Development of microfluidic LED sensor platform
© Kim et al.; licensee Springer. 2015
Received: 30 December 2014
Accepted: 18 January 2015
Published: 17 June 2015
We developed the microfluidic light emitting diode (LED) sensor for methanol detection. The linear gradient-generating microfluidic device consists of two inlet and four outlet microchannels. The concentration gradients of methanol were stably generated in the microfluidic platform in a temporal and spatial manner. The methanol harvested from microfluidic platforms was analyzed by measuring electrical conductivity, showing that currents were decreased with the methanol content. The methanol in the microfluidic device was also observed by LED sensor. Therefore, this microfluidic LED device could be a powerful platform for methanol sensor applications.
Methanol, the simplest alcohol and organic solvent, has widely been used for fuel cell and biochemical applications [1-3]. The direct methanol fuel cell is of great benefit for portable electronic devices, because it enables increase of power density and decrease of operating temperature [4-6]. The physical and chemical properties of methanol are also similar to gasoline, showing that methanol is a good candidate as a fuel cell in automotive engines [7-9]. Despite many methanol-based industrial applications, the major problem is still remained, such as methanol toxicity, which can cause severe disease of metabolic acidosis, nerve disorder, olfactory mucosa, and blindness . Although small amount of methanol is inhaled, methanol becomes toxic formic acid via formaldehyde as previously described . In general, the volatile organic compound (e.g., methanol), which can be conventionally detected by gas chromatography technique, has low boiling point and high reactive property. Thus, the development of the platform technology to detect the methanol at room temperature has become imperative .
Microfluidic devices have previously been developed to generate concentration gradients and detect biomolecules [13-15]. Recently, an integrated microfluidic device has been developed to quantify methanol concentrations . The methanol and methanol oxidase infused into the poly(methyl methacrylate) (PMMA)-based microfluidic device. The injected solutions were heated at 45°C to generate formaldehyde and methanol concentrations were subsequently observed by ultraviolet (UV) spectrophotometer. The accuracy of microfluidic device-based methanol detection was approximately 93% compared to gas chromatography method. Integrated microfluidic device has been developed to detect methanol concentrations . The system consisted of light emitting diode (LED) photometer, PMMA-based microfluidic device, photodiode, voltmeter, and temperature controller. The samples were loaded and were subsequently mixed by a vortex stirrer in the microfluidic device. The colorimetric reaction of the mixtures was performed by thermoelectric cooler and micro-hotplate systems. LED photometer system detected methanol concentrations in the microfluidic device. Furthermore, microfluidic device has been developed for direct methanol fuel cell applications . For the fuel cell, methanol and oxygen was employed as an anode and cathode, respectively. The microfluidic device containing anode flow fields enabled the generation of liquid–gas meniscus. It showed that the interfacial mass-transfer resistance was largely generated by evaporation of the small meniscus, resulting in inhibition of methanol delivery to anode catalyst layers. The flow field enabled the formation of passive direct methanol fuel cells containing higher methanol concentrations. However, previous approaches have used complex integrated microfluidic devices to detect methanol gas at high temperature. To overcome these limitations, we developed the linear gradient-generating microfluidic device to monitor and quantify the methanol at room temperature using programmed microcontroller, LED sensor, and electrical conductivity analysis. Therefore, this microfluidic LED device could be a powerful tool for methanol sensor applications.
2.1 Fabrication of the microfluidic device to generate methanol concentration gradients
2.2 Experimental set-up
The microfluidic device containing two inlets and four outlets allowed streams of solutions to generate laminar flow in parallel without any convective mixing. To generate concentration gradients in the microfluidic device, the methanol and buffer solutions were injected with a uniform flow rate (66 μl/min) using a syringe pump (Harvard Apparatus, USA). The methanol was analyzed by measuring current–voltage (I-V) curve using source meter and Labview programming.
