Introduction (Goals, literature review) - School of …research.vuse.vanderbilt.edu/srdesign/2000/group9_00/SSDS... · Web viewThis experiment showed that 2 lb. of force was adequate

Surgical Suture Delivery System

Biomedical Design 273

By:

Sarah Hembree

Ryan Ruehl

Matt Larson

Project Advisor:

Dr. Raul J. Guzman

April 24, 2001

Abstract

Our project goal is to design a device that delivers different types of sutures from

their packages to the sterile environment of the operating table for use during surgery.

We focused our design to address four separate design problems:

Opening the non-sterile package Dispensing the sterile contents Storing the different types of packages in a loading cassette Determining a package removal system so that upkeep and maintenance is

minimized

Once the SSDS is implemented, cost will be reduced through efficient use of

correct sutures and OR time. The SSDS will sit on the border of the non-sterile

environment and the sterile environment. Therefore the Scrub Nurse or the Surgeon can

press the button and obtain the proper suture with ease.

Upkeep of the SDDS is minimal; sutures are loaded from the back of the device in

stacks and the trash is removed from the vacuum chamber.

Introduction

During a surgical procedure, the surgeon and his team must interact with the

circulating nurse in order to obtain materials from a non-sterile environment. The

circulating nurse has many jobs, one of which is to deliver the sterile contents of a suture

package when needed. Since the circulating nurse often has more than one operating

room (OR) to attend to, sometimes the surgeon must wait for the suture to be delivered.

This can lead to complications of the surgery if there is an emergency, as well as an

increase in cost to the hospital or patient through both wasted sutures and OR time. The

goal of this project was to design a device that can, based on user input, select a suture

from a cassette, open the suture package, deliver the suture sterilely to the surgeon, and

dispose of the package thus decreasing the work load for the circulating nurse.

The main design problem was to separate the ends of the foil and plastic/paper

suture package. Through brainstorming, patent searches, and the use of Ideation

Workbench (see Appendix B) , we generated six ideas to accomplish this task (listed

from least to most practical):

Electrostatic Method – An electrically charged plate would be placed above the

plastic suture flap. The plastic flap of the suture package would be attracted to the

plate. Once the flap of the suture package was stuck to the plate, it could be

pinched and separated. This method was an early idea and was extremely

impractical, if not impossible.

Cutting Method – A sharp blade would cut the first ½ inch of the package

parallel to its long axis. The sides of the package would then be clamped and

pulled apart. The motion would be similar to the opening of a ketchup package.

The chances of contaminating the suture with this method are high. Also, it is a

mechanically and electronically complex method to implement.

Crimp Method – This method exploits the differences between the plastic top of

the suture package and the paper bottom. If the first ½ inch of the suture package

is crimped between two grooved metal bars (one male and one female), the plastic

will retain the crimp to a greater extent than the paper will, thus the ends of the

package will be slightly separated. The effect is subtle and will not work on the

foil packages.

Friction Method – The suture is advanced foreword on a high friction surface. A

spring tensioned rubber wheel, rotating in the opposite direction, contacts the top

part of the suture and smears the top flap back. The top flap can then be pinched

and separated. This method was unreliable and also did not work with the foil

packages.

Thermal Method – It was discovered that the plastic top of the suture package

curls away from the bottom paper part when heated. This effect was obtained at

temperatures as low as 100 F. If a heating element were placed above the suture,

the plastic would curl toward it. The plastic could then be pinched and separated

from the paper. The method will not work on the foil suture package.

Vacuum Method – The method utilizes vacuum to separate the flaps on the end

of the suture package. The flaps can then be grabbed and separated. This method

was the easiest to implement and worked on both foil and plastic suture packages.

A vacuum system similar to the one utilized in US Patent 5,557,387 was used.

Methodology

The Sutures

The sutures are made of both plastic and aluminum, and up to 12 manufactured

types are used in a hospital, 6 maximum are used in certain type of surgery, with a

maximum of 10 used of a single manufactured type. Therefore we designed our cassette

to hold 10 of each of 6 types.

Minimums Maximums

seal 0.5 cm/0.1875"

0.7 cm/0.25 "

flap 1.6 cm/0.63" 2.5 cm/0.984"

length 12.1 cm/4.76" 15.5 cm/6.1"

width 5.7 cm/2.25" 6.3 cm/2.5"thickness 1/16" 3/16"

We obtained the typically used sutures and performed force analyses on them using a

spring scale and found that the maximum force to open any single package is 2 lbs of

force.

CalculationsThere were two critical specifications that had to be met in the designing of the

SSDS. The first one of these was the extraction force necessary for removing the suture

packet from the cassette bin. The second was the vacuum pressure necessary in order to

separate the two package halves. It was around these two constraints that the machine

was constricted.

