Technique for mechanical measurements using optical scattering from a micropipette [cells application]

Abstract

This communication proposes an optical method using forward light scattering to measure the deflection of a micropipette from a normal contact force with a small elastic solid, and the damping coefficient of a small fluid sample through a dynamic interaction with the pipette. An analytical and experimental study of this sensor is performed and described for each property. Topics covered include: 1) forward light scattering technique for determining the diameter of a micropipette (using exact and simplified geometric interference theories); 2) deflection measurement and analysis on the pipette-sample system using the finite element method; and 3) equivalent damping coefficient and resonant frequency measurement of the pipette-fluid system and its numerical solution derived from the finite element model. A comparison of the experimental results and the analytical results is included to provide the means for analyzing the potential of this new method.

Fluid viscosity measurement using forward light scattering

“…To measure fluid viscosity we extend the technique developed by Wang et al [6,7]. A diagram of the experimental system is shown in figure 1(a).…”

“…] which can be further approximated by keeping first term of the expansion, C f = (4π 3 f D 2 µρ l ) 1/2 . The fluid damping then becomes proportional to the square root of the viscosity µ [6,7,11]. Based on the fluid damping coefficient, and neglecting the structural damping of the fibre, the peak vibration amplitude, Z max , of a partially submerged fibre is…”

“…Optical techniques for viscosity measurement were not extensively explored until the recent development of an optical method utilizing a forward light scattering pattern as an indirect measurement of fluid viscosity by Wang et al [6,7]. The fluid viscosity was derived from the damping of an immersed vibrating micro-pipette.…”

Development of an experimental technique for testing rheological properties of ultrathin polymer films used in nanoimprint lithography

“…3 Professor Isrealachvili has developed a surface force apparatus which also can be used to measure the viscosity of thin films, 4,5 and there are many improvements of this method. [6][7][8][9] There is a wide variety of acoustic and optical methods of viscosity measurements, [10][11][12][13][14][15][16][17][18][19][20][21] and a very interesting method of viscosity measurement which uses nanoindentation. 22 This last method was particularly interesting because the samples studied were nanoimprint resists.…”