Tip Collet...................................................................................................................... 24

Tissue Stabilizing Auger ........................................................................................................................... 27

Final Discussions ......................................................................................................................................... 28

Time Constrained Development Results ................................................................................................. 28

Delivered Therapy Considerations .......................................................................................................... 28



User Interface Considerations ................................................................................................................ 28

Manufacturability Considerations .......................................................................................................... 28

Cleaning and Sterilization Considerations .............................................................................................. 28

Design for Manufacturing Considerations .............................................................................................. 28



Table of Figures Figure 1 Wound with Access Section View ................................................................................................... 5

Figure 2 Tissue Stabilizing Augers Deployed ................................................................................................. 6

Figure 3 Needle Extended Through the Wound ........................................................................................... 7

Figure 4 Needle Tip Exchange Grasper Extended ......................................................................................... 7

Figure 5 Needle Tip Exchange Grasper Extended Section View ................................................................... 8

Figure 6 Needle Tip Exchange Grasper Contracted Section View ................................................................ 8

Figure 7 Needle Tip Exchange Grasper Retracts Curved Needle Tip Section View ...................................... 9

Figure 8 Suture System Retracting out of Access Port................................................................................ 10

Figure 9 Curved Needle Handle Safety Interlock Position Section View .................................................... 11

Figure 10 Curved Needle Handle Safety Interlock Position Detailed Section View .................................... 11

Figure 11 Curved Needle Handle Safety Pin Depressed Section View........................................................ 12

Figure 12 Bicycle Style Cable with Pull Anchors .......................................................................................... 12

Figure 13 Curved Needle Handle Trigger to Intermediate Pulley Cable Path ............................................. 13

Figure 14 Curved Needle Intermediate Pulley to Actuation Pin Cable Path ............................................... 14

Figure 15 Bicycle Style Cable with Three Pull Anchors ............................................................................... 14

Figure 16 Curved Tube Needle Actuation Pin ............................................................................................. 15

Figure 17 Complete Laparoscopic Suturing System .................................................................................... 16

Figure 18 Needle Grasper Spring Default State .......................................................................................... 17

Figure 19 Needle Grasper Collet in Closed State Section View .................................................................. 17

Figure 20 Needle Grasper Spring Depressed State ..................................................................................... 18

Figure 21 Needle Grasper Collet in Open State Section View .................................................................... 18

Figure 22 Tissue Auger Detail View ............................................................................................................. 19

Figure 23 Deploying Tissue Augers ............................................................................................................. 19

Figure 24 Auger Control Knob Detailed View ............................................................................................. 20

Figure 25 Auger Control Knob Bottomed Out ............................................................................................ 20

Figure 26 Curved Needle Hypodermic Tube ............................................................................................... 21

Figure 27 Laparoscopic Suture System Main Body ..................................................................................... 22

Figure 28 Needle Tube Torque Spindle ....................................................................................................... 22

Figure 29 Curved Needle to Torque Spindle Welded Assembly ................................................................. 23

Figure 30 Laser Star i960 Welding Station .................................................................................................. 23

Figure 31 Curved Needle Tip ....................................................................................................................... 24

Figure 32 Grasping Needle Tip Collet Step 1 Section View ......................................................................... 24

Figure 33 Grasping Needle Tip Collet Step 2............................................................................................... 25

Figure 34 Grasping Needle Tip Collet Step 3............................................................................................... 25

Figure 35 Needle Grasping Collet is Laser Welded to a Control Tube ........................................................ 26

Figure 36 Tissue Auger ................................................................................................................................ 27

Figure 37 Auger Forming Mandrel .............................................................................................................. 27



Scope The purpose of this document is to provide a technical design overview of a laparoscopic suturing

system. The document is made in response to a technical problem presented by a client to develop a

prototype suturing system.

Problem to Solve Design a system that can send a single suture across an open wound with limited access as shown in

Figure 1.

