Sealed cylindrical microreservoir with upper wall made of flexible thin PDMS membrane was designed, fabricated and characterized. Soft-lithography technique by replica molding process was applied for reservoir fabrication. Pressure drop versus drained volume from reservoir and deflection of membrane were measured. Three specific regions in measurement of pressure drop were observed. It has been shown that 135 µm thick membrane of the reservoir made by high pre-polymer to curing agent mixing ratio (40:1) and cured at 200 °C for 20 minutes revealed high aging stability. Complete emptying the reservoir of diameter 10 mm and volume 590 µl needs suction pressure of a few tens of millibars.
COBISS.SI-ID: 11562068
A miniaturized packed bed reactor (MPBR) was developed using a sandwich-like structure, which enabled simple and efficient enzyme loading, easy assembly and reusability, as well as a variation of channel dimensions without tedious manufacturing procedures. LentiKats® with immobilized ω-transaminase were either uniformly or randomly packed within MPBRs channels, which were gradually increased regarding width and depth in order to study the influence of a scale-up on selected transamination process. MPBRs were further characterized and compared regarding volumetric productivity and pressure drop measured by a silicon piezoresistive pressure sensor. The highest volumetric productivity was achieved within the widest, milliliter-scale channel with a triangular inlet pre-chamber containing pillars and uniformly packed with a single layer of LentiKats®. Pressure drops of up to 42 kPa were measured within the microliter and milliliter-scale MPBRs tested in this study. Small pressure drop contributed also to the high operational stability of the tested MPBR with more than 80% retained initial volumetric productivity within 3 weeks of a continuous transamination process.
COBISS.SI-ID: 1537199299
A micro flowmeter for microfluidic applications was designed, fabricated and characterized for two measuring configurations. Three platinum resistance thermometers were inserted in casted PDMS before polymerization occurred. For highest flowmeter sensitivity and widest measuring range, heating elements were heated up to 80 °C. With respect to linearity of the response and the measuring range span, Heater/Sensor -Heater/Sensor measuring configuration was found as the most applicable one yielding response characteristic with a linear slope coefficient of 0.245 V min ml-1.
COBISS.SI-ID: 11561812
Experimental study of in vivo transdermal saline and insulin delivery by fabricated hollow silicon microneedle array (100 microneedles, 220 µm high) was carried out. Saline solution was delivered into the skin first to evaluate the transfer efficiency. Transfer efficiency was found to decrease significantly by increasing the saline delivery flow rate. Second part of experiments was performed by transdermal delivery of insulin by aid of microneedle array and syringe pump to a healthy human subject in-vivo followed by blood analyses. After insulin infusion the blood glucose level drop (5-7%) was determined by this approach of delivery.
COBISS.SI-ID: 11562324
We report on the development of WO3 materials (i.e layers and powders) with increased symmetry induced by the incorporation of titanium into a crystalline WO3 matrix. The IR spectroscopy and XRD analysis of layers and powders prepared by sol-gel synthesis heat-treated at 450°C proved that the presence of titanium ions induces ordering and increases the symmetry of WO6 octahedra in the WO3 crystalline matrix leading to the transformation of the cell symmetry from monoclinic through tetragonal up to the cubic. Cyclic voltammetry confirmed that this increased symmetry leads to an up-shift in redox potential, which favors the coloration of the layers in photochromic devices. According to our knowledge, this is the first report of colorless cubic WO3 layers, which have potential applications in optoelectronic devices, catalysts and sensors.
COBISS.SI-ID: 11351892