2.3 Computational simulation
C is the concentration, u is the velocity vector calculated by the Navier–Stokes equations (1) and (2). D is the diffusion coefficient (2.19 × 10−9) at the condition of 0.1 MPa and 298.5 K . The number of elements of mesh used in this simulation was approximately 116,632. Consequently, the optimal flow rate (66 μl/min) generated by a syringe pump was calculated.
2.4 Electrical circuit diagram for LED sensor
3 Results and discussion
Analog/digital (A/D) conversion voltage used in a microcontroller
A/D voltage (V)
A/D voltage (V)
We developed the microfluidic LED sensor for methanol detection. The linear gradients of methanol were generated in the microfluidic device. The methanol harvested from the microfluidic device was analyzed by electrical conductivity and LED sensor. We demonstrated that the electrical conductivity was decreased with increasing the methanol and each percentage of the methanol was also observed by LED sensor. Therefore, this microfluidic LED device for methanol detection could be a powerful tool for methanol sensor applications.
This research was supported by BioNano Health-Guard Research Center funded by the Ministry of Science, ICT & Future Planning (MSIP) of Korea as Global Frontier Project (Grant number H-GUARD_2014M3A6B2060503), Republic of Korea. This work was also supported by Leading Foreign Research Institute Recruitment Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (MSIP) (2013K1A4A3055268) and the Sogang University Research Grant of 2014 (Grant Number SRF-201414001).
- H Guo, X Chen, Y Yao, G Du, H Li, Detection of ethanol and methanol vapors using polymer-coated piezoresistive Si bridge. Sensor Actuat. B-Chem. 155, 519–523 (2011)View ArticleGoogle Scholar
- Q Liu, JR Kirchhoff, Amperometric detection of methanol with a methanol dehydrogenase modified electrode sensor. J. Electroanal. Chem. 601, 125–131 (2007)View ArticleGoogle Scholar
- LO Peres, RWC Li, EY Yamauchi, R Lippi, J Gruber, Conductive polymer gas sensor for quantitative detection of methanol in Brazilian sugar-cane spirit. Food Chem. 130, 1105–1107 (2012)View ArticleGoogle Scholar
- RX Wang, JJ Fan, YJ Fan, JP Zhong, L Wang, SG Sun, XC Shen, Platinum nanoparticles on porphyrin functionalized graphene nanosheets as a superior catalyst for methanol electrooxidation. Nanoscale 6, 14999–15007 (2014)View ArticleGoogle Scholar
- YL Hsin, KC Hwang, CT Yeh, Poly(vinylpyrrolidone)-modified graphite carbon nanofibers as promising supports for PtRu catalysts in direct methanol fuel cells. J. Am. Chem. Soc. 129, 9999–10010 (2007)View ArticleGoogle Scholar
- Z-B Wang, C-R Zhao, P-F Shi, Y-S Yang, Z-B Yu, W-K Wang, G-P Yin, Effect of a carbon support containing large mesopores on the performance of a Pt− Ru− Ni/C catalyst for direct methanol fuel cells. J. Phys. Chem. C 114, 672–677 (2009)View ArticleGoogle Scholar
- D-S Park, M-S Won, RN Goyal, Y-B Shim, The electrochemical sensor for methanol detection using silicon epoxy coated platinum nanoparticles. Sensor Actuat. B-Chem 174, 45–50 (2012)View ArticleGoogle Scholar
- J Li, L Dai, A hard modeling approach to determine methanol concentration in methanol gasoline by Raman spectroscopy. Sensor Actuator B. Chem. 173, 385–390 (2012)View ArticleGoogle Scholar
- Q Xu, Q Ye, H Cai, R Qu, Determination of methanol ratio in methanol-doped biogasoline by a fiber Raman sensing system. Sensor Actuator B. Chem. 146, 75–78 (2010)View ArticleGoogle Scholar
