1. Opportunities and challenges in Laryngeal MicrosurgeryA user- based design of a wound closure device with potential to disruptDr Chui Chee Kong, NUS Dr David Lau Pang Cheng, SGHStefan Choo A graduate seminar presented for the degree of M.Eng

2. Quotes 3. Presentation Outline Introduction, Vocal fold pathology and intervention Study of surgical environment and tools forlaryngeal microsurgery Introduction to various types of vocal fold interventions UCD and Task analysis of based approach and analysis to design of microclips Disruptive approach to scientific research. Experimental Task Analysis- Microclip strength vs Conventional sutures. What this implies for disruptive innovation. 4. 1. Introduction, Vocal Fold Pathology and Intervention Vocal Folds in Work Contributors for vocal fold disordersLifestyleGenetics AgeLeisureStressFoodDairy Histamines Spicy Smoking Occupation products Foods 5. 1.Introduction- Vocal Cord Lesions Mostlesions form on the superficial lamina propria (Reinkes space). This results in mechanical hoarseness of voice and diminished voice Singers Nodules quality. These lesions include Does not vocal cord nodules, require surgical cysts and polyps. excision.A large vocal fold polypSurgical excision is recommended! 6. Simulated Surgical Setup2. Setup for Microlaryngeal surgery- Surgery on pigs Surgical Laryngoscope MicroscopeFramework to hold LayrngoscopeHorizontal Vertice 30 mm Vertical Vertice 18 mm Average Tool diameter : 2mm 7. 2. Setup for laryngeal microsurgery- Actual PatientTools used for Layngeal MicrosurgeryPicture obtained from (http://www.muschealth.com/bin/l/a/operation.jpg) 8. 2. Excision of a vocal fold lesionMicroflap techniqueExcision of foreign body from vocal fold(Picture from http://www.jdrntruhs.org/articles/2012/1/1/images/ JNTRUnivHealthSci_2012_1_1_7_94168_f7.jpg)Elevation of mucosal flap with L-alligator forceps 9. 2. Existing methods of Surgical Intervention and evaluation Surgical GlueSurgical GlueEasy to apply, Collagen bundles observedPicture obtained from http://www.bjorl.org/conteudo/acervo/i mages/v78n1a08-fig04.jpgSuturesPrimary HealingSuturesPrimary HealingBest healing results, diffcult to applyVocal fold scarringPicture obtained from http://www.internationalarchivesent. org/conteudo/imagesFORL/11-03-12fig05-ing.gifPicture obtained from http://www.jdrntruhs.org/viewimage.asp?img=JNTR UnivHealthSci_2012_1_1_7_94168_f8.jpg 10. 4 Pillars of Research Material Research, Design and OptimizationResearch Objectives 1. User- Centric Approach: Bridging the gap between research and the users.Design of microclipClinical Usability & ApplicationFacilitation of wound healing2.Characterizing a microclip that matches the intended period of implantation.2.1 Animal Implantation 2.2 Experimental Task Analysis- Tensile Test on Clips 2.3 Degradation Experiments 11. Lessons from User Psychology PerspectiveBJ Foggs Model Of Users Behavior Tacit11 All 3 Factors have to Come together Simultaneously for the Surgeons to make a switch 12. Dichotomy between Designer and Users Mental Model 13. StoryboardingStory-boarding: Use of illustrations to communicate ideas- Dr Lau 14. Story-boarding: Extension of initial conception of microclipsMicroclips that secure scaffold onto rhinolaryngeal wound sites via minimal access surgeriesMicroclips that secure scaffold construct onto cylindrical vessel 15. Design Considerations of MicroclipC.f. Method and material for minimal access wound closure using resorbable microclip and applicator (Patent Application)Size & Geometry High strength to weight ratio. Ease of customizabili ty to small wounds across different tissues. Mechanical stability and integrity over 2 wks.Degradability Biocompati ble with minimum cytotoxicity. Complete degradation within 2 weeks. No adverse effects from clip migration.Material ConsiderationStability of InsertionModular natureBiocompati