Image Analysis: Evaluating Particle Shape

5,682 views

Published on

Dr. Jeff Bodycomb of HORIBA Particle discusses how image analysis technologies can be used to measure particle shape parameters.

This presentation is archived with the original webinar video in the Download Center at www.horiba.com/us/particle.

Published in: Technology, Business
1 Comment
4 Likes
Statistics
Notes
No Downloads
Views
Total views
5,682
On SlideShare
0
From Embeds
0
Number of Embeds
10
Actions
Shares
0
Downloads
173
Comments
1
Likes
4
Embeds 0
No embeds

No notes for slide
  • Line joining feret tangent points
  • There are different presentations of shape distributions known: the most popular is amount by size (sieving). The CAMSIZER expands this by a third axis: Shape. Now it is additionally possible to determine shape by size, or amount by shape.
  • Here an example for 2 different particle shapes and a mixture of them (waterfilter: ion - exchanger (B) and charcoal (A)): The parameters with the highest difference between curve A and B (perpendicular arrows) result in a threshold which can be entered in the CAMSIZER software. Black and green => pure materials blue => mixture Best parameter b/l Best threshold b/l = 0.9
  • Afterwards the software can show the precise amounts of A or B inside the mixture. here: A -> 67,2 % or B -> 32,8 % Shape analysis for: shape determination for product quality and process control. Shape thresholds for determination the amount of components of a mixture. Shape thresholds for determination the amount of broken particles.
  • Image Analysis: Evaluating Particle Shape

