Vladimir Ermolov

Design of a temperature-stable RF MEM capacitor

This paper presents a novel temperature-compensated two-state microelectromechanical (MEM) capacitor. The principle to minimize temperature dependence is based on geometrical compensation and can be extended to other devices such as MEM varactors. The compensation structure eliminates the effect of intrinsic and thermal stress on device operation. This leads to a temperature-stable device without compromising the quality factor (Q) or the voltage behavior. The compensation structure increases the robustness of the devices, but does not require any modifications to the process. Measurement results verify that the OFF and ON capacitance change is less than 6% and the pull-in voltage is less than 5% when the temperature is varied from -30 to +70/spl deg/C.

Microelectromechanical capacitors for RF applications

This paper describes the design principles of electrostatically actuated microelectromechanical capacitors. Key properties, such as capacitance tuning range, quality factor (Q), different control methods, thermal stability, effect of radio frequency signal on capacitance and gas damping are examined. Experimental devices were designed and fabricated using the design principles. The two-gap capacitor has a measured nominal capacitance of 1.58 pF and achieves a tuning range of 2.25:1 with parasitics. When all parasitic capacitances to the substrate are extracted the measured nominal capacitance is 1.15 pF and the tuning range is 2.71:1. The device is made of electroplated gold and has a Q of 66 at 1 GHz, and 53 at 2 GHz. In addition, two- and three-state capacitors were designed, fabricated and characterized.

Carbon nanotube thin film transistors based on aerosol methods

We demonstrate a fabrication method for high-performance field-effect transistors (FETs) based on dry-processed random single-walled carbon nanotube networks (CNTNs) deposited at room temperature. This method is an advantageous alternative to solution-processed and direct CVD grown CNTN FETs, which allows using various substrate materials, including heat-intolerant plastic substrates, and enables an efficient, density-controlled, scalable deposition of as-produced single-walled CNTNs on the substrate directly from the aerosol (floating catalyst) synthesis reactor. Two types of thin film transistor (TFT) structures were fabricated to evaluate the FET performance of dry-processed CNTNs: bottom-gate transistors on Si/SiO2 substrates and top-gate transistors on polymer substrates. Devices exhibited on/off ratios up to 10(5) and field-effect mobilities up to 4 cm(2) V(-1) s(-1). The suppression of hysteresis in the bottom-gate device transfer characteristics by means of thermal treatment in vacuum and passivation by an atomic layer deposited Al(2)O(3) film was investigated. A 32 nm thick Al(2)O(3) layer was found to be able to eliminate the hysteresis.

Significance of Nanotechnology for Future Wireless Devices and Communications

This paper reviews the expected wide and profound impact of nanotechnology for future wireless devices and communication technologies.

Microreplicated RF toroidal inductor

This paper reports on the modeling and fabrication of a truly three-dimensional high-quality-factor toroidal inductor using polymer replication processes. The critical dimensions are in the micrometer range, and the applied manufacturing method is based on polymer replication. Electrical measurements show that the inductor with an inductance of 6.0 nH exhibits a peak quality factor of 50 at a frequency of 3 GHz. Model verified by the measurement results shows that further improvement is still possible. Furthermore, the applied manufacturing technique can be extended to become a flexible packaging platform.

Single-walled carbon nanotube networks for ethanol vapor sensing applications

AbstractNetworks of pristine high quality single walled carbon nanotubes (SWNTs), the SWNTs after Ar-plasma treatment (from 2 to 12 min) and carbon nanobuds (CNBs) have been tested for ethanol vapor sensing. It was found that the pristine high quality SWNTs do not exhibit any ethanol sensitivity, while the introduction of defects in the tubes results in the appearance of the ethanol sensitivity. The CNB network showed ethanol sensitivity without plasma treatment. Both CNB and low defect (after 3 min treatment) SWNT networks exhibit significant drift in the resistance baseline, while heavily plasma-treated (9 min) SWNTs exhibited high ethanol vapor sensitivity without the baseline change. The mechanisms of the ethanol sensitivity and stability after the plasma irradiation are attributed to the formation of sensitive dangling bonds in the SWNTs and formation of defect channels facilitating access of the ethanol vapor to all parts of the bundled nanotubes.

Health Care Applications Based on Mobile Phone Centric Smart Sensor Network

This paper presents the MIMOSA architecture and development platform to create Ambient Intelligence applications. MIMOSA achieves this objective by developing a personal mobile-device centric architecture and open technology platform where microsystem technology is the key enabling technology for their realization due to its low-cost, low power consumption, and small size. This paper focuses the demonstration activities carried out in the field of health care. MIMOSA project is a European level initiative involving 15 enterprises and research institutions and universities.

Lithography-free fabrication of carbon nanotube network transistors

A novel non-lithographic technique for the fabrication of carbon nanotube thin film transistors is presented. The whole transistor fabrication process requires only one mask which is used both to pattern transistor channels based on aerosol synthesized carbon nanotubes and to deposit electrodes by metal evaporation at different angles. An important effect of electrodynamic focusing was utilized for the directed assembly of transistor channels with feature sizes smaller than the mask openings. This dry non-lithographic method opens up new avenues for device fabrication especially for low cost flexible and transparent electronics.

Identifying User Requirements for a Mobile Terminal Centric Ubiquitous Computing Architecture

System level solutions affect many properties of ubiquitous applications and thus also user experience. That is why user point of view should guide the design of mobile architectures although the users will see them indirectly, via the applications. This paper describes our approach in identifying user requirements for a ubiquitous computing architecture that facilitates mobile applications sensing their environment. The sensing is based on wireless connectivity to tags and sensors in the environment. We illustrated a representative set of future applications as scenarios and proof of concepts and evaluated them with potential users. Scenarios were analyzed to identify generic use cases and to understand the implications of the user feedback on the architecture. Our experiences show that user requirements for system level solutions can be identified with this approach. We identified several requirements for the architecture dealing with user interaction, wireless measurements, context-awareness, taking applications into use and ethical issues

Gas damping model for a RF MEM switch and its dynamic characteristics

A compact model for a capacitive RF MEM switch with damping is presented. The damping model is based on analytic expressions for flow resistances due to the rarefied air flow in the gap and in the perforation holes. The complete switch model is constructed of elements resulting from the discretization of the beam deflection equation and has been implemented as a nonlinear electrical equivalent circuit. The model reproduces the beam displacement accurately. Comparison with measured transient on/off capacitance characteristics shows very good agreement.