bility Good mechanical strength Ease of processing and modification sEasy and stable deployment. No adverse mechanical effects such as tearing and injury on adjacent tissuesStandards R&D can focus on on improving properties Complemen tary features without changing bulk properties Platformisati on 16. Proposed embodiment of microclipsdeRange of thicknesses: 2.5mm- 3.5mmUS Provisional Patent Application No. 61/495,035 filed 9th June 2011, 17. Microclip under Scanning Electron MicroscopeClip before bendingClip before bendingClosed clip 18. Insertion of Microclips- Pictures and Videos 19. Analysis for animal experiments. Task AnalysisSubject: Dr David Lau, Dr Neville (Junior ENT consultant). Key variables recorded: ~12- 20 seconds, fast for insertion process of suture. ~ 35 - 45 mins, tedious and slow for insertion of clips. 20. Post sacrifice observations 21. Histology results from initial microclip studyUnpolished Magnesium clipsNon excessive granulomaPCL Coated Clips 22. Results of In- Vivo Experiments of Magnesium clip on pigs at 2 weeks implantation. Surgeons ExperienceObservation on Pigs Post ImplantationTissue ReactionImplant time. Clip: 40secs. Requires 1 helper to position clip on applicator. Suture: 12m40s/ 15s. Very tedious and strenuous process Suture may not be secured on pig #2Pig # 1: No anomalies/ distress observedPig #1: Minimal Host tissue inflammation (Only 1 clip remained at time of excision)Manipulation C-Clips weighing 0.8mg More stable insertion C-Clips weighing 0.65mg (thinner)Harder to insert, Preferred By Dr LauDr Lau would prefer a thinner embodiment of Mg clip, closer to that of a SuturePig #2: Lower pitch of pigs grunts detected. Absence of signs of distress.Pig #3: 2 clips were found after disccection.Pig #2: Dispersed granulation tissue observed throughout vocal fold. Signs of infection present. (All Clips remained at time of excision) 23. Post Implantation ResultsExtracted from , A bioabsorbable microclip for laryngeal microsurgery: Design and evaluation, J. Acta Biomaterialia, C.B. Chng, D.P. Lau, J.Q. Choo, C.K. Chui (2012) 24. Invention Vs InnovationInvention Vs Innovation Invention:A creation of a product/ knowhow for the first-time, usually as a result of scientific discovery or R&D Innovation: A product or process that makes a significant improvement in service or features to a product or existing market. 25. Disruptive InnovationsNew Dimension of Product Performance Progress Due to Innovation Sustaining , e.g. Innovations Customiza bilityLow End DisruptionNew Market Creation EffortTime 26. Disruption as a strategy PerformanceHealing Sutures Increasing Ease of UseReducecomplexities GlueFirst growth wave: Reduction in Surgical Effort- Time ComplexitiesSecond growth wave: Customization in treatment procedures, geometry, duration of wound healing Effort- Time 27. Disruptive InnovationsOvercoming RegulationsComplexity of Diagnosis & TreatmentUnpredict able & IterativeTime 28. Technology adoption CurveWound Closure Devices Glue Sutures Local Doctors in Singapore willing to experimentLocalRegional Hospitals, ok with CE Mark StandardsHigh standing hospitals, Academic Hospitals, Private Hospitals , FDA Approved StandardsLess trained surgeons 29. Experimental Task AnalysisMicroclips Vs Sutures 30. Materials and Methods Materials & MethodsMagnesium Ribbon (Sigma Aldrich, 13103)- (3,m x 0.5mm)- Width x thickness.Specifications. Molar Mass, M Density, Composition: Insol in HCL:24.31g/mol 1.738 g/cm3 min 99.5% Mg max 0.05%, of which max 0.005% Cu max 0.02% Fe max 0.01% Pb Obtained from Material Safety Data Sheet, Mg- 13103, Sigma Aldrich A blood lead level of 10 g/dL or above is a cause for concern - The US CDC, WHO Microclips were polished with 2000grit silicon carbide paper. Magnesium struts were then cut to 0.25mm thickness by Chng Boon and bent with a pair of surgical forceps. 