Specifications and Assumptions Wound size: 8mm x 3mm

Access size: 1”ID x 4” length, like a laparoscopic access point

Visual guidance is provided with a separate system, so assume good visibility of the wound is

available

There are organs below the wound, so the suturing solution must not puncture too deep below

the bottom of the wound

The solution will not include electronics, pneumatics or nittinol alloys

Figure 1 Wound with Access Section View



Suturing Method In this section of the document the suturing method is reviewed by focusing on the therapy that is

delivered to the wound site. The approach to the suturing system resembles how a surgeon would

suture a wound using a curved needle.

1. Deploy Tissue Stabilizing Augers Augers are deployed around the wound in order to stabilize the tissue before a curved needle

can be used as shown in Figure 2

Note the position of the pink tip of the stowed curved tube needle

Figure 2 Tissue Stabilizing Augers Deployed

2. Close the Wound with a Curved Suture Needle A curved needle is driven into the tissue as shown Figure 3



Figure 3 Needle Extended Through the Wound

3. Needle Tip Exchange Grasper The needle tip exchange grasper is extended over the tip of the needle as shown in Figure 4 and

Figure 5

Note: the actual suture is not modeled in the images shown below

Figure 4 Needle Tip Exchange Grasper Extended



Figure 5 Needle Tip Exchange Grasper Extended Section View

The collet of the needle tip exchange grasper is closed around the needle tip edge as shown in

Figure 6

Figure 6 Needle Tip Exchange Grasper Contracted Section View



4. Needle Tip Grasper Retracts Curved Needle Tip The needle tip is pulled away from the curved tube with the collet as shown Figure 7.

Note the curved tube needle body is left in place to allow for easier suture routing around the

wound site.

Figure 7 Needle Tip Exchange Grasper Retracts Curved Needle Tip Section View

5. Curved Tube is Retracted Once the suture is retrieved to the top of the access port, the curved tube body is retracted into

nominal position.

The tissue stabilizing augers are retracted.

The suture system can now be retracted out of the access port as shown Figure 8.



Figure 8 Suture System Retracting out of Access Port



Curved Tube Needle Handle Controls Overview The curved needle handle controls were inspired by Medtronics LigaSure System,

http://www.medtronic.com/covidien/products/vessel-sealing/ligasure-5-mm-blunt-tip-37-cm. The

curved tube needle handle is intended to be operated by the left hand.

1. Trigger Interlock To minimize accidental deployment of the curved needle a trigger safety interlock is used as

shown in Figure 9 and Figure 10.

Figure 9 Curved Needle Handle Safety Interlock Position Section View

Figure 10 Curved Needle Handle Safety Interlock Position Detailed Section View

http://www.medtronic.com/covidien/products/vessel-sealing/ligasure-5-mm-blunt-tip-37-cm



In order to actuate the trigger, a push button must be depressed in order to disable the safety

pin as shown Figure 11.

Note the safety pin is sprung such that when the trigger is retracted to normal position the

safety pin automatically deploys.

Note the disarm push button is also sprung so that the user has to actively hold down the safety

over-ride button with their thumb in order to actuate the curved tube needle.

Figure 11 Curved Needle Handle Safety Pin Depressed Section View

2. Stainless Cable with Bicycle Style Pull Anchors All curved tube needle actuations are performed using a set of multi-strand stainless steel cables

with bicycle style anchors as shown in Figure 12.

Figure 12 Bicycle Style Cable with Pull Anchors



The trigger pulley rotates the intermediate pulley by a cable (highlighted blue cable path shown

in Figure 13).

A secondary cable (also highlighted in blue Figure 14) is used to move the curved needle

actuation pin as shown in Figure 16.

Figure 13 Curved Needle Handle Trigger to Intermediate Pulley Cable Path

The curved needle is actuated by a second cable that has three pull anchors attached to it as

shown in Figure 14 and Figure 15.