- D Jacobsen, KE McMartin, Antidotes for methanol and ethylene glycol poisoning. J. Toxicol. Clin. Toxicol. 35, 127–143 (1997)View ArticleGoogle Scholar
- J Brent, K McMartin, S Phillips, C Aaron, K Kulig, Fomepizole for the treatment of methanol poisoning. N. Engl. J. Med. 344, 424–429 (2001)View ArticleGoogle Scholar
- MB Gholivand, A Azadbakht, A nano-structured Ni(II)-chelidamic acid modified gold nanoparticle self-assembled electrode for electrocatalytic oxidation and determination of methanol. Mat. Sci. Eng. C. Mater. 32, 1955–1962 (2012)View ArticleGoogle Scholar
- JR Anderson, DT Chiu, H Wu, OJ Schueller, GM Whitesides, Fabrication of microfluidic systems in poly (dimethylsiloxane). Electrophoresis 21, 27–40 (2000)View ArticleGoogle Scholar
- Y Zhou, Q Lin, Microfluidic flow-free generation of chemical concentration gradients. Sensor Actuator B. Chem. 190, 334–341 (2014)View ArticleGoogle Scholar
- BG Chung, K-H Lee, A Khademhosseini, S-H Lee, Microfluidic fabrication of microengineered hydrogels and their application in tissue engineering. Lab Chip 12, 45–59 (2012)View ArticleGoogle Scholar
- Y-N Wang, R-J Yang, W-J Ju, M-C Wu, L-M Fu, Convenient quantification of methanol concentration detection utilizing an integrated microfluidic chip. Biomicrofluidics 6, 034111 (2012)View ArticleGoogle Scholar
- L-M Fu, W-J Ju, C-C Liu, R-J Yang, Y-N Wang, Integrated microfluidic array chip and LED photometer system for sulfur dioxide and methanol concentration detection. Chem. Eng. J. 243, 421–427 (2014)View ArticleGoogle Scholar
- QX Wu, TS Zhao, R Chen, WW Yang, A microfluidic-structured flow field for passive direct methanol fuel cells operating with highly concentrated fuels. J. Micromech. Microeng. 20, 045014 (2010)View ArticleGoogle Scholar
- ZJ Derlacki, AJ Easteal, AVJ Edge, LA Woolf, Z Roksandic, Diffusion coefficients of methanol and water and the mutual diffusion coefficient in methanol–water solutions at 278 and 298K. J. Phys. Chem. 89, 5318–5322 (1985)View ArticleGoogle Scholar
- BG Chung, F Lin, NL Jeon, A microfluidic multi-injector for gradient generation. Lab Chip 6, 764–768 (2006)View ArticleGoogle Scholar
- BG Chung, J Choo, Microfluidic gradient platforms for controlling cellular behavior. Electrophoresis 31, 3014–3027 (2010)View ArticleGoogle Scholar
- D Salvi, D Boldor, GM Aita, CM Sabliov, COMSOL Multiphysics model for continuous flow microwave heating of liquids. J. Food Eng. 104, 422–429 (2011)View ArticleGoogle Scholar
- K Higashikawa, Y Honda, M Inoue, T Kiss, N Chikumoto, N Sakai, T Izumi, H Okamoto, Investigation of three-dimensional current distribution at silver diffusion joint of RE-123 coated conductors based on magnetic microscopy combined with finite element method. IEEE Trans. Appl. Supercond. 21, 3403–3407 (2011)View ArticleGoogle Scholar
- S Ohshima, K Umezu, K Hattori, H Yamada, A Saito, T Takayama, A Kamitani, H Takano, T Suzuki, M Yokoo, S Ikuno, Detection of critical current distribution of YBCO-coated conductors using permanent magnet method. IEEE Trans. Appl. Supercond. 21, 3385–3388 (2011)View ArticleGoogle Scholar
- NG Patel, PD Patel, VS Vaishnav, Indium tin oxide (ITO) thin film gas sensor for detection of methanol at room temperature. Sensor Actuator B. Chem. 96, 180–189 (2003)View ArticleGoogle Scholar
- Y Long, T Wang, L Liu, G Liu, G Zhang, Ion specificity at a low salt concentration in water–methanol mixtures exemplified by a growth of polyelectrolyte multilayer. Langmuir 29, 3645–3653 (2013)View ArticleGoogle Scholar
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