Low-cost laser-cut patterned chips for acoustic concentration of micro- to nanoparticles and cells by operating over a wide frequency range

Abstract

Acoustofluidic platforms for cell manipulation benefit from being contactless and label-free at potentially low cost. Particle concentration in a droplet relies on augmenting spatial asymmetry in the acoustic field, which...

Acoustomicrofluidic Concentration and Signal Enhancement of Fluorescent Nanodiamond Sensors

“…Many studies to date have reported on the efficient manner by which large (micron-sized) particlesprimarily those with relatively low density such as PS particles and cellsare rapidly concentrated in a sessile droplet by the SAW microcentrifugation flow, − as typically shown for 5 μm PS particles in Figure a. On the other hand, the challenges associated with concentrating particles below 1 μmagain, primarily those with relatively low densityunder the same microcentrifugation flow have also been well documented .…”

“…We opt here to adopt an active actuation strategy to avoid the complex and costly nanofabrication of on-chip flow structures and since it allows a higher degree of operational controllability and tunability by varying the external field intensity. Among the various active microcentrifugation schemes that have been reported to date, which also include bulk acoustic wave devices, , surface acoustic waves (SAWs)nanometer amplitude electromechanical Rayleigh waves that propagate along the surface of a piezoelectric substrateand their hybrid surface and bulk wave counterpart, namely, surface reflected bulk waves (SRBWs), have been demonstrated to be particularly adept at driving, among a myriad of microfluidic particle manipulation and flow actuation schemes, − intense microcentrifugation flows by breaking the symmetry of the wave to effect rapid and efficient micromixing and localized particle trapping and concentration − in a completely integrated and portable chipscale device …”

Acoustofluidic localization of sparse particles on a piezoelectric resonant sensor for nanogram-scale mass measurements

“…To realize sessile droplet microcentrifugation to localize scattered particles at the center of the droplet (where the MEMS resonator is located), a spatially asymmetric acoustic field is generated on the SAW transducer (substrate) and coupled into the MEMS chip (superstrate). Three methods for generating asymmetric fields have been reported, the use of f-IDTs in SAW transducer design 19 , the employment of a frequency selective phononic crystal etched into a superstrate 18 , and the use of nonfrequency selective periodic structures patterned in a superstrate 27 . For simplicity of implementation, f-IDTs are utilized in this work.…”

Effect of viscosity on surface acoustic wave driven collective particle dynamics in sessile droplets: nebula, black holes and white dwarfs

“…Particles contactless manipulation such as concentration, aggregation and separation in microfluidics is previously considered to be the result of the combined action of the two forces: acoustic radiation force (F Gov kov ), acoustic streaming drag force (F D ) or tea leaf effect [1][2][3]. However, it is unlikely to be due to the radiation force because similar phenomena can be observed without acoustic field, which can reference the study of Yeo et al [4].…”

“…As pointed out by the title of Yeo et al [4], the microfluidic version is simply an analogy. Indeed, gravity scales as d 3 p and the drag force scales as d p . Therefore, if the tea leaf experiment had to be repeated 10 µm particles (1000 times smaller than a small tea leaf), the density difference with water would need to be 1,000,000 times larger to hold the spheres in place.…”