Monte Carlo Simulation of Secondary Fluorescence in Small Particles and at Phase Boundaries

Llovet, Xavier; Valovirta, Eero; Heikinheimo, E.

doi:10.1007/s006040050013

Cited by 53 publications

(17 citation statements)

References 1 publication

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“…This was probably due to errors in our knowledge of the pH of the secondary standards and the fact that these solutions are not very stable over time because they are only weakly buffered by carbonate equilibria at near-seawater concentrations and may have changed slightly between spectrophotometric analyses and electrode measurement. Sandifer and Voycheck (1999) found that the Nernst slope of the Durafet held constant over 3 months (within the resolution of their measurements). We verified Nernstian behavior by comparing results of temperature cycling tests, but have not yet tested for changes in the pH response slope over several months as done by Sandifer and Voycheck (1999).…”

Section: Pts= E(t Ph ) E (T ) -E(t Ph ) -E (T )mentioning

confidence: 64%

“…Sandifer and Voycheck (1999) found that the Nernst slope of the Durafet held constant over 3 months (within the resolution of their measurements). We verified Nernstian behavior by comparing results of temperature cycling tests, but have not yet tested for changes in the pH response slope over several months as done by Sandifer and Voycheck (1999). Using data over the full temperature range 5 to 35°C (same data discussed below in Table 1), we calculated PTS INT = 99.5 ± 0.7% and PTS EXT = 98.6 ± 0.3%.…”

Section: Pts= E(t Ph ) E (T ) -E(t Ph ) -E (T )mentioning

confidence: 64%

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Testing the Honeywell Durafet® for seawater pH applications

Martz

Connery²,

Johnson

2010

Limnology & Ocean Methods

255

244

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We report on the first seawater tests at 1 atm of the Honeywell Durafet ® pH sensor, a commercially available ion sensitive field effect transistor (ISFET). Performance of this sensor was evaluated in a number of different situations including a temperature-controlled calibration vessel, the MBARI test tank, shipboard underway mapping, and a surface mooring. Many of these tests included a secondary reference electrode in addition to the internal reference supplied with the stock Durafet sensor. We present a theoretical overview of sensor response using both types of reference electrode. The Durafet sensor operates with a short term precision of ± 0.0005 pH over periods of several hours and exhibits stability of better than 0.005 pH over periods of weeks to months. Our tests indicate that the Durafet pH sensor operates at a level of performance satisfactory for many types of biogeochemical studies at low pressure. *Corresponding author: E-mail: trmartz@ucsd.edu AcknowledgmentsThis work was supported by grants from the David and Lucile Packard Foundation and the National Science Foundation through the Biocomplexity in the Environment Program Grant ECS-0308070 and the Ocean Technology and Interdisciplinary Coordination Program Grant OTIC-0844394. We thank Bob Carlson at Honeywell Laboratories for many helpful discussions throughout this work and for a critical review of the manuscript. Gernot Friederich provided underway TCO 2 and pCO 2 data. Hans Jannasch, Luke Coletti, Tom Marion, and Jim Montgomery facilitated construction of the autonomous Durafet sensor. Ginger Elrod, Steve Fitzwater, and Carole Sakamoto performed spectrophotometric pH measurements on test tank samples.

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Section: Pts= E(t Ph ) E (T ) -E(t Ph ) -E (T )mentioning

confidence: 64%

Section: Pts= E(t Ph ) E (T ) -E(t Ph ) -E (T )mentioning

confidence: 64%

Testing the Honeywell Durafet® for seawater pH applications

Martz

Connery²,

Johnson

2010

Limnology & Ocean Methods

255

244

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show abstract

“…the pH ISFET, is today a commercial reality (pH ISFETs are available from Orion, Beckman, Sentron, Honeyweel, Chem-FET Corporation, etc.) 134 and produced by silicon integrated technology. Therefore, for the fabrication of truly inexpensive and thus disposable biosensors, it is of great interest to manufacture the enzyme-containing layers also in batch processes.…”

Section: Enfetmentioning

confidence: 99%

Recent advances in biologically sensitive field-effect transistors (BioFETs)

Schöning

Poghossian

2002

Analyst

542

339

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“…As usual in bioprocesses, pH is measured using glass electrodes or optical pH probes [79]. An ion-specific field effect transistor (ISFET) pH probe (for a review of ISFET sensors, see [80]) has been used in a wireless sensor network for monitoring algae cultivations because of its reliability through robustness and stability [81].…”

Section: Phmentioning

confidence: 99%

Monitoring of Microalgal Processes

Havlík

Scheper

Reardon

2015

Microalgae Biotechnology

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Process monitoring, which can be defined as the measurement of process variables with the smallest possible delay, is combined with process models to form the basis for successful process control. Minimizing the measurement delay leads inevitably to employing online, in situ sensors where possible, preferably using noninvasive measurement methods with stable, low-cost sensors. Microalgal processes have similarities to traditional bioprocesses but also have unique monitoring requirements. In general, variables to be monitored in microalgal processes can be categorized as physical, chemical, and biological, and they are measured in gaseous, liquid, and solid (biological) phases. Physical and chemical process variables can be usually monitored online using standard industrial sensors. The monitoring of biological process variables, however, relies mostly on sensors developed and validated using laboratory-scale systems or uses offline methods because of difficulties in developing suitable online sensors. Here, we review current technologies for online, in situ monitoring of all types of process parameters of microalgal cultivations, with a focus on monitoring of biological parameters. We discuss newly introduced methods for measuring biological parameters that could be possibly adapted for routine online use, should be preferably noninvasive, and are based on approaches that have been proven in other bioprocesses. New sensor types for measuring physicochemical parameters using optical methods or ion-specific field effect transistor (ISFET) sensors are also discussed. Reviewed methods with online implementation or online potential include measurement of irradiance, biomass concentration by optical density and image analysis, cell count, chlorophyll fluorescence, growth rate, lipid concentration by infrared spectrophotometry, dielectric scattering, and nuclear magnetic resonance. Future perspectives are discussed, especially in the field of image analysis using in situ microscopy, infrared spectrophotometry, and software sensor systems.

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Monte Carlo Simulation of Secondary Fluorescence in Small Particles and at Phase Boundaries

Cited by 53 publications

References 1 publication

Testing the Honeywell Durafet® for seawater pH applications

Testing the Honeywell Durafet® for seawater pH applications

Recent advances in biologically sensitive field-effect transistors (BioFETs)

Monitoring of Microalgal Processes

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