USA as Represented by Secretary of the Navy

F Keith Perkins

Adam L Friedman

Paul M Campbell

Arthur W Snow

Mario Ancona

Aubrey T Hanbicki

James C Culbertson

Martin C Peckerar

David Kurt Gaskill

Rachael L Myers-Ward

Eric S Snow

Evgeniya H Lock

Lee James Johnson

John R Peele

Anindya Nath

Perry Skeath

William Bassett

Anthony K Boyd

R Andrew McGill

Berend T Jonker

Daniel J McCarthy

Eric J Houser

Glenn Jernigan

Enrique Cobas

Keir C Lauritzen

Stan V Stepnowski

Angela M Hodge-Miller

Christie R K Marrian

Optical and electronic detection of chemicals, and particularly strong electron-donors, by 2H to 1T phase-based transition metal dichalcogenide (TMD) films, detection apparatus incorporating the TMD films, methods for forming the detection apparatus, and detection systems and methods based on the TMD films are provided. The detection apparatus includes a 2H phase TMD film that transitions to the 1T phase under exposure to strong electron donors. After exposure, the phase state can be determined to assess whether all or a portion of the TMD has undergone a transition from the 2H phase to the 1T phase. Following detection, TMD films in the 1T phase can be converted back to the 2H phase, resulting in a reusable chemical sensor that is selective for strong electron donors.

2H to 1T phase based transition metal dichalcogenide sensor for optical and electronic detection of strong electron donor chemical vapors

A sensitive and selective, in-line method to measure and validate the sulfur content at ppb levels in both the liquid and gas phase of an analyte. The method includes patterning graphene, for example to form a mesa structure comprising horizontal or vertical lines or an array of multidentate star features; functionalizing the patterned graphene and attaching nanoparticles to the functionalized graphene to form a device; exposing the device to an analyte in the gas or liquid phase; detecting a change in electrical response when sulfur is present in the analyte; and recovering the device for future use. Also disclosed is the related sulfur detector.

Graphene-based PPB level sulfur detector

A sensitive and selective, in-line method to measure and validate the sulfur content at ppb levels in both the liquid and gas phase of fuel. The method includes etching graphene, for example to form a mesa structure comprising horizontal or vertical lines or an array of multidentate star features; functionalizing the etched graphene and attaching metal oxide nanoparticles to the functionalized graphene to form a device; exposing the device to a fuel in the gas or liquid phase; detecting a change in conductivity when sulfur is present in the fuel; and recovering the device for future use. Also disclosed is the related in-line graphene-based ppb level sulfur detector for fuels.

Graphene-based PPB level sulfur detector in fuels

An apparatus and method for producing chemielectric point-sensor systems with increased sensitivity and increased selectivity. The chemielectric sensor system includes a sensor/heater assembly, where the sensor is a chemielectric sensor whose resistance or capacitance changes upon exposure to chemical analytes. The heater functionality applies a programmed sequence of one or more thermal pulses to the sensor to quickly raise its temperature. After each thermal pulse ends the change in resistivity of the sensor is measured. Such data as a function of the pulse time and temperature are recorded and analyzed to determine the chemical composition (selectivity) and concentrations in the ambient vapor by comparison to a library dataset. The sensor operation with fast thermal pulses also allows operation at higher frequencies where the noise is lower and hence sensitivity is improved.

Thermally pulsed chemielectric point sensing

A method of making a low dimensional material chemical vapor sensor comprising providing a monolayer of a transition metal dichalcogenide, applying the monolayer to a substrate, applying a PMMA film, defining trenches, and placing the device in a n-butyl lithium (nbl) bath. A low dimensional material chemical vapor sensor comprising a monolayer of a transition metal dichalcogenide, the monolayer applied to a substrate, a region or regions of the transition metal dichalcogenide that have been treated with n-butyl lithium, the region or regions of the transition metal dichalcogenide that have been treated with n-butyl lithium have transitioned from a semiconducting to metallic phase, metal contacts on the region or regions of the transition metal dichalcogenide that have been treated with the n-butyl lithium.

