Measuring Fluid Properties on a Microscopic Scale Using Optically Trapped Microprobes. Mark Cronin-Golomb Biomedical Engineering Tufts University. With the help of:. Boaz Nemet Yossef Shabtai Lisa Goel at Tufts University Tayyaba Hasan Paal Selbo
at Tufts University
at Wellman Laboratories of Photomedicine, MGH
M.T. Valentine, L.E. Dewalt & H.D. OuYang, “Forces on a colloidal particle in a polymer solution: A study using optical tweezers.” Journal of Physics-Condensed Matter8, 9477-9482 (1996).
x: trap positiong: viscous drag
k: tweezer spring constant a: amplitude of trap oscillation
w: frequency of trap oscillation L(t): Brownian forcing function
Harmonic phase (deg)
Harmonic amplitude (a.u)
Relative Position Detection lags behind.
Absolute Position DetectionSignal to Noise Ratio
New microfluidic devices are being constantly developed. Their fluid dynamics need to be understood.
After A. D. Stroock, S. K. W. Dertinger, A. Ajdari, I. Mezi, H. A. Stone, G. M. Whitesides, Science 295, 647 (2002)
Flow Off lags behind.
Comparison of tweezer and video velocity measurement lags behind.
Note offset induced by Brownian motion of probe bead
Flow scale bar mm / sec
Photodynamic Therapy (PDT) is frequently extremely effective in controlling the primary malignancy, but have also been associated with an increase in distant metastasis.
PDT, used as clinical cancer therapy worldwide, is a method in which photosensitizers (PS) are administered to tumor cells and are activated by light at the appropriate wavelength, where a combination of light, oxygen, and PS are toxic to tumors.Use To Study Effects Of Photodynamic Therapy On Adhesive Properties Of Cancer Cells
Tayyaba Hassan and Paal Selbo, Wellman Lab MGH
E-Cadherin/Catenin Complex Overview in controlling the primary malignancy, but have also been associated with an increase in distant metastasis.