| 1. |
- Danielsson, B., et al.
(författare)
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Recent investigations on calorimetric biosensors
- 1992
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Ingår i: Sensors and Actuators B: Chemical. - 0925-4005. ; 6:1-3, s. 138-142
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Tidskriftsartikel (refereegranskat)abstract
- New applications of a flow-calorimetric biosensor system, the enzyme thermistor (ET) are described. The ET measures the reaction heat in a small column containing immobilized biocatalyst as a temperature change of the effluent from the column. Since most biological reactions are exothermic, the ET has a very broad applicability and numerous assays of clinical as well as biotechnological interest have been studied. The procedure is well suited for monitoring and control of biotechnological processes due to its high operational stability. New results from this area are presented as well as developments on an automated thermometric immunoassay (TELISA). Miniaturized ET devices are suitable for portable monitoring of, for instance, blood glucose. Other recent work includes determinations in organic solvents, direct characterization of immobilized biocatalysts and monitoring of bioactivities in solution.
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| 2. |
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| 3. |
- Svanberg, Sune
(författare)
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Chemical sensing with laser spectroscopy
- 1996
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Ingår i: Sensors and Actuators B: Chemical. - : Elsevier BV. - 0925-4005. ; 33:1-3, s. 1-4
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Tidskriftsartikel (refereegranskat)abstract
- Laser spectroscopic techniques constitute powerful tools for chemical sensing. Atoms and molecules can be identified and quantified by their specific spectral signatures and the strength of the signals. A wide variety of methods for establishing spectroscopic contact with the species exist: absorption, emission, fluorescence, Raman scattering, acousto-optic, and opto-galvanic phenomena can be employed. Extreme sensitivity and specificity characterise the methods, which can be used for in situ monitoring and in some cases, for remote sensing. Through the special properties of laser radiation it is particularly simple to combine laser spectroscopy with fibre-optical techniques.
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| 4. |
- Xie, Bin, et al.
(författare)
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Development of a thermal micro-biosensor fabricated on a silicon chip
- 1992
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Ingår i: Sensors and Actuators B: Chemical. - 0925-4005. ; 6:1-3, s. 127-130
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Tidskriftsartikel (refereegranskat)abstract
- In order to develop a sensitive, versatile and inexpensive portable instrument, a calorimetric micro-biosensor was designed and fabricated by etching part of the flow system into a silicon wafer. The utility of the device was tested using the enzymes, catalase and penicillinase. This sensor showed good reproducibility and linearity up to 100 mM. The system also showed higher sensitivity than the conventional enzyme thermistor (ET) when identical sample volumes (20 μl) were applied. Finally, future prospects in this field are discussed.
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| 5. |
- Xie, Bin, et al.
(författare)
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Fast determination of whole blood glucose with a calorimetric micro-biosensor
- 1993
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Ingår i: Sensors and Actuators B: Chemical. - 0925-4005. ; 15:1-3, s. 141-144
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Tidskriftsartikel (refereegranskat)abstract
- Fast determination of whole blood glucose without any pretreatment was achieved using a calorimetric FIA micro-biosensor. Glucose oxidase was covalently immobilized, together with catalase, onto controlled pore glass beads and packed into a micro-column. By reducing the sample volume down to 1 μ1, a measurement period of about 40 s and an enlarged linear range of 0.5-20 mM glucose were obtained. The correlation coefficient was 0.98 when the micro-biosensor was compared to the Reflolux-S blood glucose analyser. The relative standard deviation for 100 blood samples was 3.7%.
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| 6. |
- Xie, Bin, et al.
(författare)
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Miniaturized thermal biosensors
- 1993
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Ingår i: Sensors and Actuators B: Chemical. - 0925-4005. ; 16:1-3, s. 443-447
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Tidskriftsartikel (refereegranskat)abstract
- Miniaturized thermal biosensors based on three different designs have been constructed. Properties relevant to decentralized bioanalysis have been investigated. A short measurement period (30 s per sample) and a broad linear range (0.5 mM to 100 mM for glucose and penicillin-V), using 1 μl sample volume, have been achieved.
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| 7. |
- Jager, Edwin, 1973-, et al.
