Optical sensor for seawater salinity

Huber, Christian; Klimant, Ingo; Krause, Christian; Werner, Tobias; Mayr, Torsten; Wolfbeis, Otto S.

doi:10.1007/s002160000493

Cited by 121 publications

(86 citation statements)

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“…For pHmeasurement, the fluorescence lifetime of a second indicator serves as a reference. This method, described by Huber et al (2000), is, therefore, called dual lifetime referencing. The measurement of DOT is based on dynamic luminescence quenching by molecular oxygen of the excited state of an indicator (Vanderkooi and Wilson, 1986).…”

Section: Microfluidic Biolectormentioning

confidence: 99%

Microfluidic biolector—microfluidic bioprocess control in microtiter plates

Funke

Buchenauer

Schnakenberg

et al. 2010

Biotech & Bioengineering

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In industrial-scale biotechnological processes, the active control of the pH-value combined with the controlled feeding of substrate solutions (fed-batch) is the standard strategy to cultivate both prokaryotic and eukaryotic cells. On the contrary, for small-scale cultivations, much simpler batch experiments with no process control are performed. This lack of process control often hinders researchers to scale-up and scale-down fermentation experiments, because the microbial metabolism and thereby the growth and production kinetics drastically changes depending on the cultivation strategy applied. While small-scale batches are typically performed highly parallel and in high throughput, large-scale cultivations demand sophisticated equipment for process control which is in most cases costly and difficult to handle. Currently, there is no technical system on the market that realizes simple process control in high throughput. The novel concept of a microfermentation system described in this work combines a fiber-optic online-monitoring device for microtiter plates (MTPs)--the BioLector technology--together with microfluidic control of cultivation processes in volumes below 1 mL. In the microfluidic chip, a micropump is integrated to realize distinct substrate flow rates during fed-batch cultivation in microscale. Hence, a cultivation system with several distinct advantages could be established: (1) high information output on a microscale; (2) many experiments can be performed in parallel and be automated using MTPs; (3) this system is user-friendly and can easily be transferred to a disposable single-use system. This article elucidates this new concept and illustrates applications in fermentations of Escherichia coli under pH-controlled and fed-batch conditions in shaken MTPs.

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Section: Microfluidic Biolectormentioning

confidence: 99%

Microfluidic biolector—microfluidic bioprocess control in microtiter plates

Funke

Buchenauer

Schnakenberg

et al. 2010

Biotech & Bioengineering

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Section: Et Al Invented a Novel Technique For Luminescence Decay Timmentioning

confidence: 99%

Development of microscopic time‐domain dual lifetime referencing luminescence detection for pH monitoring in microfluidic free‐flow isoelectric focusing

Poehler

Herzog

Suendermann

et al. 2015

Engineering in Life Sciences

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www.els-journal.com Page 3 Engineering in Life SciencesThis article is protected by copyright. All rights reserved. AbstractA lifetime-based ratiometric microscale pH sensor system and a fluorescence microscopic setup was developed for the in-line observation of pH in free-flow isoelectric focusing based on the principle of time-domain dual lifetime referencing (t-DLR). The t-DLR method has been developed for pH monitoring and various other applications in the fields of environmental monitoring and biotechnology. Here, we introduce the integration of pH sensor microstructures for t-DLR in microfluidic channels and the application of the t-DLR scheme for pH sensing in miniaturized electrophoretic procedures. The pH sensor was inkjet-printed on glass in rows with a length of 10 mm, a height of 404 ± 18 nm and a width of 371 ± 28 µm, and integrated into a microfluidic chip generated by a lasercutting and lamination technique. It had a working range from pH 4 to 8 with a pK A of 6.10 ± 0.01 and fast response times under 500 ms. The sensor was used for the in-line observation of the pH gradient during isoelectric focussing of the proteins β-lactoglobulin A, conalbumin and myoglobin and their identification by their isoelectric point (pI). The obtained pIs were in good agreement with literature data demonstrating the applicability of the pH sensor in microfluidic continuous separations.

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“…Both the indicator and reference dyes need to be immobilized with a defined molar ratio in the same matrix. Optimally, both dyes should be excited in the same spectral range, and the ratiometric referencing can be done either by spectral (facilitated by distinct emission spectra of the dyes) or temporal (enabled by distinct luminescence lifetimes of the dyes; , Huber et al 2000 separation of the 2 luminescence signals. To our knowledge, such ratiometric O 2 imaging has not yet been applied in environmental applications of planar optodes.…”

Section: O 2 Imaging Systems and Measuring Protocolsmentioning

confidence: 99%

Functional and structural imaging of phototrophic microbial communities and symbioses

Kühl¹,

Polerecký²

2008

Aquat. Microb. Ecol.

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In recent years, new imaging methods for mapping microhabitats, solute concentrations, microbial activity and photopigment content have been developed and increasingly applied in different areas of aquatic microbial ecology and biogeochemistry. Such techniques exhibit a spatial resolution similar to that of microsensors, but allow for instantaneous mapping of the 2-dimensional distribution and dynamics of solute and pigment concentrations over areas ranging from µm 2 to several cm 2 . Methods have been developed for imaging O 2 and CO 2 concentrations as well as pH with optical sensor foils (i.e. planar optodes), and for combined imaging of photopigments and photosynthetic activity via variable chlorophyll fluorescence. More recently, hyperspectral imaging has been employed to identify pigment content in individual cells and to visualize the spatial organization of functional groups in photosynthetic microbial communities. We give an overview of these emerging methods with a range of illustrative examples to demonstrate how they can provide useful information in functional and structural studies of a variety of aquatic microbial communities, such as sediments, biofilms, coral tissues or photosynthetic mats.

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Optical sensor for seawater salinity

Cited by 121 publications

References 0 publications

Microfluidic biolector—microfluidic bioprocess control in microtiter plates

Microfluidic biolector—microfluidic bioprocess control in microtiter plates

Development of microscopic time‐domain dual lifetime referencing luminescence detection for pH monitoring in microfluidic free‐flow isoelectric focusing

Functional and structural imaging of phototrophic microbial communities and symbioses

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