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- Bodén, Roger, et al.
(författare)
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On-chip liquid storage and dispensing for lab-on-a-chip applications
- 2008
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Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 18:7, s. 075036-
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Tidskriftsartikel (refereegranskat)abstract
- This work presents novel components for on-chip storage and dispensing inside a lab-on-a-chip (LOC) for applications in immunoassay point-of-care testing (POCT), where incubation and washing steps are essential. It involves easy-to-use on-chip solutions for the sequential thermo-hydraulic actuation of liquids. The novel concept of combining the use of a rubber plug, both as a non-return valve cap and as a liquid injection interface of a sealed reservoir, allows simple filling of a sterilized cavity, as well as the storage and dispensing of reagent and washing buffer liquids. Segmenting the flow with air spacers enables effective rinsing and the use of small volumes of on-chip stored liquids. The chip uses low-resistance resistors as heaters in the paraffin actuator, providing the low-voltage actuation that is preferred for handheld battery driven instruments.
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- Dahlin, Andreas P, et al.
(författare)
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Multiplexed quantification of proteins adsorbed to surface-modified and non-modified microdialysis membranes
- 2012
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Ingår i: Analytical and Bioanalytical Chemistry. - : Springer Science and Business Media LLC. - 1618-2642 .- 1618-2650. ; 402:6, s. 2057-2067
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Tidskriftsartikel (refereegranskat)abstract
- A simple and straightforward method for discovery and quantification of proteins adsorbed onto delicate and sensitive membrane surfaces is presented. The adsorbed proteins were enzymatically cleaved while still adsorbed onto the membranes using an on-surface enzymatic digestion (oSED). This was followed by isobaric tagging, nanoliquid chromatography, and tandem mass spectrometry. Protein adsorption on tri-block copolymer Poloxamer 407 surface-modified microdialysis (MD) membranes were compared with protein adsorption on unmodified MD membranes. Ventricular cerebrospinal fluid (vCSF) kept at 37 °C was used as sample matrix. In total, 19 proteins were quantified in two biological replicates. The surface-modified membranes adsorbed 33% less proteins than control membranes and the most abundant proteins were subunits of hemoglobin and clusterin. The adsorption of clusterin on the modified membranes was on average 36% compared to control membranes. The most common protein in vCSF, Albumin, was not identified adsorbed to the surface at all. It was also experimentally verified that oSED, in conjunction with tandem mass spectrometry can be used to quantify femtomole amounts of proteins adsorbed on limited and delicate surfaces, such as MD membranes. The method has great potential and can be used to study much more complex protein adsorption systems than previously reported.
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- Lehto, Marcus, et al.
(författare)
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A polymeric paraffin microactuator
- 2008
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Ingår i: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 17:5, s. 1172-1177
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Tidskriftsartikel (refereegranskat)abstract
- Paraffin wax is a promising material in microactuators not only because of its ability of producing large displacements and high forces at the same time but also because of the variety of manufacturing techniques available. In this paper, a simple actuator based on paraffin wax as the active material is fabricated and tested. Ultraviolet-curable epoxy is used in a technique combining simultaneous moulding and liquid-phase photopolymerization in a single-process step to build the stiff part of the actuator body. A heater is integrated in the paraffin reservoir, and a polyimide tape is used as the deflecting membrane. Thermornechanical analysis of the paraffin wax shows that it exhibits a volume expansion of 10%, including phase transitions and linear expansion. As for the actuator, a stroke of 90 mu m is obtained for the unloaded device, whereas 37 mu m is recorded with a 0.5-N contact load at a driving voltage of 0.71 V and a frequency of 1/32 Hz. The actuator can be used in microsystems, where both large strokes and forces are needed. The low-cost materials and low driving voltage also makes it suitable for disposable systems.
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- Lehto, Marcus, 1973-
(författare)
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Paraffin Actuators in Microfluidic Systems
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- There is a need for reliable valves and pumps in microfluidics. A good microactuator is the key for low cost and high performance of these components.Paraffin wax is a promising material to be used as actuator material as is can produce large forces and large strokes. Further, the material is inexpensive and, none the less, the thermal heating of the material can be made with low voltages. All these properties are of interest in flow control components in microfluidics, and especially for disposables and in potable systems.In this work, paraffin wax has been used in devices and concepts. A valve for high-pressures, a peristaltic pump, a multi-stable actuator, and injector has been shown. A material study was performed on binary mixtures of pure paraffin (n-alkanes), and a concept for loading fluid into a sealed reservoir was shown as well. Several injectors were demonstrated in a Lab-on-a-chip system with other microfluidic components.High pressure applications in microfluidics along with the multi-stable actuator show good potential. However, the drive and control has to be further developed.
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