Miniaturized dynamic light scattering instrumentation for use in microfluidic applications.
Five designs for a miniaturized dynamic light scattering (DLS) instrument are described that incorporate microfluidic flow of the sample volume and fiber optic probes directly embedded into the sample. These instruments were demonstrated to accurately determine the size of 10-100 nm particles dispersed in organic and aqueous solvents with most sample sizes less than 150 microl. Small stir bars were incorporated directly into the instruments, and enabled blending of different solutions immediately prior to DLS measurements. Demonstration of the instruments' capabilities include high throughput measurements of the micelle to unimer transition for poly(styrene-b-isoprene) in mixed toluene/hexadecane solvent, obtained by systematically blending toluene-rich and hexadecane-rich polymer solutions. The critical solvent composition was quickly identified with less than 20 mg of polymer. Further capabilities include temperature control, demonstrated by identification of a critical micelle temperature of poly(ethylene oxide-b-propylene oxide-b-ethylene oxide), as well as multiangle DLS measurements.
Polymers Division, National Institute of Standards and Technology, 100 Bureau Drive Gaithersburg, Maryland 20899-8542, USA.
Thomas Q
TQ
Chastek
Kathryn L
KL
Beers
Eric J
EJ
Amis
D004867:Equipment Design; D019544:Equipment Failure Analysis; D005336:Fiber Optic Technology / Q000295:instrumentation*; D008027:Light; D008832:Microchemistry / Q000295:instrumentation* / Q000379:methods; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation* / Q000379:methods; D008904:Miniaturization; D009391:Nephelometry and Turbidimetry / Q000295:instrumentation* / Q000379:methods; D055100:Optical Fibers; D010783:Photometry / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity