The present invention relates to the field of microelectromechanical systems (MEMS) research, and particularly relates to a MEMS two-dimensional air amplifier device for electrospray ion focusing.
In recent years, substantial amount of research work has been done in order to improve the sensitivity and resolution of the electro spray mass spectrometry (ESI-MS). The key technology is how to enhance the transmission efficiency of sampling ion generated by ESI and transferred into the mass spectrum more effectively. The air amplifier is an aerodynamics device, which focuses ions into the inlet of MS using Coanda effect and Venturi effect.
The working process of the air amplifier can be described as follows. The gas enters into the chamber from the inlet, and the gas was extruded in the gap and its velocity is increased. The gas moves along the wall by the Coanda effect and a pressure drop generated by the high speed gas velocity occurs due to the Venturi effect, which induces the airflow around the wall surface. The ion plume is focused and speeded up in the center area of the ion focusing groove. Therefore, the transmission efficiency is improved in this way.
People have studied the role of commercial air amplifier in electrospray mass spectrometry system, which can improve the quantity of ions. However, there are disadvantages of the commercial air amplifier such as the large size, complication structure and high cost. These disadvantages are not favorite for the miniaturization of the ESI-MS system and not suitable for the nano-ESI source.
This invention offers a solution to the technical problems of the commercial air amplifier, such as the non-optimized large dimension structure, complicated structure and high cost. This invention provides a fabricated method for a MEMS 2D air amplifier ion focusing device with low cost and simple structure.
A MEMS 2D air amplifier ion focusing device is consist of a chamber structure and a glass substrate. There is an original gas inlet formed in the glass supporting substrate and the body chamber. There is a gap structure at the gas inlet of the chamber. The gas outlet connects with the wall structure. There is also a center area of the ion focusing groove in the axis of air amplifier.
The said original gas inlets are set in the both sides of axis of the said MEMS 2D air amplifier ion focusing device. It could have one or more original gas inlets per side with the same number of original gas inlets for both sides.
The said gap structure can be any angle with the axis of amplifier in the said MEMS 2D air amplifier ion focusing device
The said wall surface structure can be consisted by a smooth plane or a curveded surface in the said MEMS 2D air amplifier ion focusing device.
The said gap structure and the wall surface structure can be connected by a transition curveded surface in the said MEMS 2D air amplifier ion focusing device.
The said structure of the center area of the ion focusing groove can be rectangle or any other shapes. Also, it is always set between amplifier's wall surfaces in the said MEMS 2D air amplifier ion focusing device
The said glass substrate can be polymer, silicon or ceramic materials in the said MEMS 2D air amplifier ion focusing device
The micromachining processing of the said MEMS 2D air amplifier ion focusing device is shown as follows:
(1) The fabrication of 2D air amplifier mold includes two photolithography steps:
The first photolithography: to oxidize a layer of silicon dioxide on silicon wafer. Then, spin coat a layer of photoresist with 150 μm thick followed by a prebake step. Make two mask plates. There is the wall pattern of amplifier and alignment mark in the first mask plate. The width of gap is 50 μm. There is the pattern of center area of the ion focusing groove and alignment marks. Put the first mask plate on the photoresist layer and expose it under the ultraviolet light. Then, postbake the photoresist layer to obtain the crosslink layer. The first layer mold with gaps, wall surface and alignment marks structure is completed after developing.
The second photolithography: spin coat the second photoresist layer with 350 μm thick and prebake the photoresist. Put the second mask onto the photoresist layer. Align the mark of the first photolithography with the one on the second mask plate. Then, expose it under the ultraviolet light. Then, postbake the photoresist layer to obtain the crosslink layer. The second layer mold with the microstructure of the center area of the ion focusing groove gaps, wall surface and alignment marks structure is completed after developing.
The mold of MEMS 2D air amplifier is fabricated by the above said two photolithography steps.
(2) The chips casting: after making the MEMS 2D amplifier mold, casting PDMS to obtain a PDMS amplifier structure. Casting another one in the same way.
(3) The first chips bonding: drill a hole near to the gap in one of the PDMS structure as a gas inlet. Bond two PDMS chips together by the aligning marks to obtain a whole PDMS air amplifier.
(4) The second chips bonding: drill a hole on the glass in the same position of the said whole PDMS air amplifier. Then, bond the glass with the PDMS air amplifier to form the final MEMS 2D air amplifier focusing device.
The said angle between gap and the axis of amplifier and the width of gap is adjustable by designing the first mask plate when fabricating the MEMS 2D air amplifier ion focusing device.
The said height of MEMS 2D amplifier mold is adjustable by spinning the photoresist with the different thickness when fabricating the MEMS 2D air amplifier ion focusing device.
The said PDMS amplifier structure can be formed in one time and bonded with the plate when fabricating the MEMS 2D air amplifier ion focusing device.
The gas enters into the chamber from the gap inlet, and the gas was extruded in the gap and its velocity is increased. The nitrogen gas moves along the right side of wall by the Coanda effect and a pressure drop generated by the high speed nitrogen gas velocity occurs due to the Venturi effect, which induces the airflow around the wall surface. The electrospray ions are focused and desolvated by the induced airflow. Therefore, the transmission efficiency is improved in this way. The present invention has the advantages of simple fabrication process, low cost and small dimension size.
The following attached figures are the detailed description of this invention.
In the figures: 1 inlet, 2 gap, 3 wall, 4 center area of the ion focusing groove, 5 silicon wafer, 6 silicon dioxide, 7 photoresist layer, 8 the first mask plate, 9 crosslink layer, 10 the second mask plate, 11 PDMS, 12 glass substrate.
Referring to the
As shown in
The nitrogen gas enters into the chamber from the inlet, and the nitrogen gas was extruded in the gap and its velocity is increased. The gas moves along the wall by the Coanda effect and a pressure drop generated by the high speed gas velocity occurs due to the Venturi effect, which induces the airflow around the wall surface. The ion plume is focused and speeded up in the center area of the ion focusing groove. Therefore, the transmission efficiency is improved in this way.
As shown in the
The summary of fabrication process flow for the structure of
The final structure of MEMS 2D air amplifier ion focusing device fabricated by the above process flow is shown in
The structure of air amplifier shown in
The above described methods are only the optimum ones of present invention, which cannot be the pattern limitation. All equivalent structures and process flows related to the attached figures in the present invention directly/indirectly applied in the other relevant technical areas are also included within the pattern protective area of the present invention.
Number | Date | Country | Kind |
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2012 1 0073540 | Mar 2012 | CN | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/CN2012/075903 | 5/22/2012 | WO | 00 | 9/16/2014 |
Publishing Document | Publishing Date | Country | Kind |
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WO2013/163834 | 11/7/2013 | WO | A |
Number | Name | Date | Kind |
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6992299 | Lee | Jan 2006 | B2 |
20030026740 | Staats | Feb 2003 | A1 |
Number | Date | Country |
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1621945 | Jun 2005 | CN |
1811421 | Aug 2006 | CN |
2437844 | Nov 2007 | GB |
WO 0041214 | Jul 2000 | WO |
Number | Date | Country | |
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20150060688 A1 | Mar 2015 | US |