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Introduction

 

Abstract

            The purpose of this project is to design an inexpensive electrical detection sensor, capable of measuring various concentration levels in a microfluidic channel. During the first 3 weeks, a microfluidic chip will be designed to measure different concentration levels of proteins coated with sodium dodecyl sulfate (SDS). During the last six weeks the microfluidic chip will be fabricated, tested, and modified accordingly.
 

Introduction

        Microfluidics aims at developing miniaturized devices which can sense, separate, and control small volumes of fluids [1]. Due to the demand for small scale instrumentation, there is a great need for compatible modes of sensors and detectors. Electric detectors are capable of providing effective measurements in microfluidic systems through electrochemical methods of amperometry, potentiometry and conductometry. One electric detector capable of separating various proteins in a microfluidic channel is the conductivity detector for microchip capillary electrophoresis. However, despite the electric detectors’ effectiveness it is very high in cost. Our goal is to develop and fabricate an inexpensive electric detector which can measure the concentration of proteins coated with SDS.  After the analysis of the experimental data, we will examine the flaws of the design and improve the performance of the detector.

 

Background

Microfluidics is the science of designing, manufacturing, and formulating devices and processes that deal with volumes of fluid on the order of nanoliters. It first originated at Stanford University 20 years ago, with the use of a chromatograph. Soon after, IBM adopted the idea and incorporated it in the manufacturing of inkjet printers. In the years that followed, microfluidic devices emerged in such fields as biomedical research, environmental monitoring, and forensic investigations [3]. Furthermore, microfluidic devices were used to obtain a wide variety of measurements including pH, molecular diffusion coefficients, fluid viscosities, and reaction kinetics. Microfluidic devices provide portability, fast response, low cost, and low power consumption [4]. In addition, because of the small dimensions of channels within the chip, no turbulent mixing occurs. The limited mixing allows detectors such as the electric sensor to function in a precise manner.

Microfluidics is important in biological systems because they provide small scale separations and detection modes used in clinical diagnostics and biological assays. The electric sensor design which our group is developing will provide a low cost means of measuring concentrations of proteins coated with SDS. The importance of this design stems from the need to find the size of certain proteins while limiting reagent consumption.

            With the completion of the human genome project and the identification of approximately 30,000 human genes, emphasis is shifting to the various proteins that are expressed by our genes [5]. Proteins are vital to life in the cell because they provide structure, produce energy and allow communication, movement and reproduction. Proteins also play a key role in diseases and can be used as targets for the design of new drugs. This importance of proteins has given rise to many microfluidic sensor designs capable of measuring the size of various proteins.

            The traditional method of protein analysis involves two main systems of detection: polyacrylamide gel electrophoresis and mass spectroscopy. Both analysis systems are very effective however the cost and size of each system is both expensive and bulky. Although microfluidic detection modes used in capillary electrophoresis provide small scale instrumentation, the cost of this sensor is still very high. Our objective is to design, fabricate and conduct experiments on a microfluidic chip capable of measuring various concentrations of protein coated with SDS. 

 

Conclusion

        The purpose of this project is to develop an inexpensive and efficient microfluidic chip capable of measuring various concentrations of protein coated with SDS. As the future leans more heavily towards small scale systems of analysis, microfluidic chips become increasingly important. Development of an electrical microfluidic sensor can provide for these small scale systems through cheap, portable, and easily controlled technology.

 

References

1.   Frazier B, Ahn C. Microfluidic Devices and Systems, Santa Clara,   
      California:   SPIE; 1998.
 
      2.  Frazier B, Ahn C. Microfluidic Devices and Systems II, Santa Clara,       
           California:     SPIE; 1999.
 
      3. Mastrangelo C, Becker H. Microfluidic Devices and Systems III Santa       
          Clara, California:   SPIE; 1998.
 
      4.  Yager P. Microfluidic Turorial- a Highly Biased Primer. Yager Group         
           Website. 2005. Available at:
      <http://faculty.washington.edu/yagerp/microfluidicstutorial/tutorialhome.htm>
 
      5. Kamholz A. Quantitative Analysis of Molecular Interaction in a Microfluidic             
          Channel. 1999; 71, 5340-5347. Available at:
      <http://web.mit.edu/10.491/Tsensor.pdf>