Chemical sensing using an integrated microfluidic system based on the Berthelot reaction

Daridon, Antoine; Sequeira, Margaret; Pennarun-Thomas, GaëIle; Dirac, H.; Krog, J.P.; Gravesen, Peter; Lichtenberg, Jan; Diamond, Dermot; Verpoorte, Elisabeth; Rooij, NF de

doi:10.1016/s0925-4005(01)00573-1

Cited by 80 publications

(54 citation statements)

References 26 publications

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“…In one instance the microfluidic chip was composed of three stacked layers of Pyrex and the optical cuvette was etched by SAE (optical path-length 585 µm, diameter 200 µm). In the second instance, considered in a previous study [6], a silicon wafer was sandwiched between two Pyrex wafers, and the optical cuvette was etched in the silicon layer by DRIE (optical path-length 400 µm, diameter 200 µm). In these experiments, the ammonium standards and reagents were premixed off-chip and the mixture was added into the chip after completion of the reaction.…”

Section: Resultsmentioning

confidence: 99%

“…Step 12: Because the chemical reaction used in these microfluidic chips is slow [5], an indium tin oxide layer is sputtered on top of the chip and used as a resistive heater to increase the reaction rate [6,7]. A stable electrical contact is ensured by evaporation of 200-nm-thick gold strip electrodes over a 10-to 20-nm-thick chromium adhesion layer.…”

Section: Microfluidic Chip Fabricationmentioning

confidence: 99%

“…The integration of the Berthelot reaction for determination of ammonium into a microfluidic system for use in a water-monitoring application has already been described [6,7]. The first generation of devices, consisting of a silicon chip with dry-etched channels sandwiched between two Pyrex chips, proved the feasibility of the microfluidic approach [8].…”

Section: Introductionmentioning

confidence: 99%

“…Streamlines are straight and well defined, so mixing of adjacent sample and reagent streams depends exclusively on radial diffusion perpendicular to the direction of flow. Despite the relative slowness of this molecular transport process, it was found that the use of narrow, deep channels (30 µm wide and 200 µm deep) to minimize the distances species needed to travel enabled efficient mixing by diffusion [6]. Complete mixing of two reagent streams flowing side by side could be accomplished in less than 0.5 s. The issue of sample-zone dispersion was also considered in these first devices, because more peaks can be distinguished per unit time (or more samples analyzed) if sample zone dispersion can be minimized.…”

Section: Introductionmentioning

confidence: 99%

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Multi-layer microfluidic glass chips for microanalytical applications

Daridon

Fascio

Lichtenberg

et al. 2001

Fresenius J Anal Chem

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A new, versatile architecture is presented for microfluidic devices made entirely from glass, for use with reagents which would prove highly corrosive for silicon. Chips consist of three layers of glass wafers bonded together by fusion bonding. On the inside wafer faces a network of microfluidic channels is created by photolithography and wet chemical etching. Low dead-volume fluidic connections between the layers are fabricated by spark-assisted etching (SAE), a computer numerical controlled (CNC)-like machining technique new to microfluidic system fabrication. This method is also used to form a vertical, long path-length, optical cuvette through the middle wafer for optical absorbance detection of low-concentration compounds. Advantages of this technique compared with other, more standard, methods are discussed.When the new glass-based device for flow-injection analysis of ammonia was compared with our first-generation chips based on silicon micromachining, concentration sensitivity was higher, because of the longer pathlength of the optical cuvette. The dependence of dispersion on velocity profile and on channel cross-sectional geometry is discussed. The rapid implementation of the devices for an organic synthesis reaction, the Wittig reaction, is also briefly described.

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Section: Resultsmentioning

confidence: 99%

Section: Microfluidic Chip Fabricationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Multi-layer microfluidic glass chips for microanalytical applications

Daridon

Fascio

Lichtenberg

et al. 2001

Fresenius J Anal Chem

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“…Bearing in mind the need for inexpensive components and the requirement of low-power operation, we have focused on colorimetric detection using LED/photodiode detection in a microfluidic manifold as a generic approach. So far two reagent methods have been identified as meeting the 12 month stability requirement (calibration slope should be better than 90% of the original slope after 12 months); the yellow method for orthophosphate [17], and the molybdenum blue or Bertholet method for ammonia [18]. Interestingly, the yellow method was found to be preferable to the more common indophenol method as the latter requires the use of ascorbic acid in the final reduction stage, which drastically limits the overall stability of the reagent cocktail.…”

Section: Reliabilitymentioning

confidence: 99%

Internet-Scale Chemical Sensing: Is It More Than a Vision?

Diamond

NATO Security Through Science Series

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In order to realise scalability of chemical sensors in extensively deployed wireless sensor networks, considerable materials challenges must be overcome. Conventional devices are currently far too expensive and unreliable for massive long-term field deployment. Cost can be driven down by imaginative approaches to transduction and instrument design. For example, we have produced a complete instrument based on LED measurement of colour changes that has sub-micromolar detection limits for a number of heavy metals for around $1.2 In its current form, the device also has a short distance wireless communications functionality and very low power consumption. However, chemical sensors capable of long-term reliability will require imaginative solutions to the key issue -how can the sensing films/membranes in chemical sensors maintain predictable characteristics in long term deployment?The vision of 'internet-scale sensing' will only be realised through advances in materials science and a complete rethink of how we do chemical sensing. For example, fully autonomous sensing platforms must be completely self-reliant in terms of power, communications, reagents and consumables. The sensor network must be self-sustaining, meaning that as individual nodes become unreliable, new nodes are established, for example through physical replacement or through devices capable of self-repair/regeneration. In this chapter, these issues are presented, along with some recent advances mentioned above.

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Biomass recycling from a riboflavin cultivation withB. subtilis: Lysis, extract production and testing as substrate in riboflavin cultivation

Bretz

Ilijevic

Grüneberg

et al. 2006

Biotechnol. Bioeng.

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Autolysis of riboflavin-producing B. subtilis can be induced by pH, lack of carbon source, and the buffer system. Stress factors like temperature shift or oxygen dearth enhance the autolysis process. After cultivation of a riboflavin-producing strain, the pH of the whole culture broth was adjusted to 6.5-7.5. At a temperature of 40 degrees C, autolysis started after 1 h. Adding a defined amount of commercially available endo- and exo-proteases enhanced both auto- and proteo-lysis. Optimization of endo- and exo-protease concentrations and of the time increased the degree of proteolysis. Additionally, the amount of DNA and Protein trapped in the riboflavin crystals could be significantly reduced by autolysis. After autolysis, the cultivation broth was centrifuged and the supernatant was cross-flow filtrated with a cut off of 10 kDa. Using this autolysate instead of yeast extract as a medium component for riboflavin production with B. subtilis, a riboflavin yield of 77% was obtained in comparison with the standard cultivation on yeast extract.

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Chemical sensing using an integrated microfluidic system based on the Berthelot reaction

Cited by 80 publications

References 26 publications

Multi-layer microfluidic glass chips for microanalytical applications

Multi-layer microfluidic glass chips for microanalytical applications

Internet-Scale Chemical Sensing: Is It More Than a Vision?

Biomass recycling from a riboflavin cultivation withB. subtilis: Lysis, extract production and testing as substrate in riboflavin cultivation

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