Microfluidic Component Assembly

Microfluidic component assembly Microfluidic integration Microfluidic systems assembly Microfluidic systems packaging... 

Mechanical joints for assembling microfluidic components and systems often involve insertion of one part into another. The aforementioned cartridges are a simple example, and structures must be included on both the cartridge and inside the instrument to allow smooth insertion. Such structures can include micro-rails to aid such sUding assembly on-chip. Care must be taken in choosing materials for properties such as friction and wear. Friction is deflned as the force of motion or tendency toward such of two surfaces in contact, defined by the equation ... 

Due to the difficult and slow nature of assembling complicated microscale devices and systems in a serial and/or deterministic way, self-assembly has generated a lot of research interest as a possible solution to overcome these problems. Many researchers have demonstrated self-assembly on the microscale. Some notable examples include self-assembly of optical components, self-assembly on non-planar surfaces, and self-assembly of microfluidic devices. One group of researchers in Taiwan has even proposed using a microfluidic system for the self-assembly of microfluidic components. Although self-assembly is utilized by many researchers, further research is needed before self-assembly becomes a commonplace microassembly method of microfluidic systems of increasing complexity. 

A batch fabrication process combining the assembly of two molded parts witii die transfer of a diaphragm from a wafer to one of these parts was developed to fabricate micro-pumps [10]. Then it was shown that a similar process can be applied in the manufacture of microvalve systems [11]. This process allows microfluidic components and microfluidic handling modules to be made from a variety of materials with rather conq>lex geo-metries. SkMWifer orim... 

No smart solution is available to store the gaseous hydrogen used in miniature fuel cell (PEMFC) and hence DMFC is receiving enormous interest due to system simplicity. However, specialised air-breathing DMFC components have to be developed. New materials have to be developed in addition to optimisation of structure and operating conditions to take care of performance decay modes. New membrane/electrode assemblies appropriate for the microscale to be developed exploiting the enhanced heat and mass transfer on the microscale for improved performance, and developing microfluidic components for micro fuel cells. 

Making the size of each optical component for LIF as small as possible and assembling them onto microfluidic systems is a straightforward way to develop a portable analyzer as described above. Another idea to minimize the instmments is to design and fabricate all optics directly on-chip, which means that the optics such as light source [58-60], lens [61, 62], and detector [63] are part of the microchip rather than minimizing them and interfacing them with microchip. This self-contained optical microfluidic, also called optofluidic, is reviewed in the Sect. 3 of this article. 

Sorting can be seen as a preliminary assembly step. Particle sorting has been known as a common application for microfluidic devices and could be integrated into a microfluidic assembly system. While most sorting methods utilize spherical components, railed microfluidic chaimels have been created to sort and control orientation of non-geometric components [6]. Furthermore, concept of space confinement within a microfluidic channel has been applied to the assembly of microscale components into structures that resemble polymer chains [7]. 

Microfluidk Assembly, Fig.1 Modular microfluidic board approach (a) illustration of example board technology with electronic and fluidic routing between surface-mounted components and coupling to off-chip devices (b) photograph of example microfluidic board in silicon with live mounted pressure sensors, embedded microchannels, surface electronic routing, and couplers to capillary tubing [2]... 

A major issue with many microfluidic interconnect technologies is the coupling of the fluidic circuits to the macroscopic world. Such couplers allow fluid to be pumped on-chip, and waste to be removed off-chip in a controlled manner. Couplers can be integrated into the fabrication process or assembled to the device as a separate component. 

What has inspired initial research in microfluidics is similarly driving the research into optofluidics today. The goal is to make smaller features going from micro- to nanoscales in order to fill the gap between top-down and the bottom-up fabrication techniques [7]. Because most devices consist of multiple planar layers, there is motivation to develop 3-D fabrication or assembly methods for both optical and electrical components. The ultimate goal is an easy and simple technique which works well with a variety of materials and on different scales. The most successful devices up to date rely on fundamental principles of both optics and fluidics in order to avoid as many of components as possible, leaving those devices only with essentials to carry out their fimctions. 

---