An inkjet-printed chemical fuse

Inkjet printing of the conductive polymer poly(3,4-ethylene dioxythiophene) doped with polystyrene sulfonated acid has been used as the basis for a sensor for organic vapors. The electrical resistance of the film was monitored as it was exposed to atmospheres containing alcohol. Ultrathin films exhibited a sharp and nonreversible increase in their resistance. This resulted from a change in the morphology of the organic layer, thereby disrupting the current flow through the polymer. An intended application for these inkjet-printed devices is in disposable handheld instruments to monitor the presence of organic vapors above a threshold level

Transport mechanisms in porous silicon

The current transport mechanism through porous silicon (PS) films fabricated from 8 to 12 Omega cm p-type silicon (p-Si) substrates has been investigated using current-voltage I(V) measurements on metal/PS/p-Si/metal devices in the temperature range of 77-300 K. The characteristics for all devices show a rectifying behavior with ideality factor very close to unity. A value of 0.7 eV is obtained for the barrier height at the interface between PS and bulk p-Si at room temperature and the barrier height is found to increase with rising temperature. A band model is proposed in order to explain the observed characteristics. (C) 1998 American Institute of Physics

Electrical Characteristics of Hybrid-Organic Memory Devices Based on Au Nanoparticles

We report on the fabrication and characterization of hybrid-organic memory devices based on gold (Au) nanoparticles that utilize metal–insulator–semiconductor structure. Au nanoparticles were produced by sputtering and inert-gas condensation inside an ultrahigh-vacuum compatible system. The nanoparticles were self-assembled on a silicon dioxide (SiO2)/silicon (Si) substrate, then coated with a poly(methyl methacrylate) (PMMA) insulating layer. Aluminum (Al) electrodes were deposited by thermal evaporation on the Si substrate and the PMMA layer to create a capacitor. The nanoparticles worked as charge storage elements, while the PMMA is the capacitor insulator. The capacitance–voltage (C–V) characteristics of the fabricated devices showed a clockwise hysteresis with a memory window of 3.4 V, indicative of electron injection from the top Al electrode through the PMMA layer into Au nanoparticles. Charge retention was measured at the stress voltage, demonstrating that the devices retain 94% of the charge stored after 3 h of continuous testing

Quantitative distribution of a panel of circulating mRNA in preeclampsia versus controls.

OBJECTIVE: The aim of this study was to evaluate whether the quantitative distribution of a panel of circulating mRNAs from maternal whole blood of normal pregnancies is statistically different from those complicated with preeclampsia (PE) with or without intrauterine growth restriction (IUGR). METHODS: Maternal whole blood of six subjects with mild or severe PE with or without IUGR and 30 matched controls (1:5 match for gestational age) were retrospectively examined for circulating mRNA markers. Seven specific mRNA markers were identified and chosen based on previous microarray mRNA expressions performed on placental tissue from normal and PE patients. They were human placental lactogen (hPL), inhibin A, KISS-1, pregnancy-associated plasma protein-A (PAPP-A), plasminogen activator inhibitor type 1 (PAI-1), selectin-P and vascular endothelial growth factor receptor (VEGFR), which were therefore quantified for statistical purposes. RESULTS: Median gestational age was 229 (178-283) and 232 (194-262) days for controls and cases respectively. All mRNA markers but PAPP-A, showed statistically different median values. They were hPL, inhibin A, KISS-1, PAI-1, Selectin-P, and VEGFR. Inhibin A, Selectin-P and VEGFR showed higher values than expected for controls. Instead, hPL, KISS-1 and PAI-1 values of PE patients were lower than those of controls. Selectin-P was the marker with the most aberrant difference, followed by VEGFR and KISS-1. CONCLUSION: This preliminary analysis revealed that the median values of a panel of mRNAs from the maternal blood of PE patients were different from those of the same gestational age control group at the third trimester. If prospective studies at the second trimester could detect a related marker sufficiently able to discriminate between affected and unaffected patients and thus detect the disease before its clinical onset, then a screening project using a panel of mRNAs would be feasible

Pentacene-based metal-insulator-semiconductor memory structures utilizing single walled carbon nanotubes as a nanofloating gate

A pentacene-based organic metal-insulator-semiconductor memory device, utilizing single walled carbon nanotubes (SWCNTs) for charge storage is reported. SWCNTs were embedded, between SU8 and polymethylmethacrylate to achieve an efficient encapsulation. The devices exhibit capacitance-voltage clockwise hysteresis with a 6 V memory window at ± 30 V sweep voltage, attributed to charging and discharging of SWCNTs. As the applied gate voltage exceeds the SU8 breakdown voltage, charge leakage is induced in SU8 to allow more charges to be stored in the SWCNT nodes. The devices exhibited high storage density (∼9.15 × 1011 cm−2) and demonstrated 94% charge retention due to the superior encapsulation