The cassette consists of six spring-loaded bins. There are two coil springs that

press a acrylic plate into the stack of sutures when fully loaded. It is from here that the

calculations start. The spring force was determined experimentally. The first step is to

determine the spring constant. This was done by measuring the original length of the

spring (with no load) and the length of the spring with some force on it.

Original length (no load) = 2 5/8”Final length (with load) =4 1/8”Standard load = 1/2 lb.Spring constant (k) =1/3 lb./in. or 58.37 N/m

Aluminum Ethicon Plastic Ethicon Plastic Dexon Plastic Other

Seal 0.7 cm 0.5 cm 0.5 cm 0.5 cm

seal-seal length 11 cm 12 cm 10.55 cm 13.1 cm

flap length 1.7 cm 1.6 cm 1.6 cm 2.5 cm

total length 12.8 cm 13.5 cm 12.1 cm 15.5 cm

Width 5.7 cm 5.75 cm 6.3 cm 5.75 cm

The spring was not compressed beyond its linear constant. This was measured

experimentally. The acrylic (Plexiglas) plate has two identical coil springs, positioned on

opposite ends. This means that for a given deflection the force on the suture packet will

be doubled. In order to determine the actual force acting on the packet it is necessary to

multiply the displacement of the acrylic plate by the spring constant (k) previously

determined. With ten of the thickest sutures in the bin the springs were compressed 1.5”

(.0318 m).

F = k*x, with (k) being 1/3 lb./in. and (x) being 1.5” F = 58.37 (N/m) * .0381 mF = 2.224 N for each spring2*F is the total force, which is 4.45 N or 1 lb.

Now that the force on the suture is known it is simple to find the required force to

pull the suture from the bin. The force on the object times the coefficient of friction will

result in the force necessary to pull the object out. A static coefficient of friction was

used as static friction is always greater than that of a moving body. The calculated force

is easily supplied by the roller.

Force on the packet = 1 lb.Coefficient of Friction = .21Force necessary to remove suture = .21 lb.

The second design constraint is the vacuum necessary to pull apart the package

halves. A spring scale was used to measure exactly how much force was required to pull

apart the flaps of the suture packet. This experiment showed that 2 lb. of force was

adequate. In order to insure a large factor of safety a large wet/dry vacuum motor was

employed to generate vacuum. The maximum pressure generated by this motor is 54” of

water or 13,450 N. It could move 120 cfm’s of air (56.6 liters per second) which far

exceeded our demands under ideal conditions. To calculate the force that the motor

could generate on the packet one must first multiply the maximum pressure that can be

generated by the area of the loose flap on the suture packet.

Pressure * Area = Force(13,450 N/m2) * (9.12 * 10-4) = 12.266 N or 2.75 lb.

The available force on the flap is 2.75 lb. which is greater than the 2 lb. that it

takes to open, therefore the motor can pull apart the suture. If the whole packet is

subjected to the pressure generated by the motor,

13,450 N/m2 * .001936 m2 = 26 N or 5.8 lb.

This generates a factor of safety of 3, ensuring proper operation.

After significant testing it was decided to use a servo and foam rubber wheels that

would clamp down on the flaps to peel apart the packet like a banana. A servo turning

clamping wheels proved easier to construct than the purely vacuum method and thus it

was adopted. The servo motor used could pull over six pounds making it a safe

alternative to the vacuum idea.

Results

Circuitry and Programming

We determined that our circuitry must follow the following steps according to the

chart:

We decided the best way to build our circuit was with a microprocessor chip. We

were recommended to use a Parallax product called the BASIC Stamp. We decided to

purchase the BASIC Stamp IIE as it had 16 I/O pins instead of the 8 on the BASIC Stamp

I. The fully programmable I/O pins directly interface TTL-level devices and connects to

non-TTL devices. In our case it controls and processes input, controls timing and

switching of motors and solenoids.

The Servo Motor Circuit

The Servo motor requires three pins of the BASIC Stamp. We chose the P0 and

P1 for the two 220 resistors, the two 0.1 F capacitors, and the 10K potentiometer (we

used the VR-10K). Then the cassette servo is connected to P2 and the belt servo is

connected to P3.

The Stepper Motor Circuit

The Stepper motor requires six pins of the BASIC Stamp. We chose the P0 and

P1 for the two 220 resistors, the two 0.1 F capacitors, and the 10K potentiometer (we

used the VR-10K) since these components and pins are also used for the servo motor.

The stepper motor circuit also incorporated a ULN 2003 chip that was placed on P4, P5,

P6 and P7 (see Appendix A for the Stepper Motor code).

