This article reports a novel strip-type microthrottle pump with a rectangular actuator geometry, with more efficient chip surface consumption compared to existing micropumps with circular actuators. Due to the complex structure and operation of the proposed device, determination of detailed structural parameters is essential. Therefore, we developed an advanced, fully coupled 3D electro-fluid-solid mechanics simulation model in COMSOL that includes fluid inertial effects and a hyperelastic model for PDMS and no-slip boundary condition in fluid-wall interface. Numerical simulations resulted in accurate virtual prototyping of the proposed device, detailed operation analysis and optimisation of cruical geometrical parameters.
COBISS.SI-ID: 9729620
Skin penetration efficacy by a silicon microneedle array (13x13 mm2) for drug delivery, each consisting of 100 microneedles, 200 µm high and fabricated by DRIE process, was investigated. To evaluate the penetration efficacy through the mechanically and electrically resistant upper skin layer of stratum corneum, the electrical skin impedance change with applied force was measured by using Au-coated Si microneedle array as working electrode. Results were analysed by Cole- Cole impedance plot and equivalent electrical circuit elements were determined. By implementation of impact assisted penetration method of microneedle array a significant impedance reduction was obtained, which is a strong evidence of successful skin penetration. Analyses of Si microneedle mechanical properties revealed that by proper use a safety margin )60 can be achieved.
COBISS.SI-ID: 11053652
Development, numerical optimization, and fabrication of piezoelectric microcylinder pumps are presented. Innovative design is based on a centrally placed inlet port which leads directly into the center of the pumping chamber. Unique features of microcylinder pumps were developed through virtual device prototyping, using an advanced 3D fully coupled electro-mechanical-fluidic (EMF) model built in COMSOL Multiphysics 4.3b simulation environment. To validate developed simulation model, microcylinder pumps with various pumping chamber diameters were fabricated employing soft lithography process. Optimized micropump prototype exhibits flow rates up to 2.3 ml min-1/8 ml min-1, backpressures up to 520 mbar/55 mbar, and suction pressures down to -480 mbar/-85 mbar for DI water and air, respectively. Furthermore, it features self-priming ability and high level of bubble tolerance.
COBISS.SI-ID: 11081812
High performance piezoelectric PDMS peristaltic micropump with a single actuator is presented that enables driving with less expensive and simpler singlephase controllers while maintaining all the superior properties of conventional peristaltic micropumps, such as robustness, simplicity and purity due to the absence of valves. Fabricated prototypes featured high water / air flowrate performance (up to 0.24 ml min-1/up to 0.84 ml min-1), backpressure performance (up to 360 mbar/up to 80 mbar) and suction pressure performance (down to -165 mbar/down to -140 mbar). Furthermore, bubble tolerance and selfpriming capability have been proved, together with valve regime of operation that enables sealing of the fluidic path when appropriate dc voltage is applied.
COBISS.SI-ID: 10790484
Thermal annealing of deposited Ti/Pt layers in the temperature range of 300-700 °C was investigated revealing strong impact on the Ti/Pt resistivity. Furthermore, it was determined that temperature coefficient of resistance (TCR) for Ti/Pt temperature sensors and the heater increased with the annealing temperature. Microstructural analysis of deposited and annealed Ti/Pt layers carried out by AES and AFM revealed that recrystallization followed by grain growth process of heat treated Ti/Pt layers started at around 500 °C and correlated well with the behavior of electrical properties. Additional insulation steps of assembled microfluidic platform further reduced the power consumption, but also increased the time response of the microfluidic reactor.
COBISS.SI-ID: 8160596
In this study we presented micro fabrication of silicon based fuel combustor with Pt/CeO2 catalyst. Ignition regimes for premixed methanol - O2 and methanol - air mixtures were studied. The obtained final temperature of the micro combustor strongly depends on the methanol partial pressure, residence time and the feed conditions. Autonomous combustor performance is demonstrated with an average liquid methanol feed rate of 1.45 ml h-1 at 320±2 °C.
COBISS.SI-ID: 9134420
We describe the development, fabrication and testing of a microfluidic chamber for dielectrophoretic field-flow separation of biological cells based on their electrical properties. The chamber was constructed from a single Pyrex wafer with interdigitated Au electrodes, a spacer, and a top cover glass, making the events in the chamber observable under most optical microscopes. The dimensions were optimized based on numerical computations of the electric field, its gradient and the fluid-flow velocity profile. A 93% efficiency of separation was obtained, confirming the usefulness of the chamber in separating cells with sufficient differences in electrical properties of their membranes.
COBISS.SI-ID: 8331860
In this work, solutions for the control of a built-in mechanical residual stress in the thin films of amorphous silicon, amorphous silicon carbide and amorphous silicon nitride obtained by chemical vapor deposition in plasma were shown. Process parameters analyzed were: deposition temperature, pressure, gas composition, low (20-100W) and high (100-600W) RF power and the frequency of the RF power (high-13.56 MHz or low-400kHz). It has been shown that the amorphous silicon nitride layer obtained at the low rf power still shows built-in tensile residual stress (in the order of 100 MPa) at high-frequency rf-power and built-in compressive residual stress (in the order -500 Mpa), if low-frequency rf-power were applied. The results showed that in this layer is possible to obtain virtually zero value of the built-in residual stress (4MPa) at high frequency RF power, whenever enough high rf-power was applied (600W). Also in the other deposited layers, it was observed that the frequency of the rf-power has the main contribution to residual stress in thin films due to ion bombardment.
COBISS.SI-ID: 8972116
Investigation of cutting edge properties in edge-on silicon microsystem has been performed. An advanced approach for reducing dead layer thickness has been introduced. Proposed approach is developed in such a way that no additional photolithographic process steps and critical handling with individual chips are needed after detector fabrication. Results presented in the paper show that this approach results in effective reduction of cutting edge thickness down to 50 µm. Such reduction of dead layer thickness, together with applied efficient current termination technique resulted in substantial improvement of detector structure performance.
COBISS.SI-ID: 7820884
Design and realization of a digitally controlled closed loop calibration system for smart sensors, capable of self-learning, is reported. Closed loop design enables analysis of sensor properties and optimization of calibration procedure. Dedicated software was developed, enabling control of acquired data and calibration procedure. Resulting statistical data provide closed loop feedback variable for failure analysis. Calibration system enables digital temperature compensation by acquisition of calibration points, calculation of sensor polynomial coefficients and storing the calculated data in the sensor memory. Due to the proposed digital temperature compensation method, temperature output error of pressure sensors was significantly reduced (typically from 0.15 %FSO/°C to 0.05 %FSO/°C, based on calibration of 29482 manifold absolute pressure sensors). Modular approach results in reduction of calibration time (typically down to 42 seconds/sensor), thus enabling mass calibration.
COBISS.SI-ID: 6446420