(författare)
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On-chip microelectrodes for electrochemistry with moveable PPy bilayer actuators as working electrodes
- 1999
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Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 56:1-2, s. 73-78
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Tidskriftsartikel (refereegranskat)abstract
- We present electrochemical microactuators which have all the electrodes necessary for the actuation—the working, counter, and reference electrodes—on-chip. This is a first step towards an all-polymer system, i.e., a system that does not require a liquid electrolyte. The microactuators' performance was as good as when standard, off-chip counter and reference electrodes were used. Specifically, the speed of actuation was the same. In addition, we obtained a good cyclic voltammogram, although the oxidation and reduction peaks were shifted and some noise was present. Apart from application in an all-polymer system, we will also use these microactuators for studies on the effect of mechanical stimulation of living cells.
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| 8. |
- Abom, A.E., et al.
(författare)
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Experimental evidence for a dissociation mechanism in NH3 detection with MIS field-effect devices
- 2003
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Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 89:1-2
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Tidskriftsartikel (refereegranskat)abstract
- The gas response mechanism of ammonia detection with Pt-based metal-insulator-semiconductor (MIS) field-effect sensors was investigated. An experimental model system was designed which compares the responses of thick continuous Pt layers with controlled morphology and surface chemical composition, with the response of thin, discontinuous layers. The surface of a thick, continuous sputter-deposited Pt film is modified, either by (i) the deposition of a thin SiO2 overlayer, (ii) reactive sputter deposition of PtOx, or (iii) co-deposition of Pt with SiO2 in Ar + O2 atmospheres. We show that the ammonia response is caused by the formation of atomic hydrogen through the dissociation of NH3 at temperatures <200 °C. It is found that the modified surfaces exhibit increased ammonia selectivity compared to a pure Pt film. Results from this work indicate that the reason for the changed selectivity is the appearance of an oxidized PtOx phase or triple phase boundaries between Pt, SiO2 and the ambient gas, rather than for solely morphological reasons. © 2002 Elsevier Science B.V. All rights reserved.
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| 9. |
- Abom, A.E., et al.
(författare)
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Thin oxide films as surface modifiers of MIS field effect gas sensors
- 2002
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Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 85:1-2, s. 109-119
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Tidskriftsartikel (refereegranskat)abstract
- The catalytic activity at the surface of Pt based MIS field effect gas sensors is modified by the deposition of thin films of SnO2, Al2O3 and SiO2, grown by reactive sputtering. It is found that a very thin layer (<10 nm) of SiO2 and SnO2 changes the catalytic activity towards higher NH3 selectivity, but with thicker films the sensor response vanishes. Since the response mechanism for these sensors is dependent on dissociation of molecules, it is likely that at low temperatures (140 °C), neither dissociation on nor transport/diffusion through the thicker films takes place. However, with Pt in conjunction with SiO2 or SnO2, the surface reactions will be altered, with enhanced NH3 selectivity as a result. A thin film of Al2O3, on the other hand, has a much smaller influence on the gas response to the test gases used in this work. Furthermore the sputtering process is found to strongly influence the sensor responses, and specifically reduce the sensitivity of the sensor. A thin intermediate layer of evaporated Pt does not completely protect the underlying structure from sputter induced damage. © 2002 Elsevier Science B.V. All rights reserved.
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| 10. |
- Andersson, Helene, et al.
(författare)
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A valve-less diffuser micropump for microfluidic analytical systems
- 2001
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Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 72:3, s. 259-265
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Tidskriftsartikel (refereegranskat)abstract
- The suitability of valve-less micropumps in biochemistry has been shown. Fluids encountered in various biochemical methods that are problematic for other micropumps have been pumped with good performance. The pump is fabricated as a silicon-glass stack with a new process involving three subsequent deep reactive ion etching steps. Some of the main advantages of the valve-less diffuser pump are the absence of moving parts (excluding the pump diaphragm), the uncomplicated planar design, and high pump performance in terms of pressure head and flow rare. In addition, the micropump is self-priming and insensitive to particles and bubbles present in the pumped media. The results show that the valve-less micropump successfully pumps fluids within the viscosity range of 0.001-0.9 N s/m(2). The micropump is not sensitive to the density, ionic strength, or pH of the pumped media. Effective pumping of solutions containing beads of different sizes was also demonstrated. Living cells were pumped without inducing cell damage and no cell adhesion within the pump chamber was found. No valve-less micropump has previously been reported to pump such a wide variety of fluids.
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