Figure 14 Curved Needle Intermediate Pulley to Actuation Pin Cable Path

Note that the pull cable shown in Figure 15 has a hole in the center of the middle anchor. The

hole in the center of the anchor is used to actuate the curved needle pin shown in Figure 16.

Figure 15 Bicycle Style Cable with Three Pull Anchors



The green pulleys shown in Figure 16 are used to reduce the friction in the mechanism as the

cables go around sharp corners.

Figure 16 Curved Tube Needle Actuation Pin



Needle Tip Exchange Grasper Controls Overview The user controls for the needle grasper are very similar to a tri-finger ring syringe controls, like Qosina

part number: C1068, http://www.qosina.com/control-syringe-with-solid-ring-plunger-and-grip-with-

male-luer-lock-c1068

The user is intended to operate the needle tip exchange grasper with their right hand while

simultaneously holding the needle handle with their left hand as shown in Figure 17.

Figure 17 Complete Laparoscopic Suturing System

http://www.qosina.com/control-syringe-with-solid-ring-plunger-and-grip-with-male-luer-lock-c1068

http://www.qosina.com/control-syringe-with-solid-ring-plunger-and-grip-with-male-luer-lock-c1068



1. Needle Grasper Default State A spring shown in Figure 18 is used to maintain the grasper collet in a default closed state as

shown in Figure 19

Figure 18 Needle Grasper Spring Default State

Figure 19 Needle Grasper Collet in Closed State Section View



2. Needle Grasper Open State By depressing the spring on the needle grasper handle as shown in Figure 20, relative movement

of the tubes allows the grasper collet to open as shown in Figure 21.

Note the grasping collet is manufactured such that its default state is open and only by pulling it

into a tube it becomes closed. Manufacturability of the grasping collet is reviewed in

subsequent sections of this document.

Figure 20 Needle Grasper Spring Depressed State

Figure 21 Needle Grasper Collet in Open State Section View



Auger Tissue Stabilizer Controls Overview Control method for augers is inspired by various endoscopic procedures.

Figure 22 Tissue Auger Detail View

1. Deploying Tissue Augers Tissue augers are deployed by rotating clockwise the auger control knobs with your right hand

as shown in Figure 23 and Figure 24.

Figure 23 Deploying Tissue Augers



Figure 24 Auger Control Knob Detailed View

Tissue augers are fully deployed once the tissue control knobs bottom out as shown in Figure

25.

Figure 25 Auger Control Knob Bottomed Out

2. Removing Augers Auger removal is done by rotating the auger control knobs counterclockwise.

Once the augers are fully unwound from the tissue they are safe to pull out of the handle.



Manufacturability Overview The laparoscopic suturing system is currently modeled as an easily machinable prototype. The system is

modeled as a CNC machined unit because the first step in validating the concepts shown in this

document is to construct a functioning prototype. In this section of the document the manufacturability

of only the non-trivial components will be reviewed.

Curved Needle Hypodermic Tube The curved hypodermic needle tube shown in Figure 26, is made from 14 Gauge thin wall stainless steel

tube stock. In order to create this round shape without crushing the walls of the tube a round mandrel

must be installed inside of the tube prior to bending. Popular mandrel choices are as follows:

Nittinol wire

Stainless steel wire with a Teflon sleeve

Music wire

Figure 26 Curved Needle Hypodermic Tube

Once the mandrel is installed inside of the tube, the tube may be bent around a piece of round bar with

the required diameter to form this shape. Once the shape is formed, the mandrel is removed.



Laparoscopic Suture System Main Body This profile is created using a custom aluminum extrusion. The mounting holes are added in a post

process CNC milling operation. This component can also be modified so that only a CNC milling

operation is required, but it will require a few more components.

Figure 27 Laparoscopic Suture System Main Body

Needle Tube Torque Spindle The needle tube torque spindle shown in Figure 28 is created from stainless steel round stock using a

CNC lathe to create a round shape that looks like a spin top. The spin top shape is then installed into a

CNC mill and the final profile outline is made.

