Experimental Study of Flow in Micropipette

Abstract

Micropipette injection has wide applications in genetic, physiological, pharmacological and micro-chemical research at pico-liter or sub-pico liter level. Micropipettes are generally tapered glass tubes with the inner exit diameter of 0.2 to a few microns. The quantitative relationship describing the injection volume and the operational parameters and pipette geometry in the microinjection process, however, has never established. This paper experimentally studied the injection flow rate as a function of injection pressure as well as the pipette geometry and fluid properties for the hydrophilic glass surface. It was found that the experimental pressure drop for the pressure-driven flow was always less than that was predicted by the classical theory with no slip boundary conditions. A model with slip boundary condition was developed for the axisymmetric conical flow and the result agreed well with computational simulation with slip boundary and the experimental data. The analysis indicated that the slip length was about 0.12 μ for water flow through micropipette of exit diameter 0.94 ~ 4.48 μm, half cone angle 3.3 ~ 5.2°, surface roughness 2.1 ~3.8 nm with shear rate ranging from 106 to 107 s-1.

Optimization of micropipette fabrication by laser micromachining for application in an ultrafine atmospheric pressure plasma jet using response surface methodology

“…A glass micropipette fabricated by a micropipette puller with a tapered end has attracted considerable attention in various applications. Because small amounts of DNA fragments, fluorescent substances, or specific proteins can be injected into tissues or cells this way, it has been widely used in the applications of genetic, physiological, pharmacological and micro-chemical fields [1][2][3][4]. Moreover, due to their convenient preparation and low-cost fabrication, more and more glass micropipettes, with a tip diameter ranging from nanometers to micrometers, are being used for the atmospheric pressure micro-plasma generators in cancer therapies [5], material functionalization [6][7][8] and material micro-etching [9][10][11][12][13].…”

Optimized fabrication of micropipette using laser micromachining process and application in functional electrical stimulation of muscle tissue

“…It can be acted as the fluid microtubule because of smooth pipe wall, convenient preparation and low cost fabrication [1]. Moreover, its fluid resistance is smaller than one of the rectangular cross-section microtubule made of silicon [2][3][4].…”