    1. 1. Image Analysis: Evaluating Particle Shape Jeffrey Bodycomb, Ph.D. HORIBA Scientific www.horiba.com/us/particle
    2. 2. Why Image Analysis? <ul><li>Verify/Supplement diffraction results (orthogonal technique) </li></ul><ul><li>Replace sieves </li></ul><ul><li>Need shape information, for example due to importance of powder flow </li></ul>These may have the same size (cross section), but behave very differently.
    3. 3. Why Image Analysis? <ul><li>Crystalline, acicular powders needs more than “equivalent diameter” </li></ul>We want to characterize a needle by the length (or better, length and width).
    4. 4. Why Image Analysis <ul><li>Pictures: contaminants, identification, degree of agglomeration </li></ul><ul><li>Screen excipients, full morphology </li></ul><ul><li>Root cause of error (tablet batches), combined w/other techniques </li></ul><ul><li>Replace manual microscopy </li></ul>
    5. 5. Why Shape Information? <ul><li>Evaluating packing </li></ul><ul><li>Evaluate flow of particles </li></ul><ul><li>Evaluate flow around particles </li></ul><ul><li>Retroreflection (optical properties) </li></ul><ul><li>Properties of particles in aggregate (bulk) </li></ul>
    6. 6. Effect of Shape on Flow <ul><li>Yes, I assumed density doesn’t matter. </li></ul><ul><li>Roundness is a measure based on particle perimeter. </li></ul> c
    7. 7. Major Steps in Image Analysis Image Acquisition and enhancement Object/Phase detection Measurements
    8. 8. Two Approaches Dynamic: particles flow past camera Static: particles fixed on slide, stage moves slide 1 – 3000 microns 0.5 – 1000 microns 2000 microns w/1.25 objective
    9. 9. Size Parameters -> Shape Parameters Shape parameters are often calculated using size measures
    10. 10. Size Parameters <ul><li>Feret </li></ul><ul><ul><li>Max (length) </li></ul></ul><ul><ul><li>Perpendicular to Max (width) </li></ul></ul><ul><ul><li>Min (width) </li></ul></ul><ul><ul><li>Perpendicular to Min (main length) </li></ul></ul><ul><li>Area </li></ul><ul><ul><li>Circular Diameter </li></ul></ul><ul><ul><li>Spherical Diameter </li></ul></ul><ul><li>Perimeter </li></ul><ul><li>Convex Perimeter </li></ul>
    11. 11. Ferets <ul><li>Size as measured with a caliper </li></ul><ul><li>Result depends on orientation of caliper </li></ul><ul><ul><li>Min </li></ul></ul><ul><ul><li>Max </li></ul></ul><ul><ul><li>Perpendicular to Min </li></ul></ul><ul><ul><li>Perpendicular to Max </li></ul></ul> to Max Max Min  to Min
    12. 12. Area (Circular Diameter) <ul><li>Count pixels to find area of particle </li></ul><ul><li>Convert to circle with equivalent area </li></ul>Diameter same AREA
    13. 13. Perimeter, Convex Perimeter <ul><li>Perimeter follows exact contours of object </li></ul><ul><li>Convex perimeter is like a rubber band. </li></ul>
    14. 14. Shape Descriptors <ul><li>aspect ratio </li></ul><ul><li>roughness </li></ul><ul><li>roundness </li></ul><ul><li>sphericity </li></ul>
    15. 15. Shape Using a Chart Krumbein, Journal of Sedimentary Petrology, vol 11, no 2, pp 64-72, plate 1, August, 1941
    16. 16. A different chart <ul><li>Compare particles to a chart like the one below. </li></ul>Round corners Overall shape like a sphere
    17. 17. Aspect Ratio <ul><li>Length of longest Feret over Length of shortest Feret </li></ul><ul><li>Longest Feret over Feret perpendicular to longest Feret </li></ul><ul><li>Feret perpendicular to shortest Feret over shortest Feret </li></ul><ul><li>Or their reciprocal! </li></ul><ul><li>Nice measure of deviation from roundness. Is not profoundly affected by bumps on particle surface. </li></ul><ul><li>Measures “large scale shape” </li></ul>
    18. 18. Aspect ratios of square 1 1 Fe Max is diagonal: 1.414 Perp to Fe Max is diagonal: 1.414 Fe Min is 1 Fe Max / Fe Min = 1.414/1 = 1.414 Fe Max / Perp to Fe Max = 1.414/1.414 = 1 Perp to Fe Min / Fe Min = 1/1 = 1
    19. 19. Salt Shape in Aluminum Foam <ul><li>NaCl is used to manufacture aluminum foams as a filler. The NaCl is subsequently dissolved away to leave a porous structure. </li></ul><ul><li>The shape and size of the NaCl affects the foam structure and the final properties of the foam. </li></ul>C. Gaillard, J. F. Despois and A. Mortensen Processing of NaCl powders of controlled size and shape for the microstructural tailoring of aluminium foams Materials Science and Engineering A Volume 374, Issues 1-2, 15 June 2004, Pages 250-262 Image courtesy of Wikimedia Commons User Stehfun
    20. 20. NaCl Shape HORIBA Application Note AN189: size and Shape Analysis of Salt using Dynamic Image Analysis
    21. 21. Glass beads for reflective pavement marking <ul><li>Beads must be round to reflect light back to driver. </li></ul><ul><li>Check aspect ratio of each particle, fail if too many particle have a value that is too low. </li></ul>HORIBA Application Note AN140: Particle size and Shape analysis of glass beads for pavement markings Aspect ratio 0.5051 Aspect ratio 0.9660
