Mechanical Testing System Coupled with an Environmental Chamber for HydrogelsOverviewProblem StatementBackground - HydrogelsBackground - BME 301Environmental Chamber Design Specifications/ConstraintsEnvironmental Chamber TestingSlide 8Slide 9Slide 10Background - Creep TestingComponents of Creep Testing ApparatusProduct Design SpecificationsDesign Alternatives: Digital CameraDesign Alternatives: Ultrasonic TransducersDesign Alternatives: Linear Displacement TransducerFinal DesignTestingExperimental Set-upPreliminary ResultsSlide 21Preliminary ConclusionsFuture WorkAcknowledgementsMechanical Testing Mechanical Testing System Coupled with an System Coupled with an Environmental Chamber Environmental Chamber for Hydrogelsfor HydrogelsTeam: Charlie Haggart, Gabriel J. Martínez-Díaz, Team: Charlie Haggart, Gabriel J. Martínez-Díaz, DarcéeDarcée Nelson, and Michael PichéNelson, and Michael PichéClient: Weiyuan John Kao, Ph.D.Client: Weiyuan John Kao, Ph.D.Advisor: Paul ThompsonAdvisor: Paul ThompsonBME 400 Midsemester PresentationBME 400 Midsemester Presentation10/18/0210/18/02OverviewOverviewProblem StatementProblem StatementProject BackgroundProject BackgroundDesign Specifications & ConstraintsDesign Specifications & ConstraintsEnvironmental ChamberEnvironmental Chamber•Prototype TestingPrototype TestingCreep Testing SystemCreep Testing System•Design AlternativesDesign AlternativesFuture WorkFuture WorkAcknowledgementsAcknowledgementsProblem StatementProblem StatementTest compatibility of environmental chamber Test compatibility of environmental chamber built during BME 301 with Instron 1000built during BME 301 with Instron 1000Test hydrogel samples using Instron 1000Test hydrogel samples using Instron 1000Compare results with Instron 5548 dataCompare results with Instron 5548 dataDesign and build creep testing system Design and build creep testing system Study viscoelastic properties of hydrogelsStudy viscoelastic properties of hydrogelsBackground - HydrogelsBackground - HydrogelsCross-linked polymeric structuresCross-linked polymeric structuresAbility to absorb water and/or biological Ability to absorb water and/or biological fluidsfluidsExperience physical changes Experience physical changes Dependent onDependent on pH and temperature pH and temperatureApplications:Applications:Drug delivery vessels, bandages, and skin Drug delivery vessels, bandages, and skin adhesives for wound/burn care adhesives for wound/burn careBackground - BME 301Background - BME 301Drafted procedure to fabricate tensionDrafted procedure to fabricate tension stencils (used in making hydrogel stencils (used in making hydrogel samples)samples)In accordance with ASTM standardsIn accordance with ASTM standardsDesigned and built environmental Designed and built environmental chamberchamberUsed in tensile testing of hydrogel samplesUsed in tensile testing of hydrogel samplesFor use with Instron 1000 in 1313 Eng. HallFor use with Instron 1000 in 1313 Eng. HallEnvironmental Chamber Environmental Chamber Design Design Specifications/ConstraintsSpecifications/ConstraintsWithstand temperature (25 – 40˚C) and Withstand temperature (25 – 40˚C) and pH (4 – 8) of solutionpH (4 – 8) of solutionCause no interference with tensile testing Cause no interference with tensile testing of hydrogel samplesof hydrogel samplesSolution must not contact Instron 1000 Solution must not contact Instron 1000Environmental Chamber TestingEnvironmental Chamber TestingTemperature TestTemperature Test4 L deionized H4 L deionized H22OOPhysiological 37 °CPhysiological 37 °CASTM tensile test ASTM tensile test duration - 0.5 to 5.0 duration - 0.5 to 5.0 minutes minutes Results:Results: 2.5 °C drop 2.5 °C drop over 30 minutes over 30 minutes durationduration3434.53535.53636.53737.50 5 10 15 20 25 30 35Time (s)Temperature (C)Trial 1 Trial 2Environmental Chamber TestingEnvironmental Chamber TestingGrip SensitivityGrip SensitivityInstron 2711 Series - lever action gripsInstron 2711 Series - lever action gripsWill grips be sensitive enough for tensile Will grips be sensitive enough for tensile testing of hydrogels?testing of hydrogels?•YESYES•80% of hydrogel samples fractured at gauge length80% of hydrogel samples fractured at gauge length•20% fractured at point of contact with lower grip20% fractured at point of contact with lower gripEnvironmental Chamber TestingEnvironmental Chamber TestingCompatibility with Instron 1000Compatibility with Instron 1000Issue: Top plate (obstruction) Issue: Top plate (obstruction) •Solution: Removal of plateSolution: Removal of plateIssue: Protective seal (moisture) Issue: Protective seal (moisture) •Solution: Machine new adaptorSolution: Machine new adaptorBackground - Creep TestingBackground - Creep TestingTests effects of prolonged Tests effects of prolonged loading of a materialloading of a materialMonitors strain of a Monitors strain of a material under a constant material under a constant stress for a long period of stress for a long period of time.time.AFσstressLΔLεstrainiComponents of Creep Testing Components of Creep Testing ApparatusApparatus•Specimen GripsSpecimen Grips To hold specimen during testingTo hold specimen during testing•ExtensometerExtensometer To measure the change in length of the To measure the change in length of the specimenspecimen•Loading device (Weights)Loading device (Weights)•ChamberChamber To keep specimen in conditions for which the To keep specimen in conditions for which the creep properties are of interestcreep properties are of interestProduct Design SpecificationsProduct Design SpecificationsChamberChamberMaterial: Material: transparent, durable, easy to manufacture, insulating, and transparent, durable, easy to manufacture, insulating, and resistant to corrosionresistant to corrosionMust maintain constant temperatureMust maintain constant temperatureExtensometerExtensometerAccurate to 1 mm and preciseAccurate to 1 mm and preciseCapable of logging data for up to 1 dayCapable of logging data for up to 1 dayGripsGripsMust allow for fracture at gauge lengthMust allow for fracture at gauge lengthMust not slipMust not slipLoading System (Weights)Loading System (Weights)Must be variable between 0 and 50 g.Must be variable between 0 and 50 g.Design