Ultrasonic particle concentration in a line-driven cylindrical tube

Abstract

Acoustic particle manipulation has many potential uses in flow cytometry and microfluidic array applications. Currently, most ultrasonic particle positioning devices utilize a quasi-one-dimensional geometry to set up the positioning field. A transducer fit with a quarter-wave matching layer, locally drives a cavity of width one-half wavelength. Particles within the cavity experience a time-averaged drift force that transports them to a nodal position. Present research investigates an acoustic particle-positioning device where the acoustic excitation is generated by the entire structure, as opposed to a localized transducer. The lowest-order structural modes of a long cylindrical glass tube driven by a piezoceramic with a line contact are tuned, via material properties and aspect ratio, to match resonant modes of the fluid-filled cavity. The cylindrical geometry eliminates the need for accurate alignment of a transducer/reflector system, in contrast to the case of planar or confocal fields. Experiments show that the lower energy density in the cavity, brought about through excitation of the whole cylindrical tube, results in reduced cavitation, convection, and thermal gradients. The effects of excitation and material parameters on concentration quality are theoretically evaluated, using two-dimensional elastodynamic equations describing the fluid-filled cylindrical shell with a line excitation.

Flow cytometry: retrospective, fundamentals and recent instrumentation

“…This hydrodynamic focusing results from several stability developments (Steen 1990), and is used in most flow cytometers. However, other focus concepts exist, such as microcapillary technology or acoustic focusing (Ward et al 2009) which allows alignment of cells by sound waves (Goddard et al 2006(Goddard et al , 2007Goddard and Kaduchak 2005) without damage to cells (as ultrasound for fetus in utero medical exam).…”

“…Since 2010, Life technologies TM Corporation proposes an acoustic focusing analyzer that uses sound waves to precisely control cell movement (Goddard and Kaduchak 2005;Goddard et al 2006Goddard et al , 2007. Attune TM equipped with a 50 mW 405 nm and 20 mW 488 nm solid-state lasers, analyzes FSC, SSC and six colors.…”

Microscale acoustofluidics: Microfluidics driven via acoustics and ultrasonics

“…Goddard and Kaduchak (2005) demonstrated a method for concentrating particles along a single line through precise control of the acoustic wave in a small cylindrical tube, reminiscent of the work by Vainshtein et al (1996) some 10 years prior, and representative of the many ideas for particle manipulation appearing in the literature in combination with microfluidics. As one of the earliest combinations of acoustic energy and microfluidics for manipulating particles in a closed system known to us, Kaajakari et al (2001) made a broad-based attempt to mix and pump fluids and manipulate suspended particles within.…”

“…A relatively early study by Kumar et al (2005) reported the acoustic separation of hybridoma and lactobacillus using ultrasound irradiation perpendicular to the main axis of flow, with modest efficiency and flow rate. Goddard and Kaduchak (2005) used ultrasound to focus 10 m particles and cells in a 190 mm long glass capillary tube with an inner diameter of 1.9 mm along a 14 mm long region exposed to acoustic radiation at 417 kHz from a pair of PZT transducers attached to either side of the tube. They were able to focus the objects to within a 40 m region at the center of the flow using this configuration with nearly 100% concentration efficiency.…”

A thin-reflector microfluidic resonator for continuous-flow concentration of microorganisms: a new approach to water quality analysis using acoustofluidics

“…44,45 Based on this functioning principle, concentration of a range of particles including bacterial spores, biological cells and polystyrene spherical micro-beads has been demonstrated. 15,38,[46][47][48][49][50][51] Nordin and Laurell have recently demonstrated a very significant increase in concentration of red blood cells and prostate cancer cells (up to a maximum of ~200-fold), using a two-stages half-wavelength resonator. 15 However, direct manipulation of bodies as small as bacteria by means of ARFs represents a considerable physical challenge.…”