Respirator Research Update: Human Interface, Materials and Manufacturing Technology Perspectives

Transcription

1 Respirator Research Update: Human Interface, Materials and Manufacturing Technology Perspectives Sundaresan Jayaraman Georgia Institute of Technology June 3, 2010

2 Overview of Presentation The Challenges: Design and Real-World The Opportunity: Next Generation Device Design and Development Framework Results Concluding Thoughts Acknowledgements

3 The Design Challenges Cost Degree Successful of Protection Comfort Regulations Ensure Performance Efficacy Ensure Successful Protection During Use Avoid Leakage [Crutchfield et al., 1999] Fundamental Occurs when Donned Transient Occurs during Use Ensure Comfort Enhance Compliance with Usage of Device Maintain or Reduce Total Cost of Ownership (TCO) TCO = Respirator Cost + Fit-Testing Cost + Disposal Cost + Logistics (Procurement, Storage, ) + IOM 2007

4 The Real-World Challenges Limitations of Current Generation of Respirators Facial Profiles Beard, Children, Need for Fit-Testing Cost, Time, Compliance, Disposable Environmental Impact Potential Shortages (e.g., H1N1 Pandemic) Manufacturers Running at Full Clip Fortunately, it was, The Flu Season that Fizzled.» The Wall Street Journal, March 2, 2010

5 The Opportunity Harness Advancements in Technologies Understanding User Needs Materials Structures Manufacturing Methods

6 Comfort Filtration Efficiency Continuum Pantyhose Comfort High The Goal Low Filtration Efficiency High Current Respirators Low Goal: The Next Generation Respirator No Fit-Test Reusable Comfort, Fit and Shape Conformance Plastic Sheet

7 The Design Toolkit Evidence-based Performance Requirements Will Determine the Choice of Materials Structures Manufacturing Tech. Will Influence the Properties and Lead to the Design of the Respirator Gather Evidence from Users

8 Materials, Structures and Manufacturing Technologies Traditional Respirators/Masks Nonwovens Charged Polypropylene Filters Mechanisms for Trapping Particulates 3M N95 Healthcare Particulate Respirator & Surgical Mask

9 Alternative Approaches: Back to the Roots Other Manufacturing Technologies Weaving / Knitting / [ Nonwovens] Yarn Properties Fiber Type Fiber Cross-Sectional Shape Linear Density Twist Level. Porosity Fabric Cover Permeability Fabric Properties Threads Densities Structure

10 Parameters Influencing Cover of Woven Fabrics Structure of Yarn in the Fabric Shape: Circular, Elliptical, Flat Packing Density of Fibers in Yarn Twisted, Filament ** Type of Material Spun Yarn Filament Yarn Flat, Textured Cover = Proportion of Surface Area Covered by Yarns in a Unit Surface Area of Fabric

11 Structural Variations

12 Design And Develop Comfortable No Fit-Test Reusable Research Objectives Textile-based Respirators For Use by Healthcare Workers During an Influenza Pandemic Next Generation Healthcare Respirator

13 What are the User s Needs? Degree of Protection Usability Manufacturability Wearability The Needs Maintainability Aesthetics Durability Cost Needs are in the Language of the Users Subjective, Easy to Express

14 Survey Instrument & Protocol User Profile Training Using the Device Post-Use (Disposal) Likes and Dislikes Changes to Device Initial Development and Refinement Discussions with Broad User Population: Focus on Quality

15 Highlights of Findings Profiles of Users Work Environment Hazards in Work Environment Typical Duration of Use Duration of Continuous Use of Single Device without Doffing Number of Devices / Day Reasons for Changing Devices during Day Device Brand Preference Device Disposal Physician, Surgeon, Anesthesiologist, Pulmonologist, Nurses including Head Nurse, Safety Officer Hospitals, Physician Practice, Research Laboratory Patients (including TB) and Animals minutes/use User writes name on device, which is then hung outside the patient s room and put on when entering the room; upon exiting, the device is removed and hung until next use. No Standard method to don/doff to prevent decontamination. Device discarded at the end of the day. Typical: 4 hours Extreme: 8 hours Changes with number of patients treated and number of allergens. The same device is not used for different patients or allergens. Movement from Patient to Patient Fear of Suffocation Dampness due to Breathing and Talking during Use Physical Dislodgement Sweating in Research Lab Environment Varies As Biohazard Waste

