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Robust and economical multi-sample, multi-wavelength UV/vis absorption and fluorescence detector for biological and chemical contamination
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1. R. Gomes, R. Liteplo, and M. E. Meek, Ethylene glycol: human health aspects (World Health Organization, 2002).
2. V. Velusamy, K. Arshak, O. Korostynska, K. Oliwa, and C. Adley, Biotech. Adv. 28, 232 (2010).
3. P. Yager, G. J. Domingo, and J. Gerdes, Annu. Rev. Biomed. Eng. 10, 107 (2008).
4. United States Food and Drug Administration, Guidance for Industry: Testing of Glycerin for Diethylene Glycol (2010).
5. European Commission Scientific Committee on Consumer Products, Opinion on Diethylene Glycol (2008).
6. United States House of Representatives Subcommittee on Science and Technology, FDA: Science and Mission at Risk (2007).
7. EG poisonings episodically kill hundreds in third-world countries, even today. The realization that there is no existing low-cost method for detecting such poisons motivated the research that led to the device and chemistry methods presented here.
8. J. H. Eckfeldt and R. T. Light, Clin. Chem. 26, 1278 (1980).
9. S. Schultz et al., Morb. Mortal. Wkly. Rep. 36, 611 (1987).
View: Figures


Image of FIG. 1.

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FIG. 1.

Device schematic. UV light emitted by an LED (L1) passes through an excitation filter (F1), the sample, and another filter (F2) before its absorption is detected (D1). Optical feedback using an additional sensor (D4) and op-amp (A1) maintains a constant light output from L1, whose level is set by the microcontroller (M1) via a voltage generated by a D/A converter (C1). Light from a similarly stabilized green LED (L2, D5, A2) is filtered (F3) before passing through the sample; green light is filtered and detected for green absorption (F4, D2) and red fluorescence (F5, D3). Voltage outputs from the detectors (D1, D2, D3) are digitized by an A/D converter (C2) and sent to the microcontroller (M1), which formats and transmits the data via USB (F1) to a computer, smart mobile-phone or tablet.

Image of FIG. 2.

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FIG. 2.

(A) Circuit diagram showing specific electrical components of our detector, with microcontroller (M1), D/A converter (C1), A/D converter (C2) and USB Interface (F1) components labeled as in Fig. 1 . (B) Photograph of the detector (black, upper left) and circuit boards, with major components labeled with red letter corresponding to labels in (A) and in Fig. 1 .

Image of FIG. 3.

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FIG. 3.

(A) 3D model of our as-built device. One chamber has the black plastic enclosure removed, to illustrate the positions of LEDs, filters and sample-holding test tube. (B) View of the bottom of the plastic enclosure, showing openings for two LEDs (L1 and L2 in Fig. 1 ) and 3 light-to-voltage detectors (D1, D2 and D3 on Fig. 1 ). (C) Close-up of the opening for one light-to-voltage detector, showing slit for thin filter plastic.

Image of FIG. 4.

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FIG. 4.

Time evolution of output voltage () from the UV detectors, digitized as 16-bit integer, shown on a log-log plot with symbols for different EG concentrations in water. The data fall onto a straight line for each sample, demonstrating power-law scaling. The magnitude of the slope of each line γ( ) varies monotonically with .

Image of FIG. 5.

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FIG. 5.

γ( ) varies monotonically with , shown with blue circles for pure EG in water, and green squares for antifreeze, which follow the same trend, shown in black as a guide to the eye. Data point represent averages over several runs, with error bars corresponding to the standard deviation of the measurements. FDA safety limit = 10−3 is indicated with a grey vertical line.

Image of FIG. 6.

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FIG. 6.

Comparison of the detection of the same glucose oxidase-based reaction, which generates a fluorescent product, in our detector and in a commercial fluorscence plate reader. Data point represent averages over several runs, with error bars corresponding to the standard deviation of the measurements.


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We present a portable multi-channel, multi-sample UV/vis absorption and fluorescence detection device, which has no moving parts, can operate wirelessly and on batteries, interfaces with smart mobile phones or tablets, and has the sensitivity of commercial instruments costing an order of magnitude more. We use UV absorption to measure the concentration of ethylene glycol in water solutions at all levels above those deemed unsafe by the United States Food and Drug Administration; in addition we use fluorescence to measure the concentration of -glucose. Both wavelengths can be used concurrently to increase measurement robustness and increase detection sensitivity. Our small robust economical device can be deployed in the absence of laboratory infrastructure, and therefore may find applications immediately following natural disasters, and in more general deployment for much broader-based testing of food, agricultural and household products to prevent outbreaks of poisoning and disease.


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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Robust and economical multi-sample, multi-wavelength UV/vis absorption and fluorescence detector for biological and chemical contamination