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This presentation was given in 2010 at a British Society of Rheology meeting on Biorheology held at Nottingham University. The presentation describes the rheology of certain dysphagia formulations and then introduces "The Cambridge Throat". A mechanical device for following the way fluids are drawn into the throat by a model tongue and then how the fluid flows down the back of the throat.
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The Rheology and Processing of fluids used to assist symptoms of Dysphasia
ByMalcolm Mackley,
Christine Rowan, Rosemary Anthony Edward Thien, Ivy Liu
Department of Chemical Engineering and BiotechnologyUniversity of Cambridge
UK
Background - Dysphagia
Mouth
Tongue
Epiglottis
Airway
Oesophagus
Background - Dysphagia
Video courtesy of Speech and Language Therapy department, Addenbrooke’s Hospital
Thickener solutions
Microscope images taken at 50x magnification of the two commercial thickeners in water with a solid fraction of 4.8%.
Nutilis
100 μm
Thicken Up
100 μm
Starch plus polymer? Starch only?
Rheological CharacterizationSteady shear; apparent viscosity
concentration 2.5g/50 ml water
Nutilis, Starch plus polymer?
Thicken Up, starch only?
Both Power Law Fluids
Oscillatory Strain Sweep Data for Nutilis and Thicken Up
Strain Sweeps (10 rad/s), solids concentration 2.5g/50 ml waterNutilis, Starch plus polymer?
Thicken Up, starch only?
Oscillatory Frequency Sweep Data for Nutilis and Thicken Up
Frequency Sweeps (1% strain), solids concentration 2.5g/50 ml water
Thicken Up, starch only?
Nutilis, Starch plus polymer?
Both viscoelastic fluids
Relaxation Spectrum from ARES Software& G’, G” Predictions
Nutilis, Starch plus polymer?
Note; long relaxation modes
Relaxation Spectrum from ARES Software- Comparison of Nutilis & Thicken Up
Thicken Up, starch only?
Note; long relaxation modes
Variation in Viscosity with Increasing Concentration
Nutilis, Starch plus polymer?
Thicken Up, starch only?
Smoothie !
Extensional Rheometry Results – Xanthan Gum
Xanthan gum: 0.5g in 50 ml water Polymer only
6000 frames per second
Frame: 1 80 131(Piston stops)
400 600 850 860 900
Classic polymer behaviour with long filament decay
Extensional Rheometry Results - Nutilis
Nutilis: 2.5g in 50 ml water, Starch plus polymer? 6000 frames per second
Frame: 1 100 120(Piston stops)
300 480 490 491 500
Unusual collapse due to non homogeneous fluid
Extensional Rheometry Results – Thicken Up
Thicken Up: 2.5g in 50 ml water, Starch only?
6000 frames per second
Filament breakage before pistons completed displacement.
Frame: 1 53 54 100
Unusual collapse due to non homogeneous fluid
The Cambridge Throat– Model Throat
“The Cambridge Throat”
Dialysis tubing is used to
model the mouth
Roller models the tongue
Epiglottis
Oesophagus – food pipe
Airway
Weight provides a constant torque, (stress)
“tongue”
The roller and pulley used to represent the tongue.
Epiglottis
Water
Water
Water
Nutilus, starch plus polymer?
Nutilus, starch plus polymer?
Nutilis Thicken up
Residence time within tube
Time from
Residence time as a function of solids concentration
0.1
1
10
0 2 4 6 8 10
Solids Concentration (wt%)
Residence time (s)
Nutilis
Thicken Up
Xanthan gum
Water
Residence time increases with increasing concentration
Residence time from epiglottis to airway
Time from epiglottis to airway as a function of solids concentration
0.01
0.1
1
10
100
0 1 2 3 4 5 6 7 8 9
Solids Concentration (wt%)
Time (s)
Nutilis
Thicken Up
Xanthan gum
Water
Residence time increases with increasing concentration
Type of Flow
Type of Flow
Constant Stress, Fluid Slug flow
J. Rheol. 484, 765-785 July/August 2004
Arjen C. B. Bogaerds, Martien A. Hulsen,Gerrit W. M. Peters, and Frank P. T. Baaijens
Stability analysis of injection molding flows
Conclusions
• Dysphagia fluids rheologically characterised.• Fluids are highly viscoelastic.• Design and build of “The Cambridge Throat”.• Residence time of fluid strongly dependant on formulation, viscoelasticity may play a role in division of flow between food and airpipe.
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