Started in 2003 and originally called USWNet, the Acoustofluidics conference series offers an ann... more Started in 2003 and originally called USWNet, the Acoustofluidics conference series offers an annual international meeting place for researchers interested in all aspects of ultrasound in microfluidics. It covers topics including ultrasonic standing wave technology and surface acoustic wave devices for particle, bubble and fluid manipulation, and ranges from fundamental theory and physics to
In this thesis two techniques, namely Raman spectroscopy and ultrasound particle manipulation, ha... more In this thesis two techniques, namely Raman spectroscopy and ultrasound particle manipulation, have been successfully combined to achieve a powerful analytical measurement technology for the acquisition of Raman spectra of PMMA particles in suspension in order to increase sensitivity of Raman spectroscopy.
In this work, we demonstrate our activities towards the combination of an ultrasound (<br> ... more In this work, we demonstrate our activities towards the combination of an ultrasound (<br> enhanced ATR IR setup for analysis of bacteria in water For samples containing low bacteria<br> levels, US enhanced ATR IR spectroscopy poses an interesting approach, because the<br> standing ultrasonic wave ( can be used in a first step for accumulation of the bacteria in<br> the sample cell Subsequently, the enriched bacteria solution is forced towards the ATR<br> element for interaction with the evanescent wave
In this work, we present our activities towards the development of an ultrasound (<br> enha... more In this work, we present our activities towards the development of an ultrasound (<br> enhanced attenuated total reflection infrared (ATR IR) setup for analysis of bacteria in water<br> For investigations of samples containing low bacteria levels, US enhanced ATR IR<br> spectroscopy poses an interesting approach, because ultrasound particle manipulation can be<br> used for accumulation of the bacteria within the acoustofluidic cell Subsequently, the resulting<br> bacteria conglomerates can be observed via ATR IR spectroscopy In an alternative approach,<br> a bead based assay implementing ultrasound particle manipulation, was realized to improve<br> the sensitivity of the US ATR IR sensor The potential of an US ATR IR setup has been<br> demonstrated in earlier works by trapping biotechnological relevant particles (e g yeast,<br> Escherichia coli in the evanescent field of an ATR probe employing ultrasound particle<br> manipu...
Die Ultraschallfalle soniccatch konzentriert biologische Zellen, Mikroplastik und Schwebstoffe gl... more Die Ultraschallfalle soniccatch konzentriert biologische Zellen, Mikroplastik und Schwebstoffe gleichermaßen. Die Methode könnte Felduntersuchungen der Mikroplastikbelastung in Gewässern ermöglichen.
A thermostabilized aluminium acoustic trap combined with attenuated total reflection infrared spe... more A thermostabilized aluminium acoustic trap combined with attenuated total reflection infrared spectroscopy used to perform ultrasound-assisted E. coli detection.
L'invention concerne un dispositif (1) de spectroscopie d'absorption FTIR comportant un c... more L'invention concerne un dispositif (1) de spectroscopie d'absorption FTIR comportant un capteur ATR (5) ainsi qu'au moins un emetteur d'ultrasons (10) servant a generer un champ ultrasonore de la nature d'une onde stationnaire, le capteur ATR (5) et l'emetteur d'ultrasons (10) etant relies a un element de retenue (4) concu pour etre monte dans une paroi (2) ou dans le toit d'un reacteur (3) et configure pour maintenir librement le capteur ATR (5) et l'emetteur d'ultrasons (10) penetrant a l'interieur du reacteur (3) a l'etat monte.
Retention and manipulation of microbial cells through exploitation of ultrasonic forces has been ... more Retention and manipulation of microbial cells through exploitation of ultrasonic forces has been reported as a novel cell immobilisation technique. The spatial ordering of yeast cells, within suspensions subjected to an ultrasonic standing wave field, was analysed for the first time. A technique, based on `freezing' the spatial arrangement using polymer gelation was developed. The resultant gel was then sectioned
Bacillus subtilis is a single celled bacterium commonly found in soil. It can sporulate, i.e. rev... more Bacillus subtilis is a single celled bacterium commonly found in soil. It can sporulate, i.e. reversibly form a tough and protective endospore that allows the organism to tolerate extreme environmental conditions. B. subtilis is not harmful to human health and its robust spores may therefore serve as safe model organisms for pathogenic microorganisms in drinking water. Thus, this organism can be used to monitor the quality of water disinfection devices that utilize UV radiation. One type of B. subtilis spores is highly resistant to UV irradiation, whereas the other type shows a low UV resistance. Biotechnological methods used are ultrasonic treatment for separating cells from nutrient solution and inducing sporulation in vegetative B. subtilis by induction of adverse environmental conditions, such as shortage of certain nutrients. Intermittent contact atomic force microscopy mode (using an MFP- 3D from Asylum research, Santa Barbara, CA, USA) was used to discern vegetative bacteria ...