The Keypad Circuit

Pins P8-P12 are used for the keypad circuit. A 74C922 chip is used with a 1F

capacitor, a 0.1F and five 10K resistors.

The Vacuum Motor

In our model, we ended up just useing our power source to directly power the

vacuum motor. However, in order to use the BASIC Stamp a single pull relay is needed

with a solid state relay. We put the solid state relay, the Sharp opto isolator S101S02

from Jameco is inserted in the circuitry with a 220 resistor. It consists of two diode

pins and AC in/out for the relay that outputs the correct current to the motor.

Therefore three pins are free, P13, P14, and P15. Please refer to the circuit or the

download section of parallax.com for the data sheets we used.

Programming

We obtained a couple programs demonstrating the movement of some of our

elements, and had to adapt them for our procedure. Overall the programs had to flow in

the following manner: keypad input; cassette servo; pause; stepper motor up; vacuum

motor on as well as the belt servo; stepper motor down. Meanwhile the photodiode (or

whatever detector) should be constantly updated to detect activation; then the vacuum

motor off as well as the belt servo off.

So far we programmed the keypad correctly to input keys 1-6. The cassette servo,

however, is not perfectly programmed to give the correct pulse according to the key

pressed. We know that the following pulses are needed to position our current cassette

(once calibrated by positioning it flat with any pulse):

Key 1 = 545 pulseKey 2 = 645Key 3 = 750Key 4 = 850Key 5 = 965 Key 6 = 1065

Please see Appendix A for all of the PBASIC code.

Safety Issues

The Sterile Suture Delivery System has practically no safety issues. According to

Designsafe (see Appendix C) few cautions exist. Wear, friction/abrasion,

drawing-in/trapping, and entanglement could occur in stocking/restocking and cleaning

by the operator. Wear is very unlikely. Friction/abrasion as well as drawing-in/trapping

and entanglement could only occur if for some reason the device was on and started

moving when the back was off, which can be eliminated in production. Therefore our

device is concluded as safe.

Economics SSDS implementation would save the cost of sutures that are wasted in an

operation as some are opened in excess. We currently have no accurate data on the cost

of the sutures as it was never provided to us. Time will also be saved which means

money will be saved. For analysis purposes we estimated that sutures cost up to $30 each

and that at least two are wasted each operation, and twenty operations requiring sutures at

a hospital occur a day for a total cost of $1200 of wasted sutures.

The market for the SSDS will be universal to any hospital or clinic that uses

sutures. Each OR would only need one, and most likely only American Hospitals or any

hospital with a plethora of resources would find this device worthwhile to purchase as it

is not a necessity.

Development cost of our particular device is about $13,000 (an average of 800

hours of labor spent at $15 plus $1000 of parts). The manufacturer could market this

device for maybe $20,000. Therefore the benefit for the manufacturer would be $7,000

each.

Therefore the benefit/cost for the hospital for purchasing would be

$20,000/$432,000 = 4.6 % assuming that the device would only last a year although it

could potentially last a lifetime. Maintenance costs would be negligible.

Photograph of finished device.

Conclusions

The operation of the Surgical Suture Delivery System (SDDS) is, by necessity,

complex. The design will function on a wide variety of packets with high repeatability

and durability. The attending physician will be allowed to select from a variety of suture

types to meet the full range of needs anticipated for a specific operating setting, allowing

flexibility and efficiency while maintaining sterility.

A human interacting with a sterile wrapped keypad performs the first step. By

pressing buttons one through six, which correspond to six different types of sutures, the

surgeon is able to have the appropriate suture selected; this starts the suture delivery

process. The buttons are labeled for each different type of suture.

The selection decision is relayed into the BASIC Stamp II that will control the

various subcomponents of the SSDS from here. The first operation performed by the

encoded chip is to turn on the vacuum motor that will be used to separate the suture

package. Next the cassette containing separate bins for each type of suture is rotated by a

servo, aligning the selected suture's bin with the bottom perforated rubber belt. This

cassette is in the shape of a hexagon and has six spring-loaded containers that can rotate

about a central axis. The belt is on two rollers, one powered by a servo. The belt is

perforated to allow air to flow through it and is designed to be slightly wider then the

suture packet, assuring a firm grip. There is a similar belt right above this one that is also

powered. When actuated, the top belt touches the bottom one and together they can grip

the packet. At this point both belts start turning.

The lower belt is raised at the command of the BASIC Stamp II chip via a stepper

motor. This stepper motor, serving in the capacity of a winch, rotates its shaft thus

winding up a drive belt translating rotational displacement into lateral displacement. This

is connected to the axle of the non-powered roller and as the motor turns the axle is

raised. At the top of the axle's travel the perforated rubber belt is pressed into the suture

bin and, with the aid of suction provided by a small vacuum tube, extracts the topmost

suture.

