Socket2_English
Last update: 2003/12/12
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Socket2_English Last update: 2003/12/12 |
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Socket with built-in valves for the interconnection of microfluidic chips to macro constituentsZhen Yanga, b and Ryutaro Maeda a Institute of Mechanical Systems Engineering, AIST, Namiki 1-2, Tsukuba 305-8564, Japan b NEDO, Higashi-Ikebukuro, Tokyo 170-6028, Japan Available online 27 August 2003. AbstractThis paper reports a prototype for a standard connector between a microfluidic chip and the macro world. This prototype demonstrate a fully functioning socket for a microchip to access the outside world by means of fluids, data signals and energy supply. It supports up to 10 channels for the input and output of liquids or gases, as well as compressed air or vacuum lines for pneumatic power lines. The socket has built-in valves for each flow channel. It also contains 28 pins for the connection of electrical signals and power. Built-in valves make it possible to control the flow in each channel independently. A chip (11.0×11.0×0.9 mm) can be mounted into or dismounted from the socket with one touch. The fluidic connectors of the socket are designed to contact vertically on the top of chip. And the electrical connectors (the spring array) of that physically support the chip and contact lead pads at the bottom of chip. No adhesives or solders are used at any contact points. The pressure limit for the connection of working fluids was 0.2 MPa and the current limit for the electrical connections was 1 A. This socket supports both serial and parallel processing applications. It exhibits great potential for developing microfluidic systems efficiently. Subject-index terms: Chip technology; Instrumentation;
Microfluidics Article Outline
1. IntroductionWith the development of micro-electro-mechanical systems (MEMs), microfluidic applications have increased in importance since the 1990s. A great deal of effort has been devoted to integrate the functions of sample pretreatment, separation and detection onto one chip. Methods for creating networks of microchannels are well established in silicon, glass and polymeric substrates, using etching or molding processes. PZT-actuated micropumps and micromixers have achieved excellent performance and various microsensors have also been reported. These have been well reviewed by Reyes et al. [1] and Auroux et al. [2]. As commercialization of MEMs and microsystems gains momentum, product packaging has also gained increasing attention within the industrial and research communities. Packaging of a MEMs device generally takes up 50–90% of its cost, with 80% the norm [3]. Not surprisingly, packaging has been a major stumbling block in capitalizing the full market potential of microengineering products. Generally, there are four steps: design, fabrication, packaging and testing, for proof-of-concept prototype development. In our experiences of microfluidic device developments, packaging is the lowest efficient step. We have presented our first packaging solution [4]. It concerns process visibility greatly. The top of chip is totally opened to microscopic observation. However, the dicing dusts in flow channels are difficult to avoid. Because dicing process is for not only separating each chip but also the finally forming of fluidic connecting ports on the sidewall of the chip. For ordinary microchannels or micromixers, dicing dusts make tiny effects on their performances. Dicing dusts do not clog micro flow channels. For microvalve application, however, it needs extremely particle-free environment to avoid leakage. Therefore, the flat fluidic connection socket is not suitable for microfluidic devices with built-in microvalves. In this paper, another type of interconnection socket was reported. This
socket was designed for the microfluidic chip that needed vertical fluidic
connections. With its built-in valves, this socket supplies a way to control the
flow in each channel independently. The socket is shown in Fig. 1.
Fig. 1. Photo of the socket. The silicone tubes for fluidic connection are in dual-in-line structure with a pitch of 2.2 mm. There are 10 channels available for I/O of working fluids. The screw over each silicone tube works as a valve. This socket is for the fluidic chip in the size of 11.0×11.0×0.9 mm.
Fig. 2. Schematic drawings of the cross-section of the socket mounted with a fluidic chip (not scaled). The upper part shows the structure of the socket. The silicone tubes are extended a little out of the acrylic plate. In the screw valve, a ball is inserted to avoid the damage directly from screw to silicone tube. The chip for testing is aligned easily following the guides and is supported by the lead spring array. The bottom part shows the state for testing. The extended silicone tubes are deformed and serve as O-rings to seal the flow channel ports on fluidic chip. The spring array for electrical connection is contacted firmly to the lead pads formed on the backside of the chip. Both working fluidic and electrical connections are adhesive/solder-free. These structures made it efficiently to mount or dismount a microfluidic device.
Fig. 3. Photo of a microfluidic valve mounted in a socket. The socket has only eight fluidic channels and 18 springs for electrical connections. The chip size is 6.6×6.6×0.9 mm. The top glass part of the microvalve has through holes with a pitch of 2.2 mm.
Fig. 4. Photo of the exchangeable module for fluidic connection in the socket. (Left) The fluidic connection module can be various in thickness or pitch to fit for the chip with different fluidic designs. (Middle) The socket frame. The grooves are the guides for silicone tubes and the hole under each groove is for the screw valve. (Right) The cover for the acrylic module.
References1. D.R. Reyes, D. Iossifidis, P.A. Auroux and A. Manz. Anal. Chem. 74 (2002), p. 2623. For a softcopy of the paper, Download here.
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