31. Materials and Methods Materials -& Methods Mounting of Clips--Clips were manually pieced into the silicone rubber sheets with surgical cusps forceps.Singular Clips-Nylon threads with a simple knot was tied to the opposite curved ends of the clip. The free ends of the threads were then looped around 32. Materials and Methods -Materials & Methods Mounting of Clips--Clips were manually pieced into the silicone rubber sheets with surgical cusps forceps.Singular Clips-Nylon threads with a simple knot was tied to the opposite curved ends of the clip. The free ends of the threads were then looped around the silicone sheets. These sheets were clamped onto the respective ends of the tensile tester and 33. Materials and Methods Tensile -Test Procedures Tensile tester was set in place at a strain rate of 1mm/sec. Readings were taken until load drops of 40% of its maximum value. Readings with slippage was subsequently discarded. 34. 2500Plot of Single Clip Securing Thin Silicone SheetsLoad (mN)20001500Series1 1000Poly. (Series1)5000 00.511.522.5Extension (mm)33.544.5Observations: 1. Segment A- 0 to 1.5mm displacement- Logarithmic increase in Load Extension, possibly due to combined bending and elongation (Unrolling). 2. Segment B- 1.5mm to 2.5mm- Alignment 3. Segment C- 2.5 mm-3.8mm- Simple Elongation 4. Segment D- 3.8mm- 4mm- Slip 35. Analysis of Pull off Force VS Extension for Clips embedded in thick silicone rubber (1.5mm) 4000 3500Load (mN)3000 25002000 1500 1000 500 0 00.511.5 Extension (mm)22.53Observations: Clips on Thick Silicone Sheet 1. Segment A- 0 to 1.5mm displacement- Logarithmic increase in Load Extension, possibly due to combined bending and elongation (Unrolling). 2. Segment B- 1.5mm to 2.5mm- Alignment 3. Segment C- 2.5 mm-3.8mm- Simple Elongation 4. Segment D- 3.8mm- 4mm- Slip3.5 36. Plot of Single Clip Securing Silicone Sheets of different thicknesses 4000 3500Load (mN)3000 2500 2000 Clips (Thin) (n=5) 1500Clips (Thick) (n=3)1000 500 0 00.511.522.533.544.5Extension (mm) 1. Observations: Holding strength of clips is largely determined by thickness of silicone sheet. A 3.8 times increase in sheet thickness larger sustained pull off force off approximately 3N, twice that of the thinner sheets. 2. Thicker silicone sheet Reduced clip displacement before slip. 37. 3500Plot of Single Clip Vs Triple Clips in Securing Silicone Sheets3000Load (mN)2500~50 0m N2000Single Clips1500Triple Clips10005000 012345*Triple Clips (n=3) Extension (mm) Observations: 1. Triple clips reduces variance In load displacement.62. Triple clips provide a 500mN increase (28%) of maximum holding strength, accompanied by a 24% increase in maximum extension before clip detachment. 38. Plot of Load- Extension Graph: Free-Tensile Test of Fully Closed Clips with Strings Attached 3500.00Combined bending and elongation3000.00Load (mN)2500.002000.00Primary elongation1500.001000.00500.000.00 012345Extension mm6789 39. Plot of force- extension of a suture tied across Thin Silicone Sheet (mN)60005000Load (mN)40003000200010000 024 6 Force (mN) (Sample size, n=4)810 12 14 Poly. (Force (mN) (Sample size, n=4)) Extension (mm)16Observations: Suture strength >>> Strength of silicone sheet. Silicone sheet tore apart at 14.75mm. Large strains deformation of silicone sheet was similar to that of an indentation test. Silicone sheet might not be a good way to test the holding force of suture at large strain.18 40. Comparison of Load- Extension Characteristics of Clip Vs Suture at Low Extensions across two thin silicone sheets (8mm) 2500Load (mN)2000150010005000 00.511.52Extension (mm)2.53 Clip (n=5)3.544.5 41. Observations from Experimental Task AnalysisMicroclips Vs Sutures A single clip provides superior holding strength to resist low levels of strain as compared to a suture. is suitable to hold the edges of the vocal fold in place, since lateral extensions of the vocal fold edge