With the bottom belt still fully raised the suture travels between the belts to the

front of the machine. At this point the large vacuum chambers at the top and bottom of

the perforated belts take effect, drawing the loose flaps of the suture package apart.

These flaps are pulled apart by the vacuum and drawn between the powered rollers and a

foam rubber wheel on the top and bottom of the top and bottom belts, respectively.

Through the action of the powered rollers and the compressive forces of the wheels, the

top and the bottom pieces of the suture packet are drawn apart, displaying the

hermetically clean suture for the surgeon. This process is similar to peeling a banana.

When the suture is removed from the SSDS, an infrared beam is broken, indicating to the

microchip to start the disposal process. The now empty and separated packet halves are

removed from the machine by the two vacuum chambers and are drawn into the waste

storage area. The last step is to turn off the roller motors and vacuum motor, a process

performed automatically by the microchip. This completes the surgical suture delivery

process. The system is now ready for selection, delivery and opening of another packet.

Overall our project was a success although we did not finish meet our goal of

automating the continuous process.

RecommendationsOverall we recommend that the project be continued with the following things in

mind:

The Cassette

There were several design possibilities for the cassette. The hexagonal shape that we

used is not necessarily the best. It was, however, the easiest to implement. The second

version of the cassette may take a form more similar to a vertical or horizontal CD

changer. If the hexagonal design is kept, however, the six corners should be cut off so

that the walls of the suture compartments form the new corners. Cutting the corners

would decrease the distance that the belt would have to travel. If the distance that the belt

has to travel can be cut down to ½ inch or less, it would become more feasible to use a

solenoid to raise it up and down instead of a stepper motor. The stepper/pulley system is

overly complicated for the simple task of raising the rear axel. If this system is retained,

however, it would be easier to use a servo motor to wind and unwind the string. Some

other design changes include:

The sutures are not very easy to load in the back. It would be easier to load them

if the Plexiglas spring plate extended beyond the cassette so that it could be

levered down. This, however, causes problems with the rotation of the cassette.

The Transport Path/Active Site

The front of the machine needs two guides, one for the upper belt and one for the

lower belt. These guides would guide the separated flaps of the suture package in

between the top of the upper belt and the foam roller and between the bottom of

the lower belt and the foam roller.

A photosensor should be added along the transport path to detect the presence or

absence of a suture. If the photosensor is placed near the front of the machine, it

should be of the ultraviolet type so that ambient light does not trigger it.

Gears need to be used to connect the driving axel of the bottom belt to the driving

axel of the top belt. The gears must be of a very specific size and we could not

obtain two. We tried to drive the top belt by inserting another gear driven shaft,

but that proved useless. We also tried to drive the top belt with a rubber pulley,

but the pulley only slipped.

The length of the upper belt was set by whatever we could get out of a broken

copy machine. It might not be necessary for it to be that long. Also, the lower

belt is spliced with electrical tape. It would be ideal to obtain a belt of proper

length since the splices block air holes and impede rotation.

The Vacuum Chamber

The PVC container that the suture package gets sucked into needs to be modified

so that the first wrapper that enters the chamber doesn’t get sucked to the top and

cut off the suction to the rest of the machine. Also, the chamber is very

inconvenient to access and empty.

The Power Supply

A more suitable power supply should be utilized. We obtained the current power

supply from a printer just to experiment with. It could be substituted with a 12V

power supply, unless solenoids are to be used to raise and lower the belt. Since

the proper solenoid would probably be 24V, it follows that a power supply that

can supply 12V and 24V would be necessary.

Ideal SSDS: Beyond Our Scope

The “Sterile” Delivery System will be applied to all sterile wrapped products such

as catheter packages and glove packages, despite size or package material.

With one touch of a button, the sterile product will be dispensed within about six

seconds, the package will be disposed of, and the system will reset with

troubleshooting sensors, etc.

The SDS will be computer controlled so that the maintenance of refilling the

cassette and removing the trash can be updated in a log.

The computer system will track quantities used and alert the user when it should

be maintained.

The vacuum motor could possibly be replaced by the in-house suction in

operating rooms.

