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Detection of cocaine on the level of a few ng/ml by the use of lab-on-a-paper test co-working with OLED light source as exciatation light source and CCD-based detection unit is described in this paper. The new method enables not only yes or now answer of drug presence in a tested sample but also concentration of the drug in the sample. Presented here results opens a new way toward portable instrumentation for point-of-care detection of cocaine (and in the future other drugs) in sweat of for example professional drivers. This device will be a drug-tester similar to widely now used alcohol testers

Abstract. Microfluidic devices called lab-on-a-chips utilize two kinds of characterization of a biosample, which are based on spectrofluorimetric and spectrophotometric methodologies. Lab-on-a-chips are equipped with an optical instrumentation and a software system that allow detecting of the optical signals and their processing into spectral characteristics.In the paper, technology of lab-on-a-chip (cytometer microdevice) and miniature silicon-glass field-emission light source (FELS) is described. Electrons emitted from a silicon cathode covered with carbon nanotubes excite light emission from nanocrystalline rare earth doped yttrium oxide phosphor (anode). The emitted light can be precisely tailored to the main absorption line of a fluorescent marker. The presented system has been successfully used for testing of the cow embryos as well as fluorescent-marked porcine oocytes.

New micro-cytometric chip for qualitative, parametrical measurement of living oocytes/embryos of cows and pigs is proposed. The idea of measurement (Figure ) is based on positioning of oocyte/embryo inside a micromachined glass-silicon or glass-PDMS chip with fluidic channel and set of micro-optical devices allowing spectrophotometric (absorption/transmission VIS/NIR spectra) and/or fluorimetric (fixed wavelength) measurements. Our preliminary work showed that cow embryos at different stage of maturity might be characterized by characteristic points of absorption spectra shifted toward longer wavelengths (Figure 2a). The another qualification factor might be a time-dependent decreasing of fluorescence intensity of dye labeled embryo. "Better" oocytes may tend to do not flourish whereas apoptic or necrotic oocytes marked by fluorescent dye are going to flourish at characteristic emission lines (Figure 2b). In this work for the first time, we report micro-cytometer equipped with miniature vacuum field emission light source (FELS) for fluorimetric measurements and able to carry on transmission/absorption measurements in VIS/NIR spectra. FELS sources utilizes cold electron field emission phenomena from carbon nanotubes (Figure 3). They are working on wavelengths adjusted to fluorescent markers used in biochemical analysis (Figure 4).Micro-fluidic channels and via-hole for backside illumination of embryos as well as V-grooves for optical glass fibers positioning were deeply micro-machined in (00)-oriented silicon substrate. Front side of the silicon chip was anodically bonded with a borosilicate glass cover ( Figure 5). Back side of the microchip was bonded to another glass sheet covering the field emission cathode. Glass fibers were placed inside the microchip along special V-grooves and fixed with use of the UV-cured hard epoxy-glue.View of the fabricated silicon-glass micro-cytometer with a back lighted micro-channel is shown in the figure 5b. Actual stage of the work shows that luminescent spectra of fabricated light sources might be well tailored to several fluorescent markers including: Fluorescein, Syto Orange 83 and Syto Red 7.We believe that changes in the oocyte spectra obtained for absorption measurements for VIS illumination may be also observed for measurements with fabricated field emission light sources.In the full paper, technology and results on characterization of animal oocytes, embryos and other living cells will be shown in details.We hope that integration of the micro-fluidic chip for cell micro-cytometry and field emission light sources will simplify the construction of chips and also extends fields of their applications. Acknowledgement