Microfluidic system automatic

Microfluidics is the key to NLC and NCE, the miniaturized microfluidic system that can automatically carry out all the necessary functions to transform chemical information into electronic information. The first p.-TAS device was developed by Terry et al. [23] for gas chromatography, which did not gain popularity at that time, probably due to poorly developed microfluidic devices. In 1990, Manz et al. [24] introduced the concept of p.-TAS. Nowadays, fx-TAS is a popular development in various disciplines and has been reviewed by Manz and coworkers [25-28]. 

In this chapter, we first discuss flow injection analysis (ITA), a recent and important type of continuous flow method. We next consider microfluidic systems, which are miniaturized types of continuous flow units. We then describe several types of discrete automatic systems, several of which are based on laboratory robotics. 

Utilizing the interplay of interface generated forces with hydrodynamic forces and geometrical constrictions even complex tasks like closed-loop control cycles can be implemented in microfluidic systems. These opportunities have been applied for the development of a smart operation unit for droplet merging with automatically outbalancing of timing errors for the droplets arrival. 

We discuss in this chapter analyzers that are highly automated, such as flow injection and discrete analyzers. In addition, laboratory robotic systems that are becoming more and more commonplace for sample handling and preparation are also described. The latest advances in automation involve the development of microfluidic systems, which are sometimes called lab-on-a-chip or micro total analysis systems. These recent developments are also described here. It is important to note that the same principles of automatic analysis discussed here also apply to process control systems, which analyze the current state of a process and then u.se feedback to alter experimental variables in such a way that the current state and the desired state are nearly identical. 

Huang, C.-J., Chen, Y.-H., Wang, C.-H., Chou,T.-C. and Lee, G.-B. (2007) Integrated microfluidic systems for automatic glucose sensing and insulin injection . Sensors and Actuators B Chemical, 122,461-468. 

As in the SLM systems, FS- and HF-MMLLE configurations can be run automatically in flowing modes and operated off-line or connected on-line to analytical instruments. Recently, a microfluidic chip-based FS-MMLLE system was reported.83 In addition, miniaturized, nonautomated, nonflowing, off-line MMLLE systems are usually used with HF membranes. The emphasis in this section will be placed on these latter modes of MMLLE operation. 

Recently, a new approach was proposed to overcome these problems, based on a microfluidic chip device (Agilent, 2007) (Fig. 1.11). This finding includes the enrichment column, the separation column, and the nanospray emitter. By use of a robotic system, the chip is automatically positioned in front of the entrance orifice of the mass spectrometer. 

Development of microfluidics-based systems wifii small sample volumes and reduction of extensive sample cleanup requirements prior to analysis Need for well defined biochemical markers of quality for a variety of foods Low cost sensor-based analytical systems with automatic monitoring and reporting, e.g., via wireless-based systems Regulatory Agency approval for use of sensor technologies... 

Automatic macromodel extraction that takes advantage of high-fidelity device simulations (e.g., FEM, FVM, and BEM) to extract RLC values in irregular microchannel geometries has also been reported. Turowski et al. [11] approximate the microfluidic Tesla valve as an/ L circuit (serial connection of a resistor R and an inductor L in Fig. 5) and performed both steady and transient analysis to extract its fluidic resistance and inductance. The macromodels are then stitched together for an overall system simulation on the pumping performance. 

The analytical technique proposed by Hungerford et al. (1990) is based on microfluidic manipulation of samples and reagents, whereby samples are injected into a carrier/ reagent solution that transports the sample to a detector. The first stage of this FIA system combines an HPLC composed of an automatic injector, a pump, and an oven to act as a thermostat for the reaction of the amines with the OPA. One channel of the HPLC was used to propel the HCl stream, and the two reactor pumps were used to push the OPA and phosphoric acid reagent streams. The fluorescence detector was then connected. This was operated at excitation and emission wavelengths of 365 and 450 nm, respectively (Figure 35.2). 

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