References and Thank You’s

http://vubme.vuse.vanderbilt.edu/group9_00/

http://parallax.com

http://jameco.com

Dr. Barnett

Steve Gebhart

Billy and Mike from Digitec Copiers

Patent website

Some helpful BASIC Stamp Programming sites:

http://groups.yahoo.com/group/basicstamps/

Contact Information

Project URL: http://vubme.vuse.vanderbilt.edu/group9_00/

Raul [email protected]

Sarah Hembree628 Occidental Dr. Claremont, CA 91711

Ryan Ruehl415 Riverbend Dr.Dandridge, TN 37725(865)[email protected]

Matthew Lange Larson911 BerkshireAnn Arbor, MI 48104(734)[email protected]

mailto:[email protected]



http://jameco.com/

http://parallax.com/

http://vubme.vuse.vanderbilt.edu/group9_00/

Appendix A – PBASIC Code – Run with Stampw.exe on Parallax CD

1. This program controls the keypad only'{$STAMP BS2e}'PROGRAM: Keypad.bas'The stamp accepts input from a 16-key matrix with the help of 'a 74C922 keypad decoder chip'_________________________________________'_________________________________________

key_val var inc 'the datalines are connected to in8- in11key_av con 12 'the data availavle is connected to in12

bttnvar var byte 'used by "BUTTON"keyvalue var nib 'variable containing pushed button code

bttnvar=0 'used by "BUTTON"

'_________________________________________

'GET THE PUSHED BUTTON'__________________________________________

debug CLS 'clears screen

test:

gosub strokekey

debug DEC ? key_val 'shows decimal value of key pressed

debug BIN3 ? key_val 'shows binary value fixed in four values

PAUSE 1000

goto test

'__________________________________________

'END THE PROGRAM'__________________________________________

loop: goto loopend

'____________________________________________

' SUBROUTINE THAT WATCHED FOR KEYS TO BE PRESSED'___________________________________________

strokekey:

watch_keys: button key_av,1,255,0,bttnvar,0,no_keysreturn

no_keys: goto watch_keys

2. This program controls the rotation of the cassette servo only. It rotates it to a specific position.

'{STAMP BS2e}

PotCW CON 0 'clockwise pot inputPotCCW CON 1 'counter-clockwise pot input

Servo CON 3 'servo control pin

rcRt VAR Word 'rc reading - rightrcLf VAR Word 'rc reading - leftdiff VAR Word 'difference between readingssPos VAR Word 'servo position

'_________________________________________________

Main:

HIGH PotCW 'discharge capsHIGH PotCCWPAUSE 1RCTIME PotCW,1,rcRt 'read clockwise,measuring charge of capsRCTIME PotCCW,1,rcLf 'read counter-clockwise

rcRt = rcRt */ $0068 MAX 250 'scale RCTIME to 0-250rcLf = rcLf */ $0068 MAX 250sPos = rcRt - rcLf 'calculate position (-250 to

250)

DEBUG Home, "position: ", SDEC sPos, " "

PULSOUT Servo, 645 'move the servoPAUSE 15

goto MainEND

For our project, the servo, once calibrated by making sure the pulses position the

bottom flat, should be given the following length pulses depending on the button

pushed on the keypad:

Key 1 = 545 pulse = Bin 1Key 2 = 645 = Bin 2Key 3 = 750 = Bin 3Key 4 = 850 = Bin 4Key 5 = 965 = Bin 5Key 6 = 1065 = Bin 6

3. This program controls the stepper motor only

'{$STAMP BS2e}

'__________________________________________________

' Stepper variables'__________________________________________________

PotCW CON 0 ' clockwise pot inputPotCCW CON 1 ' counter-clockwise pot inputCoils VAR OutB ' output to stepper coils

speed VAR Word ' delay between stepsx VAR Byte ' loop countersAddr VAR Byte ' EE address of step datarcRt VAR Word ' rc reading - rightrcLf VAR Word ' rc reading - leftdiff VAR Word ' difference between readings

'___________________________________________________

Step1 DATA %1100 ' A on B on A\ off B\ offStep2 DATA %0110 ' A off B on A\ on B\ offStep3 DATA %0011 ' A off B off A\ on B\ onStep4 DATA %1001 ' A on B off A\ off B\ on

'____________________________________________________

Initialize:

DirB = %1111 ' make stepper pins outputsspeed = 5 ' set starting speed

debug "hello"'____________________________________________________

stepper:

FOR x = 1 TO 300 ' 1 rev forwardGOSUB StepFwd

NEXTPAUSE 200

FOR x = 1 TO 300 ' 1 rev backGOSUB StepRev

NEXTPAUSE 200

StepDemo:

HIGH PotCW ' discharge capsHIGH PotCCWPAUSE 1RCTIME PotCW,1,rcRt ' read clockwise,measuring charge of capsRCTIME PotCCW,1,rcLf ' read counter-clockwise

rcRt = rcRt MAX 600 ' set speed limitsrcLf = rcLf MAX 600

diff = ABS(rcRt - rcLf) ' get difference between readings

IF (diff < 25) THEN StepDemo ' allow deadband

IF (rcLf > rcRt) THEN StepCCW

StepCW:

speed = 60 - (rcRt / 10)GOSUB StepFwdGOTO StepDemo

StepCCW:

speed = 60 - (rcLf / 10)GOSUB StepRevGOTO StepDemo

'_______________________________________________________

StepFwd:

sAddr = sAddr + 3 // 4 ' point to next stepREAD (Step1 + sAddr),Coils ' output step dataPAUSE speed ' pause between stepsRETURN

StepRev:

sAddr = sAddr + 3 // 4 ' point to previous stepREAD (Step1 + sAddr),Coils ' output step dataPAUSE speedRETURN

4. This program controls the rotation of the belt servo only. It rotates continuously (only dependent on speed) since we modified our servo.

