Direct laser printing of thin-film polyaniline devices

We report the fabrication of electrically functional polyaniline thin-film microdevices. Polyaniline films were printed in the solid phase by Laser Induced Forward Transfer directly between Au electrodes on a Si/SiO2 substrate. To apply solid-phase deposition, aniline was in situ polymerized on quartz substrates. Laser deposition preserves the morphology of the films and delivers sharp features with controllable dimensions. The electrical characteristics of printed polyaniline present ohmic behavior, allowing for electroactive applications. Results on gas sensing of ammonia are presented.Comment: In Pres

Fabrication and modeling of a continuous-flow microfluidic device for on-chip DNA amplification

This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.The fabrication process and heat transfer computations for a continuous flow microfluidic device for DNA amplification by polymerase chain reaction (PCR) are described. The building blocks are thin polymeric materials aiming at a low cost and low power consumption device. The fabrication is performed by standard pattern transfer techniques (lithography and etching) used for microelectronics fabrication. The DNA sample flows in a meander shaped microchannel formed on a 100μm thick polyimide (PI) layer through three temperature regions defined by the integrated resistive heaters. The heat transfer computations are performed in a unit cell of the device. They show that, for the fabricated device, the variation of the temperature inside the channel zones where each step (denaturation, annealing, or extension) of PCR occur is less than 1.3K. This variation increases when the thickness of the PI layer increases. The computations also show that similar Silicon-based devices lead to lower temperature difference between the heaters and the DNA sample compared to the polymer-based fabricated device. However, the power consumption is estimated much greater for Silicon-based devices.This work was co-financed by Hellenic Funds and by the European Regional Development Fund (ERDF) under the Hellenic National Strategic Reference Framework (NSRF) 2007-2013, according to Contract no. MICRO2-45 of the Project “Microelectronic Components for Lab-on-chip molecular analysis instruments for genetic and environmental applications” within the Programme "Hellenic Technology Clusters in Microelectronics – Phase-2 Aid Measure"

A fabrication process of flexible IDE capacitive chemical sensors using a two step lift-off method based on PVA patterning

A versatile, two-step, lift-off method, for the fabrication of flexible capacitive chemical sensors based on interdigitated electrodes (IDEs) is presented. A Polyimide (PI) foil whose one side is coated with a thin Aluminum (Al) film is used as the sensor substrate. The IDEs are then formed on the Al film using conventional semiconductor processes. Precise patterning of the sensor sensing layer, on the surface of the Al IDEs, is achieved using a two-step lift-off process which involves a first lift-off during which a Polyvinyl alcohol (PVA) film is spin-coated and patterned, followed by the deposition or spin coating of the sensing layer and a second lift-off to pattern it on the IDEs area and form the final sensor. The process allows for upscaling when a single sensing layer is deposited and patterned in batch over the whole wafer or for the easy fabrication of chemical sensor arrays when depositing and precisely patterning different sensing layers on an array of IDEs. Showcasing the first approach, PHITA copolymer (a methacrylate tertrapolymer) is deposited and patterned over sensors with varying electrode gaps in order to fabricate simple humidity sensors, while in a following experiment, Poly(2-hydroxyethyl methacrylate) (PHEMA), Epoxy novolac resin (EPN), Poly(methyl methacrylate) (PMMA) and Poly(hydroxy styrene) PHS are patterned on the IDEs in order to form a sensor array. The different sensor configurations realized are evaluated when exposed to water, methanol and ethanol vapors with PHS sensor exhibiting a capacitance change of 44 fF (sensitivity: 1.87 fF / %RH), 7.4 fF and 4.6 fF at 10,000 ppm respectively. © 201

A miniature pressure system with a capacitive sensor and a passive telemetry link for use in implantable applications

Abstract-A miniature telemetric pressure-measuring system is presented in this paper. The system uses passive telemetry to transfer power to the transponder and pressure data to the remote base unit. Such telemetric systems are becoming ever more important in the biomedical field as the interest for in-vivo measurements of different biological parameters both of humans and animals is increasing. A novel capacitive-type pressure sensor based on an SiGeB diaphragm is used as a sensing element. The merits of combining a capacitive pressure sensor and passive telemetry lies in the inherent low-power consumption of the sensor and the continuous availability of power through induction. The pressure sensor is connected to an integrated interface circuit, which includes a capacitance to frequency converter and an internal voltage regulator to suppress supply voltage fluctuations on the transponder side. In addition, the sensor and accompanying interface circuit take up very little space so as to be suitable for implantation. [480] Index Terms-Blood-pressure measurements, passive telemetry, pressure sensors