One important niche for multi-wavelength resonators is the filtration of suspensions containing v... more One important niche for multi-wavelength resonators is the filtration of suspensions containing very high particle concentration. For some applications, multi-wavelength ultrasound enhanced sedimentation filters are second only to the centrifuge in efficiency but, unlike the centrifuge they are easily adapted for continuous flow. Multi-wavelength resonators are also an obvious consideration when half-wavelength chambers are too small for a specific application. Unfortunately the formula, bigger = higher-throughput, does not scale linearly. Here we describe the relationships between chamber size and throughput for acoustic, electrical, flow and thermal convection actions, allowing the user to define initial parameters for their specific applications with some confidence. We start with a review of some of the many forms of multi-wavelength particle manipulation systems.
European Journal of Lipid Science and Technology, 2010
ABSTRACT The yeast Candida bombicola ATCC 22214 is well-known to produce mixtures of glycolipids ... more ABSTRACT The yeast Candida bombicola ATCC 22214 is well-known to produce mixtures of glycolipids containing the sugar sophorose, the so-called sophorolipids, especially when cultivated on hydrophobic carbon sources as co-substrates. To improve cultivation efficiency, an integrated process was developed using ultrasound separation technology. Since this technology is new for use with C. bombicola, it was first characterized in batch experiments and afterwards implemented in an integrated production process. In this process, separation efficiencies of about 99% C. bombicola cells could be achieved, leading to 8 g/L of nearly cell-free sophorolipid product and a total amount of 73.8 g/L sophorolipids. Furthermore, a technical mixture of unusual branched fatty alcohols containing mainly 2-hexyl-1-decanol was used as co-substrate with glucose in a shake flask study. This resulted in the production of a new product, 1-O-β-glucopyranosyl-2-hexyldecanol, a molecule containing glucose as the sugar moiety and 2-hexyl-1-decanol as a branched hydrophobic side chain.
Started in 2003 and originally called USWNet, the Acoustofluidics conference series offers an ann... more Started in 2003 and originally called USWNet, the Acoustofluidics conference series offers an annual international meeting place for researchers interested in all aspects of ultrasound in microfluidics. It covers topics including ultrasonic standing wave technology and surface acoustic wave devices for particle, bubble and fluid manipulation, and ranges from fundamental theory and physics to
In this thesis two techniques, namely Raman spectroscopy and ultrasound particle manipulation, ha... more In this thesis two techniques, namely Raman spectroscopy and ultrasound particle manipulation, have been successfully combined to achieve a powerful analytical measurement technology for the acquisition of Raman spectra of PMMA particles in suspension in order to increase sensitivity of Raman spectroscopy.
In this work, we demonstrate our activities towards the combination of an ultrasound (<br> ... more In this work, we demonstrate our activities towards the combination of an ultrasound (<br> enhanced ATR IR setup for analysis of bacteria in water For samples containing low bacteria<br> levels, US enhanced ATR IR spectroscopy poses an interesting approach, because the<br> standing ultrasonic wave ( can be used in a first step for accumulation of the bacteria in<br> the sample cell Subsequently, the enriched bacteria solution is forced towards the ATR<br> element for interaction with the evanescent wave
In this work, we present our activities towards the development of an ultrasound (<br> enha... more In this work, we present our activities towards the development of an ultrasound (<br> enhanced attenuated total reflection infrared (ATR IR) setup for analysis of bacteria in water<br> For investigations of samples containing low bacteria levels, US enhanced ATR IR<br> spectroscopy poses an interesting approach, because ultrasound particle manipulation can be<br> used for accumulation of the bacteria within the acoustofluidic cell Subsequently, the resulting<br> bacteria conglomerates can be observed via ATR IR spectroscopy In an alternative approach,<br> a bead based assay implementing ultrasound particle manipulation, was realized to improve<br> the sensitivity of the US ATR IR sensor The potential of an US ATR IR setup has been<br> demonstrated in earlier works by trapping biotechnological relevant particles (e g yeast,<br> Escherichia coli in the evanescent field of an ATR probe employing ultrasound particle<br> manipu...