PotCW CON 0 'clockwise pot inputPotCCW CON 1 'counter-clockwise pot inputServoB CON 2 'servo control pin


'_________________________________________________

Reps VAR nib 'counter for the FOR/NEXT loopFOR Reps = 2 TO 1

gosub MainservoNEXT

Mainservo:

HIGH PotCW 'discharge capsHIGH PotCCWPAUSE 1

RCTIME PotCW,1,rcRt 'read clockwise,measuring charge of capsRCTIME PotCCW,1,rcLf 'read counter-clockwise


250)


PULSOUT ServoB, (5) 'move the servoPAUSE 15return

END

5. First attempt at putting the keypad input to the cassette servo:'{$STAMP BS2e}'PROGRAM: Keypad.bas'The stamp accepts input from a 16-key matrix with the help of 'a 74C922 keypad decoder chip'_________________________________________

' keypad variables'_________________________________________



bttnvar=0 'used by "BUTTON"'________________________________________'' servo variables'__________________________________________

PotCW CON 0 'clockwise pot inputPotCCW CON 1 'counter-clockwise pot inputServo CON 2 'servo control pin

rcRt VAR Word 'rc reading - right

rcLf VAR Word 'rc reading - leftdiff VAR Word 'difference between readingssPos VAR Word 'servo position

'_________________________________________________

'_________________________________________



test:

gosub strokekey


PAUSE 1000

IF key_val = 0 THEN cassetteoneIF key_val = 1 THEN cassettetwoIF key_val = 2 THEN cassettethreeIF key_val = 4 THEN cassettefourIF key_val = 5 THEN cassettefiveIF key_val = 6 THEN cassettesix

'__________________________________________

'END THE PROGRAM'__________________________________________

loop: goto loopend

'____________________________________________


strokekey:


no_keys: goto watch_keys'____________________________________________'' SUBROUTINES THAT OUTPUTS A PULSE TO THE CASSETTE'____________________________________________

cassetteone:



250)


PULSOUT Servo, (545) 'move the servoPAUSE 15

GOTO cassetteone

IF key_val <> 0 THEN loop'________________________________________________

cassettetwo:



250)



GOTO cassettetwoGOTO loop

'________________________________________________________

cassettethree:



250)



GOTO cassettethreeGOTO loop

'________________________________________________________

cassettefour:



250)



GOTO cassettefourGOTO loop

'________________________________________________________

cassettefive:



250)



GOTO cassettefiveGOTO loop

'________________________________________________________

cassettesix:



250)



GOTO cassettesixGOTO loop

6. Program with keypad input to the cassette servo and the belt servo'{$STAMP BS2e}'PROGRAM: Main.bas'The stamp accepts input from a 16-key matrix with the help of 'a 74C922 keypad decoder chip'_________________________________________

' keypad variables'_________________________________________



bttnvar=0 'used by "BUTTON"'________________________________________'' servo variables'__________________________________________

PotCW CON 0 'clockwise pot inputPotCCW CON 1 'counter-clockwise pot inputServo CON 3 'servo control pinServoB CON 2 'servo control pin


'_________________________________________________

'_________________________________________



test:

gosub strokekey


PAUSE 1000

IF key_val = 0 THEN cassetteoneIF key_val = 1 THEN cassettetwoIF key_val = 2 THEN cassettethreeIF key_val = 4 THEN cassettefourIF key_val = 5 THEN cassettefiveIF key_val = 6 THEN cassettesix

'__________________________________________

'END THE PROGRAM'__________________________________________

loop: goto loopend

'____________________________________________


strokekey:


no_keys: goto watch_keys'____________________________________________'' SUBROUTINES THAT OUTPUTS A PULSE TO THE CASSETTE'____________________________________________

cassetteone:

IF key_val = 0 OR key_val = 15 THEN pulseonepulseone:



250)


PULSOUT Servo, (545) 'move the servoPULSOUT Servo, (545) 'move the servoPULSOUT Servo, (545) 'move the servoPULSOUT Servo, (545) 'move the servoPULSOUT Servo, (545) 'move the servoPULSOUT Servo, (545) 'move the servoPULSOUT Servo, (545) 'move the servoPULSOUT Servo, (545) 'move the servoPULSOUT Servo, (545) 'move the servoPULSOUT Servo, (545) 'move the servoPAUSE 15

