Using acoustic radiation force as a concentration method for erythrocytes

Abstract

We investigated the potential damage inflicted on erythrocytes by acoustic radiation force when the cells are concentrated by a 500-kHz ultrasonic standing wave at the pressure node. The extent of the damage was estimated from the concentrations of potassium ions, iron complexes, and lactate dehydrogenase released from the cells. After 2 min of ultrasound irradiation at 12.8 mJ/m3, the cells concentrated on the pressure node, with a cell distribution half-width of 138 microns; no significant release of intracellular components was detected, even after 15 min of irradiation. The results indicate that even small ions like potassium are not released as a result of ultrasound irradiation on cell membranes without cavitation, and they demonstrate the potential use of acoustic radiation force for concentrating living cells in biomedical applications.

Microscale acoustofluidics: Microfluidics driven via acoustics and ultrasonics

“…Despite this, the absence of cavitation allowed the cells to remain whole and damage free based on the standards defined by Yasuda et al, who made this judgement solely on the presence of lysis products in the surrounding fluid. Spengler et al (2000) observed the rather more general agglomeration of yeast cells in a small 60', 15 Â 5 Â 0:8 mm fluid chamber with thickness sized to accommodate one wavelength of the vibration at 1.9 MHz [with a configuration somewhat similar to Yasuda et al (1997)], and found the yeast cells collected at pressure nodes defined in a way that indicates the presence of Schlichting streaming in their study. Takeuchi and Yamanouchi (1994) reported what is believed to be the earliest use of SAW to collect particles in fluid, using a pair of Rayleigh SAW devices of 128YX LN, each with a floating electrode IDT and dipped as probes into a thin water film.…”

“…Although the lateral forces on particles from acoustic irradiation had been known to exist as a weak force, they quantified the force for the purposes of sorting cells. The same year, Yasuda et al (1997) demonstrated the ability to separate (guinea pig) erythrocytes at a hematocrit of 3.3%, about an order of magnitude lower concentration than human blood (with a typical hematocrit of around 35%-50%). Using 500 kHz ultrasound in a thicknessmode, pistonlike vibration for 1-2 min, they were able to concentrate the erythrocytes along a 150-m-thick region midway between the transducer faces on the top and bottom of the 800 m thick chamber, despite the fact the erythrocytes red blood cell (RBC) have only a slightly larger density than the surrounding fluid ( RBC % 1099 kg=m 3 ).…”

“…By doing so, the hours-long tedium of gravity-driven perfusion of stem cells into supporting scaffold structures for tissue engineering is reduced to a few seconds. In contrast to the rather direct and simple approach adopted by Yasuda et al (1997) a decade earlier, Li et al (2009) studied the functionality of stem cells exposed to 20 MHz SAW over an extended period to determine whether exposure to intense SAW radiation might leave such cells alive but 330mW, 10 5 particles/ml 330mW, 10 6 particles/ml 330mW, 10 7 particles/ml 510mW, 10 5 particles/ml 120mW, 10 5 particles/ml dysfunctional. They took fluorescence labeled osteoblast cells, and drove them into polycaprolactone porous scaffolds and found over 80% of the cells to be viable and functional: They were able to generate hydroxyapatite at the same rate as control samples of the cells not exposed to SAW.…”

Characteristics of Particle Separation in Suspension using an Ultrasonic Standing Wave

“…During the process, due to conflicting compression of erythrocytes and lipids, erythrocytes were gathered towards the pressure nodes, while lipids were aggregated towards the anti-pressure nodes. Yasuda et al (1997) attempted to concentrate erythrocytes inside blood at the pressure nodes in a 500 kHz ultrasonic standing wave, while Zhou et al (1998) were able to improve the detection performance of sensors by concentrating Salmonella in the suspension towards the pressure nodes in the same 500 kHz ultrasonic standing wave. Pui et al (1995) has developed a cell harvesting system by using an ultrasonic standing wave to align and aggregate cells, and then making them precipitate by gravity.…”

“…They reported that acoustic pressure was mainly affected by reflector thickness, channel width, and excitation frequency, and it was effective when the channel width was determined as an integer multiple of the half wavelength. Yasuda et al (1997) has adopted an ultrasonic standing wave generation method, by exciting an ultrasonic wave simultaneously at both ends of a half-wavelength chamber. It took 2 minutes to concentrate erythrocytes towards the pressure nodes under an acoustic radiation force of 12.8 mJ/m 3 ; the suspension temperature increased from 20°C to 35°C within 8 minutes of ultrasonic oscillation.…”