Poly(dimethylsiloxane) microchip: microchannel with integrated open electrospray tip

Abstract

A polymer microchip with an open tip for electrospray mass spectrometry is presented. The tip consists of a groove with parallel walls where a droplet can form at the end surface. A lid covers the whole chip except at the microchannel tip, which is left open. Poly(dimethylsiloxane) (PDMS) microchips were cast using a nickel mould which in turn was replicated from a dry etched silicon wafer. Tips with microchannel widths of around 50 microm could easily be replicated. Since the tip had no cover, the assembly of microchip and cover was simplified. A total ion current variation of 5% during 300 s was achieved for a 1 microM myoglobin solution. The non-complex design of the cover makes it suitable for versatile tests of chip prototypes. The nickel mould was found to be useful for PDMS microstructure fabrication. Also, such a robust mould allows casting electrospray tips in more rigid thermoset materials.

Thin chip microsprayer system coupled to quadrupole time-of-flight mass spectrometer for glycoconjugate analysis

“…The potential of these modern systems is considerably broadening the area of MS applicability in life sciences. The option of miniaturized devices for sample infusion into MS is driven by several technical, analytical and economical advantages such as: (1) simplification of the laborious chemical and biochemical strategies required currently for MS research; (2) high throughput nanoanalysis/identification of biomolecules; (3) elimination of the time-consuming optimization procedures; (4) an increase in the sensitivity by drastic reduction of the sample and reagent consumption, sample handling and potential sample loss; (5) high reproducibility of the experiments; (6) the potential to discover novel biologically-relevant structures due to increased ionization efficiency; (7) high signal-to-noise ratio; (8) reduced in-source fragmentation leading to a significant increase of the precision in the identification of unknown analytes in biological matrices; (9) flexibility and a broad area of applicability; (10) low cost of analysis and chip production; (11) the possibility for unattended high-throughput experiments reducing man power and intervention; (12) elimination of possible crosscontamination and carry-overs; (13) flexibility for different configurations and analyses, upgrading and modifications; (14) minimal infrastructure requirements for optimal functioning; (15) reduction of the ion source size facilitating manipulation and efficient ion transfer by precise positioning towards the MS sampling orifice.…”

“…[13][14][15] Different MS configurations [16][17][18][19] such as single and triple quadrupole MS ion trap and ultra high resolution Fourier-transform ion cyclotron resonance mass spectrometry (FTICR MS) were adapted to polymer-based chip ESI interfacing and optimized mostly for proteomic surveys.…”

An open design microfabricated nib-like nanoelectrospray emitter tip on a conducting silicon substrate for the application of the ionization voltage

“…"Needle-like" approaches were reported using silicon nitride [11], parylene [12], silicon [13][14][15], as well as polycarbonate [16] or polymethyl methacrylate (PMMA) [17]. The reported "channel-like" approaches include PMMA starshaped systems [18], polydimethyl siloxane (PDMS) devices having a triangular shape [19], devices based on a groove feature [20], machined point-like structures [21], polyimide-based triangular systems [22], and triangular parylene sheet-based devices [23].…”

On-Line High-throughput ESIMS Detection of a Reaction Product Using Synthesis and Extraction Microchips

“…28) The second is to fabricate a nanospray nozzle on the microchip. 29), 30) In the first method, the connection devices are easy to construct, and it is also easy to exchange the transfer capillary or the nanospray tip if their insides are clogged. However, in this approach, avoiding a dead volume at the interface between the microchip and the spray tip may be di$cult.…”