High‐Gain Double‐Bulk Mixer in 65 nm CMOS with 830 pW Power Consumption

A low‐power down‐sampling mixer in a low‐power digital 65 nm CMOS technology is presented. The mixer consumes only 830 µW at 1.2 V supply voltage by combining an NMOS and a PMOS mixer with cascade transistors at the output. The measured gain is (19 °1 dB) at frequencies between 100 MHz and 3 GHz. An IIP3 of ?5.9 dBm is achieved.     

Polydimethylsiloxane permeability-based method for the continuous and specific detection of hydrogen sulfide

Hydrogen sulfide (H(2)S) is known to play a physiological role in processes as diverse as vasodilation, maintenance of vascular tone, neurotransmission, and immune response. The multitude of physiological functions in which H(2)S is involved warrants the development of useful methods for its detection. Here, we introduce a simple and continuous H(2)S detection method that exploits the relatively high polydimethylsiloxane (PDMS) permeability of H(2)S in comparison to other thiols typically encountered in the cellular milieu. In this method, 96-well inserts constructed of PDMS act as an H(2)S-permeable membrane, eliminating nonspecific thiol detection. This design also makes it possible to use virtually any available thiol-specific probe such as Ellman's reagent which was used here to detect H(2)S once it crossed the PDMS membrane. Utilizing this method, a detection limit of 9.2 ± 1.9 ppb(m) (parts per billion (by mole) or ~0.51 μM in 1.6 mL of buffer) free H(2)S (detected as solution sulfide) was achieved. In addition, the assay was used to determine K(M) and V(max) for natural substrates of cystathionine γ-lyase (CSE), the main enzyme responsible for H(2)S production in peripheral tissues. The K(M) and V(max) of CSE for cysteine were 3.79 ± 2.07 mM and 0.37 ± 0.02 nmol H(2)S/min, respectively. K(M) and V(max) for homocysteine were 6.90 ± 1.78 mM and 1.10 ± 0.19 nmol H(2)S/min, respectively. In addition, the assay was used to examine the potential for a direct interaction of H(2)S and NO. The levels of detected H(2)S decreased in the presence of NO under normoxia but not under anoxia indicating that H(2)S does not react with NO but with N(2)O(3) likely formed in the hydrophobic environment of PDMS.     

High accuracy alignment facility for the receiver and transmitter of the BepiColombo Laser Altimeter

The accurate co-alignment of the transmitter to the receiver of the BepiColombo Laser Altimeter is a challenging task for which an original alignment concept had to be developed. We present here the design, construction and testing of a large collimator facility built to fulfill the tight alignment requirements. We describe in detail the solution found to attenuate the high energy of the instrument laser transmitter by an original beam splitting pentaprism group. We list the different steps of the calibration of the alignment facility and estimate the errors made at each of these steps. We finally prove that the current facility is ready for the alignment of the flight instrument. Its angular accuracy is 23 μrad.     

Experimental study of density segregation at end walls in a horizontal rotating cylinder saturated with fluid: friction to lubrication transition

What is the effect of interstitial fluid viscosity on granular density segregation in a horizontal rotating cylinder? We conducted experiments in the rolling regime with equal amounts of equal sized high and low density, nearly spherical granular particles saturated with air, water, and water-glycerin mixtures. We held particle density, rotation rate and characteristic length scale constant to highlight differences due purely to the interstitial fluid. Images of the granular flow at an end wall were used to determine radial and axial density segregation rates and patterns. Over a four decade change in viscosity, segregation rates varied by only a factor of two. However, for ratios of lubrication to frictional stresses above one, segregation rates decreased by about 30%, and we observed several notable phenomena in the segregation pattern formation. These were a creeping mode of radial density segregation, a change in shape of the granular bed to kidney shaped from flat, and for cylinders more than half full the typically reported unsheared central portion of the granular bed (often referred to in the literature as a core region) was disrupted by a wavy instability where the rate of disappearance of the core region decreased as the fill level increased.     

Hysteresis errors of commonly used sensor materials

In this study, the hysteresis errors of 17-4 PH precipitation hardened stainless steel, aged Cu–Be (copper beryllium) alloy and AISI 4340 steel, which are commonly used as spring materials for sensors, were determined. Various heat treatment processes were applied to the samples of sensor materials in order to decrease the hysteresis error. The effect of the microstructure on the hysteresis error was also investigated. According to the results, the hysteresis errors were increased 2–3 times for higher annealing temperatures or holding time after solutionized. The results showed that the hysteresis characteristics can be improved by the application of suitable thermo-mechanical treatment processes. Microstructural changes can effect the sensor behavior and increase or decrease measurement errors. The lowest hysteresis errors were obtained in short-term aged for Cu–Be material and fine martensite for AISI 4340 steel and short-term aged for 17-4 PH steel.     

Streamflow Properties from Time Series of Surface Velocity and Stage

Time series of surface velocity and stage have been collected simultaneously. Surface velocity was measured using an array of newly developed continuous-wave microwave sensors. Stage was obtained from the standard U.S. Geological Survey (USGS) measurements. The depth of the river was measured several times during our experiments using sounding weights. The data clearly showed that the point of zero flow was not the bottom at the measurement site, indicating that a downstream control exists. Fathometer measurements confirmed this finding. A model of the surface velocity expected at a site having a downstream control was developed. The model showed that the standard form for the friction velocity does not apply to sites where a downstream control exists. This model fit our measured surface velocity versus stage plots very well with reasonable values of the parameters. Discharges computed using the surface velocities and measured depths matched the USGS rating curve for the site. Values of depth-weighted mean velocities derived from our data did not agree with those expected from Manning’s equation due to the downstream control. These results suggest that if real-time surface velocities were available at a gauging station, unstable stream beds could be monitored.     

Thin-film devices fabricated with benzocyclobutene adhesive wafer bonding

In this paper, we present and elaborate on die to wafer bonding technology with benzocyclobutene (BCB). This technology allows to fabricate a variety of reliable waferbonded components in a fairly simple way using only standard cleanroom equipment. We demonstrate the fabrication of passive devices such as microring resonators, as well as active components such as lasers and LEDs. We show good performance of these devices by presenting measurements of their characteristics. Furthermore, these devices were subjected to damp-heat testing, demonstrating the good quality of the BCB-bonding procedure. Finally, due to the low thermal conductivity of BCB, thermal management needs some attention. We present an analysis of the thermal problem and suggest a possible solution.