IF key_val <> 0 OR key_val <> 15 THEN beltservo

'________________________________________________

cassettetwo:



250)


PULSOUT Servo, (645) 'move the servoPULSOUT Servo, (645) 'move the servoPULSOUT Servo, (645) 'move the servoPULSOUT Servo, (645) 'move the servoPULSOUT Servo, (645) 'move the servoPULSOUT Servo, (645) 'move the servoPULSOUT Servo, (645) 'move the servoPULSOUT Servo, (645) 'move the servoPULSOUT Servo, (645) 'move the servoPULSOUT Servo, (645) 'move the servo

PAUSE 15

IF key_val = 1 OR key_val = 15 THEN cassetteoneIF key_val <> 1 OR key_val <> 15 THEN beltservo

'________________________________________________________

cassettethree:



250)


PULSOUT Servo, (750) 'move the servoPULSOUT Servo, (750) 'move the servoPULSOUT Servo, (750) 'move the servoPULSOUT Servo, (750) 'move the servoPULSOUT Servo, (750) 'move the servoPULSOUT Servo, (750) 'move the servo

PULSOUT Servo, (750) 'move the servoPULSOUT Servo, (750) 'move the servoPULSOUT Servo, (750) 'move the servoPULSOUT Servo, (750) 'move the servoPAUSE 15


'________________________________________________________

cassettefour:



250)




'________________________________________________________

cassettefive:



250)


PULSOUT Servo, (965) 'move the servoPULSOUT Servo, (965) 'move the servoPULSOUT Servo, (965) 'move the servoPULSOUT Servo, (965) 'move the servoPULSOUT Servo, (965) 'move the servoPULSOUT Servo, (965) 'move the servoPULSOUT Servo, (965) 'move the servoPULSOUT Servo, (965) 'move the servoPULSOUT Servo, (965) 'move the servoPULSOUT Servo, (965) 'move the servoPULSOUT Servo, (965) 'move the servo

PAUSE 15


'________________________________________________________

cassettesix:



250)




'________________________________________________________

beltservo:

Reps VAR nib 'counter for the FOR/NEXT loopFOR Reps = 2 TO 1

gosub MainservoNEXT

Mainservo:

HIGH PotCW 'discharge capsHIGH PotCCWPAUSE 1

RCTIME PotCW,1,rcRt 'read clockwise,measuring charge of capsRCTIME PotCCW,1,rcLf 'read counter-clockwise


250)

DEBUG Home, "position: ", SDEC sPos, " "PULSOUT ServoB, (1) 'move the servoPAUSE 20return

END

Appendix B – Innovation Workbench

Ideation Problem Solving ProcessA TRIZ-based step-by-step procedure designed to reveal Innovation

Concepts.

For More Information: Ideation Web Page

Innovation Situation Questionnaire1. Brief description of the problem

Surgical Suture Delivery System

Problem: During surgery, two nurses are required to obtain and open various sutures. This process is where one of the most common breaks in sterile technique occurs and is inconvenient.

Project Goal: To design a device that will minimize the chance for a break in sterile technique as well as increase operating room efficiency by delivering proper suture to the surgeon at the touch of a button.

2. Information about the system

2.1 System name

Surgical Suture Delivery System 2001 (SSDS 2001)

2.2 System structure

The system consists of two main parts. The first part is a cassette that contains the various types of sutures. The second part is a suture transport/opening pathway that delivers the suture without the outer package to the surgeon.

2.3 Functioning of the system

The primary useful function is the delivery of a sterile suture to the surgeon

The purpose of performing this function is to expedite the process of delivering sutures from the nonsterile environment to the sterile field of the operating table.

The current process is done manually and is error prone and inefficient.

2.4 System environment

http://www.ideationtriz.com/

The system environment is the operating room.

3. Information about the problem situation

3.1 Problem that should be resolved

The current suture opening and delivery method is inefficient and sometime results in breaks in sterile technique.

3.2 Mechanism causing the problem

The source of the problem lies in the multiple human interactions with the suture.

3.3 Undesired consequences of unresolved problem

Infection could occur and time is wasted.

3.4 History of the problem

The inefficiency of transport of unsterile sutures to the sterile environment has been a problem since introduction of sutures to the operating room. The current solution involves nurses manually transporting the suture between the environments.

3.5 Other systems in which a similar problem exists

This situation is common in the operating room and is paralleled by the problems arising from the use of catheters, gloves, etc.