Figure 28 Needle Tube Torque Spindle



Curved Needle Tube and Torque Spindle Welded Assembly

Figure 29 Curved Needle to Torque Spindle Welded Assembly

The curved needle tube and torque spindle are welded together at the location illustrated in Figure 29

using a laser welder. Laser Star i960 portable laser weld station shown in Figure 30 would perform well

in this type of application.

Figure 30 Laser Star i960 Welding Station



Curved Needle Tip and Suture Assembly The curved needle tip is created using a CNC lathe as shown Figure 31. A suture is inserted and crimped

into place using a compression collet tool.

Figure 31 Curved Needle Tip

Grasping Needle Tip Collet The grasping needle tip collet is manufactured from 17-4 PH Stainless Steel. 17-4 PH stainless steel is a

good material for this application because it is corrosion resistant, has a high yield stress(good for

flexures), and because it can be heat treated after it is machined and formed into to a desired shape.

This is a common method of creating a geometry that is not easily manufactured using conventional

machining methods.

Collet is first machined using a CNC lathe as shown in Figure 32

Figure 32 Grasping Needle Tip Collet Step 1 Section View



Collet is then laser cut to obtain thin slits as shown in Figure 33.

Figure 33 Grasping Needle Tip Collet Step 2

The collet is then formed and heat treated at 1150degF for a few hours and quenched in still air

to take on the final shape and hardness as shown in Figure 34.

Figure 34 Grasping Needle Tip Collet Step 3

The grasping needle collet is welded to the tube using a laser welder as shown in Figure 35.



Figure 35 Needle Grasping Collet is Laser Welded to a Control Tube



Tissue Stabilizing Auger Tissue augers as shown in Figure 36 are created by bending wire around a round mandrel as shown in

Figure 37.

Figure 36 Tissue Auger

Figure 37 Auger Forming Mandrel



Final Discussions

Time Constrained Development Results The solution presented in this document provides a very complete solution with detailed

implementation notes of each the systems used. Keeping in mind that this solution took less than 24hrs

to develop and document, this is not an unreasonable first step towards a final product.

Delivered Therapy Considerations In the current implementation thin wire (0.5mm diameter) augers are used to stabilize tissue before a

curved needle is driven through the wound. The cost/benefit consideration here is that the augers are

not introducing a significant wound to the area, but they are minimizing tissue movement which greatly

improves accuracy of needle deployment. There are many endoscopic procedures that use similar size

augers to perform wound closing operations, like OverStich product by Apollo Endosurgery:

http://apolloendo.com/overstitch/.

User Interface Considerations The document presents preliminary user interface control considerations and assumptions. The primary

curved needle operating handle is intended to be held by the left hand and auxiliary operations that

demand slightly higher hand dexterity are operated by the right hand. Bench top testing of early

prototypes would be valuable proving ground to validate the assumption of this arrangement.

Manufacturability Considerations Manufacturing solutions to non-trivial components of this assembly are also presented in this

document. The complexity of all of the non-trivial components in this assembly is fairly low. Assuming a

laser welder, a CNC lathe and a CNC mill are available for prototyping, a well-trained hands-on engineer

can program and fabricate all of the parts needed to construct the first prototype within 7-10 working

days.

Cleaning and Sterilization Considerations Currently all of the components in the prototype are intended to be built from stainless steel or

aluminum. Material selection of the production components will vary depending on how the product is

intended to be marketed to the users, as either a single use or a many use sterilizable tool.

Design for Manufacturing Considerations Once the first prototypes are built and their functionality is verified, more time could be afforded

designing more ergonomic user interface handles. Many parts can also be made from injection molded

plastic. More time could also be spent removing visible screws from the assembly; this can easily be

accomplished with thin plastic snap in place exterior panels.

http://apolloendo.com/overstitch/

Laparoscopic Semi-Automatic Suturing System Overview Oct 16 2016 by Alex Tegzes

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