16 Highlights (Cont d) Factors Influencing Device Selection (in order of importance) Fit Testing Complaints / Dislikes with Device Efficacy Cost Supplier Relationship Size Range Storage Requirements A Single Brand Fitting all users is desired (logistics simpler). Mandatory for Nursing Staff on an Annual Basis Not required for Physicians Breathing is Impaired Discomfort Fear of Suffocation Hyperventilating Hot and Damp due to Condensation of Breath in Device Fogging of Glasses Scratchy Skin Breaks Down Bruises to Nose due to Fitting Tightly Marks Multiple Straps Difficult to adjust and significantly hurts hair and messes it up. Interferes with Stethoscope Communication Impaired oneed to speak at least 20% louder oelderly patients who rely on lip reading to augment hearing loss have greater difficulty comprehending words. Heavy Thick Duckbill Design contributes to shifting of device during talking and increases potential for leakage. Difficult to fit individuals with narrow cheekbones. Facial hair interferes with use

17 Highlights (Cont d) Desired Changes A Single Strap Lightweight End of Life Indicator Fit Indicator to Assure Fit Should not impair the senses of touch, hearing, taste, sight and reflex No Latex Foldable Better Aesthetics Visually Appealing Findings Help in the Next Phase: Design of System

18 Fabric-based Filtration Systems

19 The Predicate (Baseline) Device Kimberly-Clark N95 Respirator Medical Mask (PFR95) Choice of Device: Being Used as a Reference Air Permeability (ASTM D ) Measure Air Flow through Sample K-C s s PFR95 One End of the Continuum A Pantyhose The Other End of the Continuum Our Goal Find the Optimum!

20 A Framework for Design and Development Requirements Performance Requirements Functionality Usability Wearability Shape Conformability Durability Maintainability Manufacturability Affordability Materials & Translate Into Are Achieved Through Properties Fabrication By Applying These Technologies Desired Properties Barrier Properties Resistance to Transmission of Microorganisms Particulates Fluids Comfort Properties Hand Air Permeability Moisture Absorption Stretchability Bending Rigidity Weight Tensile Strength & Modulus Form-Fitting Manufacturability Cost Design Lead To Barrier Component (BC) Comfort Component (CC) Form-Fitting Component (FFC) Materials Barrier Component (BC) Polypropylene Filter Media Electrostatic Charged Filters Textile Fibers Comfort Component (CC) Polypropylene MicrodenierPolyester Blend Form-Fitting Component (FFC) Spandex Manufacturing Technologies Novel Nonwoven Mask Assembly Cutting, Sewing Straps Design Parameters Design Parameters Filter Density Filter Composition Fiber Length, Fineness, Strength, Elongation, Moisture Absorption, Density, Friction, Cross-Sectional Shape Strength, Elongation, Fineness, Creep/Elastic Recovery Design Parameters Threads Density, Structure, Yarn Counts Matt Density, Type of Bonding Design Parameters Number of Layers, Lay-up Orientation

21 Engineered Structure: Test Results Sample Number of Washes Filtration Efficiency (%) Pressure Drop (inches) Test Test Test Test Test Test Test Protocol: ASTM F Linear Velocity: 11cm/sec Flow Rate: 85 L/Min

22 Effect of Washing on Engineered Structure # Washes = 0 # Washes =3 # Washes =10 Optical Microscope 40x # Washes = 20

23 The Balancing Act Air Permeability Requires Low Cover Factor Particle Filtration -Requires High Cover Factor Optimum Level of Properties Through Combinations of Fiber, Yarn, and Fabric Structures

24 The Face Seal Achieving the Right Fit

25 Meeting the Challenge: Characteristics of the Face-Seal Interface Shape Conformance (Flexibility) Slip Resistance Shock Absorption Vibration Resistance Comfort Texture Hypo-Allergenic Easy to Put On, Stay in Place Prevent Leakage

26 Thermoplastic Elastomers Thermoplastic Elastomers(TPE) Flexible Materials that Can be Stretched Repeatedly at Room Temperature and Returned to Original Length When Released (Deformation Removed) Easy for Processing Spandex Commercially Available

27 Design for Fit + Filtration Spandex for Fit Filtration System Strap

28 Concluding Thoughts Research Initiative: Exciting and Challenging Evidence-based Performance Requirements On-going Investigations Foundation for Design

29 Acknowledgments CDC Research Funding Research Team Members Dr. Subramanian Sundaramoorthy Dr. Palaniswamy Nallampalayam KolonGlotech Industry Partner Ms. Sungmee Park Staff Researchers NPPTL Testing