Paper-Based Microfluidic Surface Acoustic Wave Sample Delivery and Ionization Source for Rapid and Sensitive Ambient Mass Spectrometry

Abstract

A surface acoustic wave-based sample delivery and ionization method that requires minimal to no sample pretreatment and that can operate under ambient conditions is described. This miniaturized technology enables real-time, rapid, and high-throughput analysis of trace compounds in complex mixtures, especially high ionic strength and viscous samples that can be challenging for conventional ionization techniques such as electrospray ionization. This technique takes advantage of high order surface acoustic wave (SAW) vibrations that both manipulate small volumes of liquid mixtures containing trace analyte compounds and seamlessly transfers analytes from the liquid sample into gas phase ions for mass spectrometry (MS) analysis. Drugs in human whole blood and plasma and heavy metals in tap water have been successfully detected at nanomolar concentrations by coupling a SAW atomization and ionization device with an inexpensive, paper-based sample delivery system and mass spectrometer. The miniaturized SAW ionization unit requires only a modest operating power of 3 to 4 W and, therefore, provides a viable and efficient ionization platform for the real-time analysis of a wide range of compounds.

Microscale acoustofluidics: Microfluidics driven via acoustics and ultrasonics

“…V. Ohno et al (2008) presented a review of microfluidics as applied to analytical chemistry and biochemistry, and Salieb-Beugelaar et al (2010) provided a recent review of microfluidics applied to cellular biology, both from the same group that established microfluidics thinking in this same area some 10 years prior; Meyvantsson and Beebe (2008) provided a thorough review on the application of microfluidics to cell culture. Ho et al (2011) provided a comprehensive and broad review of laboratory and consumer biotechnological applications emerging from the past decade of microfluidics. Teh et al (2008) covered a particularly interesting aspect of microfluidics in association with acoustics: drop microfluidics.…”

“…Circumventing the limitations of current microfluidics technology is indeed critical to delivering on its idyllic promises (Ho et al, 2011), from handheld medical diagnostic devices for the rapid detection of single molecules associated with heart disease (Gerszten and Wang, 2008), cancer (Lu et al, 2005), and physiological fluid chemistry (Craighead, 2006), to water purification (Shannon et al, 2008) and polymerase chain reaction on a chip (Huang et al, 2006). Fortunately, acoustic wave technology at the microscale to nanoscale is helping to make these things reality, as will be shown, and furthermore promises to allow researchers to produce and exploit interesting physical phenomena seen at the microscale-to-nanometer scale.…”

Future microfluidic and nanofluidic modular platforms for nucleic acid liquid biopsy in precision medicine

“…[147][148][149][150][151][152] For example, we can pack 25 nm to 100 nm oligo-functionalized Au, silica and polystyrene NPs into iontrack etched polyethylene terephthalate (PET) polymer conic nanopores, 134,135 and into conic silica nanocapillaries pulled by laser assisted drawing. 130,136,137 We have studied the NP assembly mechanism with two-dimensional nano-wedge models fabricated by focused ion beam milling.…”

Surface acoustic wave electric field effect on acoustic streaming: Numerical analysis

“…In Ref. 57, the SAW accompanying electric field is used in a mass spectrometer involving a SAW-chip. The electric field accompanying the SAW polarizes the liquid, forming ions.…”