Probing Pain Perception

Client: Christopher Coe, Ph.D.Department of Psychology

Advisor: Professor Willis Tompkins

Team Members:Stacey Hoebel, Jeff Swift, Anna

Karas

University of Wisconsin - Madison Biomedical Engineering Design Courses

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FIBROMYALGIAFIBROMYALGIAChronic musculoskeletal pain and fatigue Chronic musculoskeletal pain and fatigue disorder disorder Cause of the disease is still unknown Cause of the disease is still unknown Associated sleep disorder called the alpha-EEG Associated sleep disorder called the alpha-EEG anomalyanomalyTreatmentsTreatments

THERMO GRILL ILLUSION OF PAINTHERMO GRILL ILLUSION OF PAINPain is a homeostatic emotionPain is a homeostatic emotionNeurons and Central Nervous SystemNeurons and Central Nervous System

Previous DesignPrevious DesignCreated by A.D. Craig (Univ. of Arizona)Created by A.D. Craig (Univ. of Arizona)

Alternating warm (40 C) and cool rods (20 C)Alternating warm (40 C) and cool rods (20 C)

About 8” x 8” with 0.5” About 8” x 8” with 0.5” diameter thermal rodsdiameter thermal rods

Presumed to be electricPresumed to be electric

Ominous LookingOminous Looking

Problem StatementProblem Statement

Design a device to test pain sensitivity in Design a device to test pain sensitivity in patients with generalized pain disorders. patients with generalized pain disorders.

The alternating warm and cool The alternating warm and cool components of the device activate sensory components of the device activate sensory receptors and neurological thermal receptors and neurological thermal pathways to create the illusion of pain.pathways to create the illusion of pain.

Design ConstraintsDesign Constraints

Consistent temperature componentsConsistent temperature components– Warm: 40Warm: 40°C°C Cool: 20°CCool: 20°CReach temperatures in 1 sec.Reach temperatures in 1 sec.SafeSafeReusableReusableOn/off power temperature controlOn/off power temperature controlNon threatening appearanceNon threatening appearanceEasy to operateEasy to operate

Design 1: Peltier DeviceDesign 1: Peltier Device

Peltier devicePeltier device– Peltier effectPeltier effect– Internal MechanismInternal Mechanism

Temperature controlTemperature control– Surface 1Surface 1– Surface 2Surface 2

Parallel arrangment of Parallel arrangment of Peltier devicesPeltier devices

Design 1: Peltier DeviceDesign 1: Peltier Device

AdvantagesAdvantages– Friendly user-interfaceFriendly user-interface– Electrical components Electrical components

minimize spaceminimize space– ReplicableReplicable

DisadvantagesDisadvantages– Time constraintTime constraint– Custom made Peltier Custom made Peltier

devicesdevices

Design 2: Water and Copper Design 2: Water and Copper TubingTubing

Design 2: Water and Copper rodsDesign 2: Water and Copper rods

AdvantagesAdvantages– Constant water temperatureConstant water temperature– Copper tubing conductionCopper tubing conduction– ConstructionConstruction

DisadvantagesDisadvantages– Device SetupDevice Setup– AestheticsAesthetics

Design 3: Electronic Heater and Design 3: Electronic Heater and Copper Rods Copper Rods

Warm componentWarm component– Electric resistance heatersElectric resistance heaters– Portable on/off switchPortable on/off switch– Temperature controllerTemperature controller

Asymptotic heating Asymptotic heating

Cool componentCool component– Solid copper rodsSolid copper rods

Thermal ConductivityThermal ConductivityMaintain relatively constant temperatureMaintain relatively constant temperature

Design 3: Electronic Heater and Design 3: Electronic Heater and Copper RodsCopper Rods

AdvantagesAdvantages– Temperature and time constraints satisfiedTemperature and time constraints satisfied– Safe due to asymptotic temperature Safe due to asymptotic temperature

controlcontrol– Simple user interfaceSimple user interface

DisadvantagesDisadvantages– Material selectionMaterial selection– CostCost

Decision MatrixDecision MatrixDesignDesign Water & Water &

tubingtubingPeltierPeltier Heaters & Heaters &

tubingtubingTime to reach Time to reach temp.temp.

88 11 99

Temp. ControlTemp. Control 55 99 1010CostCost 99 55 77Ease of Ease of ManufacturingManufacturing

88 66 55

User interfaceUser interface 00 1010 1010TotalTotal 3030 3131 4141Rating: 0=worst, 10=best

Chosen Design: Electronic Heater Chosen Design: Electronic Heater and Copper Rodsand Copper Rods

User friendlyUser friendly– Simple electric switchSimple electric switch

Aesthetically pleasingAesthetically pleasingCompactCompactLow maintenanceLow maintenanceReplicable experimentsReplicable experimentsMeets specifications for temperature and Meets specifications for temperature and timetime

Future WorkFuture Work

Heat transfer calculationsHeat transfer calculations– Power, size necessary for electric heating Power, size necessary for electric heating

componentscomponents– Thickness of cool copper rods to maintain Thickness of cool copper rods to maintain

constant temperatureconstant temperature

Research on temperature controllersResearch on temperature controllersExperiments to determine optimal Experiments to determine optimal configurationconfiguration

Questions??Questions??