Development of a low actuation voltage RF MEMS switch

This paper reports on the design of a novel ultra low actuation voltage, low loss radio frequency micro-electro-mechanical system (RF MEMS) capacitive shunt switch. The concept of the switch relies on a mechanically unconstrained armature actuated over a coplanar waveguide using electrostatic forces. The minimum actuation voltage of the switch is <2V, with an isolation of 40dB and insertion loss <0.7dB at 78GHz

Search for flavor-changing neutral currents and lepton-family-number violation in two-body D0 decays

Results of a search for the three neutral charm decays, D0 -> mu e, D0 -> mu mu, and D0 -> e e, are presented. This study was based on data collected in Experiment 789 at the Fermi National Accelerator Laboratory using 800 GeV/c proton-Au and proton-Be interactions. No evidence is found for any of the decays. Upper limits on the branching ratios, at the 90% confidence level, are obtained.Comment: 28 pages, 18 figures. Submitted to Physical Review

A novel low cost spring-less RF MEMS switch prototype

This work reports on the fabrication process and measurements of a novel radio frequency microelectromechanical system (RF MEMS) capacitive shunt switch prototype with a mechanically unconstrained armature. The prototype is fabricated in a low cost process based on a printed circuit board (PCB) bonded to a glass slide. The minimum actuation voltage (Vact) of the prototype is 93 V, with a switching time taken from the down to up state (Trise) and from the up to down state (Tfall) of 105 ms and 26 ms respectively

Design and simulation of a spring-less micro switch

This paper reports on the design of an ultra low actuation voltage microelectromechanical systems (MEMS) switch. The mechanical design of the spring-less switch is presented. The theoretical actuation voltage of the switch is shown to be as low as 0.34 V. The concept is tested using an electrostatic levitated disc accelerometer, reconfigured to operate as a MEMS switch. Experimental and theoretical data for the dynamic behaviour of these devices are also presented. The results of this paper validate the feasibility of realising ultra low-voltage MEMS switches using electrostatic levitation. Key words: Low actuation voltage, microelectromechanical systems (MEMS) switches, electrostatic actuation, no mechanical spring

Determination of specific contact resistance of Ge₂Sb₂Te₅ phase change materials by spacer etched nanowires

Phase change materials (PCM) based memory device is considered as one of the most promising candidates for next-generation non-volatile solid-state memory [1]. The set and reset states in this device correspond to a low resistance and a high resistance of the cell, which in-turn correspond to the crystalline and amorphous states of the phase change material, respectively. The total resistance of a phase change memory cell, however, consists of the resistance from the PCM and the interfacial contact resistance of the PCM to the electrodes. Although a large amount research has been done on characterization of PCM resistance, little attention is paid to study the contact resistance. Here in this work, the contact resistance of Ge2Sb2Te5 to titanium nitride (TiN) electrode has been characterized in both set and reset states using a nanowire structure obtained from spacer etch. This spacer etch is a novel technique and can be used as a low-cost alternative to E-beam lithography for sub-hundred nanometre nanowire fabrication. Unlike bottom-up technology, it is compatible with current CMOS process and the geometry and location of the nanowires can be precisely controlled. In this case it allows us make long structures with small contact area to separate the resistive contribution of bulk and interfac

Contact resistance measurement of Ge₂Sb₂Te₅ phase change material to TiN electrode by spacer etched nanowire

Ge2Sb2Te5 (GST) phase change nanowires have been fabricated using a top-down spacer etch process. This approach enables controls over the dimension and location of the nanowires without affecting the electrical properties. Phase change devices based on these nanowires have been used to systematically investigate the contact resistance between GST phase change material and TiN metal electrodes. The specific contact resistance was found to be 7.96 × 10−5 Ω cm2 for crystalline GST and 6.39 × 10−2 Ω cm2 for amorphous GST. The results suggest that contact resistance plays a dominant role in the total resistance of GST memory device in both crystalline and amorphous states

Removal of dental biofilms with an ultrasonically-activated water stream

Acidogenic bacteria within dental plaque biofilms are the causative agents of caries. Consequently, maintenance of a healthy oral environment with efficient biofilm removal strategies is important to limit caries, as well as halt progression to gingivitis and periodontitis. Recently, a novel cleaning device has been described using an ultrasonically activated stream (UAS) to generate a cavitation cloud of bubbles in a freely flowing water stream that has demonstrated the capacity to be effective at biofilm removal. In this study, UAS was evaluated for its ability to remove biofilms of the cariogenic pathogen Streptococcus mutans UA159, as well as Actinomyces naeslundii ATCC 12104 and Streptococcus oralis ATCC 9811, grown on machine-etched glass slides to generate a reproducible complex surface and artificial teeth from a typodont training model. Biofilm removal was assessed both visually and microscopically using high-speed videography, confocal scanning laser microscopy (CSLM), and scanning electron microscopy (SEM). Analysis by CSLM demonstrated a statistically significant 99.9% removal of S. mutans biofilms exposed to the UAS for 10 s, relative to both untreated control biofilms and biofilms exposed to the water stream alone without ultrasonic activation (P < 0.05). The water stream alone showed no statistically significant difference in removal compared with the untreated control (P = 0.24). High-speed videography demonstrated a rapid rate (151 mm2 in 1 s) of biofilm removal. The UAS was also highly effective at S. mutans, A. naeslundii, and S. oralis biofilm removal from machine-etched glass and S. mutans from typodont surfaces with complex topography. Consequently, UAS technology represents a potentially effective method for biofilm removal and improved oral hygiene

Reconfigurable phase-change photomask for grayscale photolithography

We demonstrate a grayscale photolithography technique which uses a thin phase-change film as a photomask to locally control the exposure dose and allows three-dimensional (3D) sculpting photoresist for the manufacture of 3D structures. Unlike traditional photomasks, the transmission of the phase-change material photomask can be set to an arbitrary gray level with submicron lateral resolution, and the mask pattern can be optically reconfigured on demand, by inducing a refractive-index-changing phase-transition with femtosecond laser pulses. We show a spiral phase plate and a phase-type super-oscillatory lens fabricated on Si wafers to demonstrate the range of applications that can be addressed with this technique