3.6 Other problems to be solved

Cost, size, package separation, wrapper disposal

4. Ideal vision of solution

The ideal solution would be a compact device that can store and deliver a sterile suture in under seven seconds at the touch of a button.

5. Available resourcesSample suturesParts from suppliersAll necessary equipment to build prototypeConsulting professorsDr. Guzman

6. Allowable changes to the system

Any change is allowed as long as it fits the aforementioned parameters.

7. Criteria for selecting solution concepts

Results from Designsafe software (safe)Easy to operateMechanically feasibleMeets all of the criteria

8. Company business environment

The main working environment will be the BME lab at Vanderbilt University. We will use Vanderbilt Biomedical and Mechanical Engineering resources, Vanderbilt Medical Center resources, and outside resources.

9. Project data

Senior Design Students:Sarah Hembree [email protected] Ruehl [email protected]

Project Mentor:Dr. Raul Guzman [email protected]

Problem Formulation1. Build the Diagram

2. Directions for Innovation

3/17/01 3:40:33 PM Untitled 1

1. Find an alternative way to obtain [the] (input suture selection) that provides or enhances [the] (cassette rotation).

2. Find an alternative way to obtain [the] (cassette rotation) that offers the following: provides or enhances [the] (transfer of suture to the active site), does not require [the] (input suture selection).

3. Find an alternative way to obtain [the] (transfer of suture to the active site) that offers the following: provides or enhances [the] (opening mechanism), does not require [the] (cassette rotation).

4. Find an alternative way to obtain [the] (opening mechanism) that offers the following: provides or enhances [the] (suture enters delivery site), does not require [the] (transfer of suture to the active site).

5. Find an alternative way to obtain [the] (suture enters delivery site) that offers the following: provides or enhances [the] (wrapper removed), does not require [the] (opening mechanism).

6. Consider transitioning to the next generation of the system that will provide [the] (wrapper removed) in a more effective way and/or will be free of existing problems.

7. Find an alternative way to obtain [the] (wrapper removed) that does not require [the] (suture enters delivery site).

3/17/01 4:15:04 PM new diagram

1. Consider transitioning to the next generation of the system that will provide [the] (vacuum suction) in a more effective way and/or will be free of existing problems.

2. Find an alternative way to obtain [the] (vacuum suction) that does not require [the] (opening mechanism).

Prioritize Directions1. Directions selected for further consideration

First priority

opening mechanism

Long-term

effective cassette and circuit design

Out-of-scope

computer controlled inventory, selection

failure detection circuitry

2. List and categorize all preliminary ideas

Best Ideas:

Vacuum Method

Thermal Method

Friction Method

Backup Ideas:

Crimp Method

Cutting Method

Velcro Method

Electrostatic Method

Develop Concepts1. Combine ideas into Concepts

sub-problem: opening suture package

Ideas: vacuum and thermal methods

Compare: vacuum method can open all types of package, independent of package material, but it requires a perfect seal. The thermal method requires plastic package, but is very accurate. Therefore the vacuum method is more universal, but the thermal method might be less prone to failure.

We will apply a copy machine model for the vacuum method; the paper feeding mechanism.

2. Apply Lines of Evolution to further improve Concepts

Increasing Ideality:

Universality

---------------

Mechanical obstacles

Overcoming mechanical obstacles: intensify field, intensity vacuum

Increasing controllability; introducing negative feedback

increase vacuum in response to suction failure

reallocating vacuum in response to failing suction

Reduce complexity (simplification)

Specialization

This mechanism is specialized for sutures

Improve Reliability

Duplication of critical elements

Add more vacuum pumps/ducts

Evaluate Results1. Meet criteria for evaluating Concepts

Secondary Problem: ineffective vacuum

2. Reveal and prevent potential failures

Overcoming mechanical obstacles: intensify field, intensity vacuum

Increasing controllability; introducing negative feedback

increase vacuum in response to suction failure

reallocating vacuum in response to failing suction

Improve Reliability

Duplication of critical elements

Add more vacuum pumps/ducts

3. Plan the implementation

Measure force generated by vacuum system, compare force calculated to the slip/grip force calculations

Perform trials of the vacuum method to determine failure rates

Experiment with varying hole size in belts to determine the ideal size/number of holes

Determine the maximum force to open suture and the minimum suction in force and flow rate

Determine the speed of the belt without breaking suction

Determine how long the transport path length will be

Determine the time of belt rotation, before and after the photosensor detection

Appendix C- Designsafe Review Report

Appendix D – Additional Circuitry and Programming Materials

Documents

Introduction (Goals, literature review) - School of …research.vuse.vanderbilt.edu/srdesign/2000/group9_00/SSDS... · Web viewThis experiment showed that 2 lb. of force was adequate