Die Ultraschallfalle soniccatch konzentriert biologische Zellen, Mikroplastik und Schwebstoffe gl... more Die Ultraschallfalle soniccatch konzentriert biologische Zellen, Mikroplastik und Schwebstoffe gleichermaßen. Die Methode könnte Felduntersuchungen der Mikroplastikbelastung in Gewässern ermöglichen.
A thermostabilized aluminium acoustic trap combined with attenuated total reflection infrared spe... more A thermostabilized aluminium acoustic trap combined with attenuated total reflection infrared spectroscopy used to perform ultrasound-assisted E. coli detection.
L'invention concerne un dispositif (1) de spectroscopie d'absorption FTIR comportant un c... more L'invention concerne un dispositif (1) de spectroscopie d'absorption FTIR comportant un capteur ATR (5) ainsi qu'au moins un emetteur d'ultrasons (10) servant a generer un champ ultrasonore de la nature d'une onde stationnaire, le capteur ATR (5) et l'emetteur d'ultrasons (10) etant relies a un element de retenue (4) concu pour etre monte dans une paroi (2) ou dans le toit d'un reacteur (3) et configure pour maintenir librement le capteur ATR (5) et l'emetteur d'ultrasons (10) penetrant a l'interieur du reacteur (3) a l'etat monte.
Retention and manipulation of microbial cells through exploitation of ultrasonic forces has been ... more Retention and manipulation of microbial cells through exploitation of ultrasonic forces has been reported as a novel cell immobilisation technique. The spatial ordering of yeast cells, within suspensions subjected to an ultrasonic standing wave field, was analysed for the first time. A technique, based on `freezing' the spatial arrangement using polymer gelation was developed. The resultant gel was then sectioned
Bacillus subtilis is a single celled bacterium commonly found in soil. It can sporulate, i.e. rev... more Bacillus subtilis is a single celled bacterium commonly found in soil. It can sporulate, i.e. reversibly form a tough and protective endospore that allows the organism to tolerate extreme environmental conditions. B. subtilis is not harmful to human health and its robust spores may therefore serve as safe model organisms for pathogenic microorganisms in drinking water. Thus, this organism can be used to monitor the quality of water disinfection devices that utilize UV radiation. One type of B. subtilis spores is highly resistant to UV irradiation, whereas the other type shows a low UV resistance. Biotechnological methods used are ultrasonic treatment for separating cells from nutrient solution and inducing sporulation in vegetative B. subtilis by induction of adverse environmental conditions, such as shortage of certain nutrients. Intermittent contact atomic force microscopy mode (using an MFP- 3D from Asylum research, Santa Barbara, CA, USA) was used to discern vegetative bacteria ...
One important niche for multi-wavelength resonators is the filtration of suspensions containing v... more One important niche for multi-wavelength resonators is the filtration of suspensions containing very high particle concentration. For some applications, multi-wavelength ultrasound enhanced sedimentation filters are second only to the centrifuge in efficiency but, unlike the centrifuge they are easily adapted for continuous flow. Multi-wavelength resonators are also an obvious consideration when half-wavelength chambers are too small for a specific application. Unfortunately the formula, bigger = higher-throughput, does not scale linearly. Here we describe the relationships between chamber size and throughput for acoustic, electrical, flow and thermal convection actions, allowing the user to define initial parameters for their specific applications with some confidence. We start with a review of some of the many forms of multi-wavelength particle manipulation systems.
European Journal of Lipid Science and Technology, 2010
ABSTRACT The yeast Candida bombicola ATCC 22214 is well-known to produce mixtures of glycolipids ... more ABSTRACT The yeast Candida bombicola ATCC 22214 is well-known to produce mixtures of glycolipids containing the sugar sophorose, the so-called sophorolipids, especially when cultivated on hydrophobic carbon sources as co-substrates. To improve cultivation efficiency, an integrated process was developed using ultrasound separation technology. Since this technology is new for use with C. bombicola, it was first characterized in batch experiments and afterwards implemented in an integrated production process. In this process, separation efficiencies of about 99% C. bombicola cells could be achieved, leading to 8 g/L of nearly cell-free sophorolipid product and a total amount of 73.8 g/L sophorolipids. Furthermore, a technical mixture of unusual branched fatty alcohols containing mainly 2-hexyl-1-decanol was used as co-substrate with glucose in a shake flask study. This resulted in the production of a new product, 1-O-β-glucopyranosyl-2-hexyldecanol, a molecule containing glucose as the sugar moiety and 2-hexyl-1-decanol as a branched hydrophobic side chain.
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Papers by Stefan Radel