Recent developments in detection methods for microfabricated analytical devices

Abstract

Sensitive detection in microfluidic analytical devices is a challenge because of the extremely small detection volumes available. Considerable efforts have been made lately to further address this aspect and to investigate techniques other than fluorescence. Among the newly introduced techniques are the optical methods of chemiluminescence, refraction and thermooptics, as well as the electrochemical methods of amperometry, conductimetry and potentiometry. Developments are also in progress to create miniaturized plasma-emission spectrometers and sensitive detectors for gas-chromatographic separations.

A nanoporous optofluidic microsystem for highly sensitive and repeatable surface enhanced Raman spectroscopy detection

“…[6][7][8][9] In contrast to fluorescence-based detection, SERS detection produces a fingerprint spectrum of the detected analyte, which enables molecules to be detected without labelling. Furthermore, this narrowband spectral fingerprint enables multi-analyte detection with a single laser source and filter set, 10 which is generally not feasible using fluorescence detection. Nonetheless, SERS continues to be limited to applications in research labs today.…”

“…However, in the case of SERS, this can hurt the detection limit as compared to conventional techniques because of the reduced sample volume and the diffusion-limited transport of analyte molecules within the channel. 10,11 To overcome these barriers, a number of reports have demonstrated improved performance of SERS in microsystems by leveraging the principles of optofluidics, which is defined by the synergistic integration of photonics and microfluidics. [12][13][14][15] In one example of an optofluidic SERS technique, photonic crystal waveguides maximize the interaction of the excitation laser light with nanoparticle-analyte conjugates.…”

High‐resolution electrophoretic separation and integrated‐waveguide excitation of fluorescent DNA molecules in a lab on a chip

“…Capillary electrophoresis (CE) separation is a powerful method over a broad range of molecular sizes, thanks to flexible MF protocols, exploiting a variety of sieving gel matrices. The inherent advantages of MF CE, high-speed operation and low reagent volumes, can be combined with laser-induced fluorescence (LIF) detection [6][7][8] Furthermore, the spatio-temporal resolution provided by integrated waveguide excitation 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 F o r P e e r R e v i e w 4 can allow for a 20-fold improvement in accuracy if better MF CE separation protocols become available.…”

Unconventional detection methods for microfluidic devices

“…The focus will be on work published in the last 2 years and this review is not inferred to be comprehensive. The methods we term as "conventional" -LIF, all electrochemical (EC) detection methods (amperometric, conductivity, potentiometry), and MS -will not be covered here and the reader is referred to several general microfluidic review articles covering these [8][9][10][11][12], as well as many reviews that focus entirely on detection [13][14][15].…”