2H/1T phase contact engineering for high performance transition metal dichalcogenide chemical vapor sensors

A molecular concentrator comprising a thermal ratchet for driving molecules from one place to another. A plurality of linear, two-dimensional, and/or three-dimensional arrangements of heater structures are arranged on or suspended above a substrate. Each of the heater structures is configured to strongly sorb a vapor of interest when the heater structure is at room temperature and to rapidly desorb the vapor when the heater structure is at an elevated temperature. The vapor sorption of the individual heater structures is made selective by surface treatments, by monomolecular film depositions or by thicker absorbent polymer depositions. By selectively heating and cooling the heater structures, vapor molecules incident on the heater structures can be directed in a desired manner, e.g., from heater structures closest to a vapor-containing environment to a sensor.

Molecular concentrator based on thermal ratcheting

A method of making a low-dimensional material chemical vapor sensor comprising exfoliating MoS, applying the monolayer flakes of MoSonto a SiO/Si wafer, applying a methylmethacrylate (MMA)/polymethylmethacrylate (PMMA) film, defining trenches for the deposition of metal contacts, and depositing one of Ti/Au, Au, and Pt in the trench and resulting in a MoSsensor. A low-dimensional material chemical vapor sensor comprising monolayer flakes of MoS, trenches in the SiO/Si wafer, metal contacts in the trenches, and thereby resulting in a MoSsensor. A full spectrum sensing suite comprising similarly fabricated parallel sensors made from a variety of low-dimensional materials including graphene, carbon nanotubes, MoS, BN, and the family of transition metal dichalcogenides. The sensing suites are small, robust, sensitive, low-power, inexpensive, and fast in their response to chemical vapor analytes.

Low-dimensional material chemical vapor sensors

A molecular concentrator comprising a thermal ratchet for driving molecules from one place to another. A plurality of conducting wires are arranged on or suspended above a substrate. Each of the wires is configured to strongly sorb a vapor of interest when the wire is at room temperature and to rapidly desorb the vapor when the wire is at an elevated temperature. By selectively heating and cooling the wires, vapor molecules incident on the wires can be directed in a desired manner, e.g., from the wires closest to the vapor-containing environment to a sensor.

A method of immersing an electrode in an electroplating solution while under vacuum, to substantially eliminate air and/or other gas from microscopic holes, cavities or indentations in the electrode. A method of electroplating an electrode in an electroplating solution including the application of a vacuum to the electrode while it is immersed in the electroplating solution to thereby substantially eliminate air and/or other gas from microscopic holes, cavities or indentations in the electrode. The electroplating liquid may be applied to only one side of the electrode ('the wet side') in which case, sufficient time is allowed to pass for the immersion liquid to fill the microscopic through-holes, cavities or indentations in the electrode. An enhancement of this mode is to force liquid through the microscopic holes from the wet side. A highly penetrating solvent may be used as an immersion liquid. Alternatively, carbon dioxide can be used as an immersion liquid, in which case the liquid carbon dioxide may be obtained by adjusting the temperature and pressure conditions in a closed container of gaseous carbon dioxide.

Preparing electrodes for electroplating

A sensing device having: a bottom electrode, a dielectric on the bottom electrode, a grid of nanoelectrodes on the dielectric, and a top electrode in electrical contact with the grid. A method of chemical or biological sensing comprising: providing a grid of nanoelectrodes; exposing the grid to fluid suspected of containing a chemical or biological analyte; and measuring a change in the capacitance and conductance of the grid.

Capacitive based sensing of molecular adsorbates on the surface of single wall nanotubes

An analog to digital converter includes a resistor-divider network including a plurality of resistors, an arbel channel circuit configured to generate a voltage sawtooth signal as an output, a dc-offset disposed to couple a node of the resistor-divider network and the arbel-channel circuit. The converter further includes a voltage reference circuit configured to generate a reference voltage, and a differential comparator configured to compare the voltage sawtooth signal with the reference voltage to produce a digital output signal corresponding to the voltage sawtooth signal. Method of converting an analog signal to a digital signal is also described.

Analog to digital converter using sawtooth voltage signals with differential comparator

A fiducial beam monitor includes a patterned diode layer on a semiconducting substrate. An electrical field between the diode (or diodes) on the diode layer and the semiconducting substrate modulates the size of the depletion layer formed by the diode or diode. A high energy beam incident upon a diode on the diode layer produces a greater current than a high energy beam incident upon a non-diodic region of the same layer. In use, the beam monitor is typically fixed to the backside of a workpiece such as a semitransparent membrane being patterned by a focused high energy beam that is translated with respect to workpiece and attached monitor. The changes in current during translation are then correlated with the position of the beam with respect to the pattern on the diode layer.

Growing community of inventors

Alexandria, VA, United States of America

F Keith Perkins