Michael Albin

Transient liquid crystal thermometry of microfabricated PCR vessel arrays

Polymerase chain reaction (PCR) using micromachined structures promises improved temperature uniformity and cycling time together with decreased reagent and sample volumes. Thermal design of these structures will benefit from measurements of the temperature distribution in the reacting liquid. We report measurements of temperature uniformity and time constant in a microfabricated 18-vessel array using encapsulated liquid crystals suspended in the liquid. Separate sets of crystals are used to image temporal and spatial temperature variations near the processing thresholds of 55/spl deg/C and 95/spl deg/C with a resolution of 0.1/spl deg/C. While the thermometry technique developed here is particularly useful for characterizing microfabricated PCR systems, it can also aid with the thermal design of a broad variety of microfluidic devices.

Miniature spectrometers for biochemical analysis

Miniature spectrometers were demonstrated by mounting micromachined diffraction gratings onto CCD imaging devices. Two implementations were tested: one for high dispersion and high sensitivity applications, and the other for low-cost consumer applications. The first system showed a dispersion of 1.7 nm/pixel and a resolution of 74.4 for the bandwidth of interest. The free spectral range of these devices was designed to be in the visible range for this particular application. The diffraction efficiency of the system was 63%. The second, low-cost system demonstrated a dispersion and resolution of 2.55 nm/pixel and 69.8 respectively. These specifications are comparable to that of a conventional, low-end commercial spectrometer. Results are shown for their applications in biochemical analysis. Optimization was sought by adding micromachined lenses and creating specialized, computer generated gratings to compress and shape the spectral signal.

The use of capillary electrophoresis in a micropreparative mode: methods and applications.

The ability to collect sufficient quantities of analytes from capillary electrophoresis for subsequent analyses is demonstrated. Fractions collected have been analyzed using the following techniques: capillary electrophoresis, mass spectrometry, and protein sequencing. Fractions can be collected directly into small volumes of buffer or directly onto membrane surfaces. Relevant parameters such as capillary diameter, mass loading, and separation parameters are addressed.

Process Control for Optimal PCR Performance in Glass Microstructures

Miniaturization has the potential to impart cost, performance, size, throughput, and ease-of-use benefits to many fields of analysis. We have demonstrated the ability to perform real-time fluorescence detection of polymerase chain reaction (PCR) products in various fabricated microstructures. Utilizing surface chemical analysis, we have optimized the fabrication process method for glass microstructures for PCR. Chemical “cleanliness” supersedes particle issues for these bioanalytical microdevices, a distinct deviation from integrated circuit development from which the microfabrication processes were derived.

Micro-Genetic Analysis Systems

Viability of key molecular biology processes, PCR and electrophoresis, are experimentally demonstrated in microstructures of various materials. The concurrent development of computer-aided design (CAD) tools to model these processes are intended to aid in improvement of designs and the integration of process elements.

Gene-Based Detection of Microorganisms in Environmental Samples Using PCR

Contaminating microorganisms pose a serious potential risk to the crews well being and water system integrity aboard the International Space Station (ISS). We are developing a gene-based microbial monitor that functions by replicating specific segments of DNA as much as 10(exp 12) x. Thus a single molecule of DNA can be replicated to detectable levels, and the kinetics of that molecules accumulation can be used to determine the original concentration of specific microorganisms in a sample. Referred to as the polymerase chain reaction (PCR), this enzymatic amplification of specific segments of the DNA or RNA from contaminating microbes offers the promise of rapid, sensitive, quantitative detection and identification of bacteria, fungi, viruses, and parasites. We envision a small instrument capable of assaying an ISS water sample for 48 different microbes in a 24 hour period. We will report on both the developments in the chemistry necessary for the PCR assays to detect microbial contaminants in ISS water, and on progress towards the miniaturization and automation of the instrumentation.

Methods Optimization for the Analysis of Peptides Using Capillary Electrophoresis

Publisher Summary This chapter discusses the optimization methods for the analysis of peptides using capillary electrophoresis (CE). CE is a relatively new analytical technique in which separations are performed in narrow inside diameter columns at high field strengths. Separations in narrow, silica capillaries at high field strengths are defining features of the technique. The narrow diameters permit the use of high fields because of the efficient heat dissipation in the narrow columns. The nature of the separation media and the structure of the analytes influence the observed mobility of the analytes under a given set of conditions. The observed mobility is a sum of the electroosmotic mobility (EOF) and the analyte mobility. The EOF is the bulk flow of liquid because of the surface charge on the capillary. The effect of a number of separation parameters on Joule heating, EOF, and analyte mobility are described in the chapter with respect to the optimization of separation conditions. A decrease in capillary diameter will result in a decrease in the current flow as well as an increase in the thermal efficiency of the system.