    22. 22. Acetaminophen (API)
    23. 23. Roughness <ul><li>Jaggedness of edges </li></ul><ul><li>Short scale. Roughness is sensitive to bumps on surface </li></ul><ul><li>As surface has more concavities, the convex perimeter increases and therefore roughness decreases </li></ul>
    24. 24. Roundness <ul><li>As particle becomes circular, value approaches one. </li></ul>Length
    25. 25. Roundness of metal particles <ul><li>Metal particles are used for powder metallurgy </li></ul><ul><li>Round particles flow better (e.g., during injection molding) and provide stronger parts </li></ul>Low quality nickel alloy powder. Note the small fraction of very round particles HORIBA Application Note AN164: Particle Size and Shape Analysis of Metal Powders
    26. 26. Pharmaceutical Globules <ul><li>Spheres from sugar are often used. </li></ul><ul><li>Shape matters for future process steps </li></ul><ul><ul><li>incorporation or coating of API’s </li></ul></ul><ul><ul><li>Flow through dispensers </li></ul></ul>HORIBA Application Note AN140: Particle size and Shape analysis of glass beads for pavement markings
    27. 27. Acetaminophen (API)
    28. 28. Sphericity <ul><li>As particle becomes spherical, value approaches one. </li></ul><ul><li>More sensitive to small scale bumps that increase perimeter than roundness. </li></ul>
    29. 29. Circularity, Sphericity, Perimeter, Diameter area of the particle perimeter of the particle circle with same area as particle diameter of circle of same area Circularity = perimeter of circle / perimeter of particle Sphericity = Circularity 2 = A green ~ 77 pixel, diameter red = 10 pixel, perimeter green ~ 38,5 pixel, circularity ~ 31 / 38,5 = 0.81 , sphericity = 4 * π * 77 / (38.5) 2 = 0.81 2 = 0.65 A particle is inside of particle perimeter
    30. 30. Proppants <ul><li>Hold open cracks in oils wells to allow oil to flow to well (Hydraulic Fracturing). </li></ul><ul><li>Sand is one example of a proppant </li></ul><ul><li>High roundness and sphericity leads to better permeability. </li></ul><ul><li>ISO/DIS 13503-2 recommended sphericity and roundness of 0.6 or greater, 0.7 for high strength materials. </li></ul><ul><li>Note that these definitions of sphericity and roundness are different from, but related to the one’s used in this talk. </li></ul>
    31. 31. Distributions <ul><li>Just like size, many particle samples have a distribution of shapes. </li></ul><ul><li>Sometimes a distribution of shapes is desirable. For example, according to the USGA, sand that is highly uniform in size and shape tends to be less stable. Therefore, sand with a variety of grain sizes and shapes is better for use in sand traps. </li></ul>http://www.usga.org/course_care/articles/construction/bunkers/How-to-Select-the-Best-Sand-for-Your-Bunkers/
    32. 32. Size- & Shape Results Measurement Results size amount <ul><li>size + size distribution </li></ul><ul><li>- amount by size </li></ul>shape <ul><li>shape + shape distribution </li></ul><ul><li>- shape by size </li></ul>- amount by shape shape
    33. 33. Sorting Roughness, “too rough” is red Roundness, not round enough is green
    34. 34. Particle Shape: A mounts in a Mixture Measurement Results B A B A
    35. 35. Particle Shape: A mounts in a Mixture Measurement Results Q 3 (round particles) = 32.8% 67.2% x Fe max x c min
    36. 36. The HORIBA PSA300 <ul><li>Turnkey System </li></ul><ul><ul><li>More time getting results and less time engineering </li></ul></ul><ul><li>Automated </li></ul><ul><ul><li>Faster </li></ul></ul><ul><ul><li>Less operator labor </li></ul></ul><ul><ul><li>Less operator bias </li></ul></ul><ul><li>Powerful Software Features </li></ul><ul><ul><li>Image Enhancement </li></ul></ul><ul><ul><li>Particle separation </li></ul></ul><ul><li>Separate Disperser Option </li></ul><ul><ul><li>More flexible sample preparation </li></ul></ul>
    37. 37. Static or Dynamic Image Analysis? <ul><li>Dynamic </li></ul><ul><ul><li>Broad size distributions (since it is easier to obtain data from a lot of particles) </li></ul></ul><ul><ul><li>Samples that flow easily (since they must be dropped in front of camera) </li></ul></ul><ul><ul><li>Samples tumble so sometimes you see more orientations </li></ul></ul><ul><ul><li>Powders, pellets, granules </li></ul></ul><ul><li>Static </li></ul><ul><ul><li>Samples that are more difficult to disperse (there are more methods for dispersing the samples) </li></ul></ul><ul><ul><li>Samples that are more delicate </li></ul></ul><ul><ul><li>Pastes, sticky particles, suspensions </li></ul></ul>
    38. 38. Conclusions <ul><li>Image Analysis is good for </li></ul><ul><ul><li>Size </li></ul></ul><ul><ul><li>Shape </li></ul></ul><ul><ul><li>Supplementing other techniques </li></ul></ul><ul><li>Shape Analysis is the next step beyond size </li></ul><ul><ul><li>Choice of parameters is very application dependent. </li></ul></ul>
    39. 39. Questions? www.horiba.com/us/particle Jeffrey Bodycomb, Ph.D. [email_address] 866-562-4698

    ×