Pyrolyzed-parylene based sensors and method of manufacture

A method (and resulting structure) for fabricating a sensing device. The method includes providing a substrate comprising a surface region and forming an insulating material overlying the surface region. The method also includes forming a film of carbon based material overlying the insulating material and treating to the film of carbon based material to pyrolyzed the carbon based material to cause formation of a film of substantially carbon based material having a resistivity ranging within a predetermined range. The method also provides at least a portion of the pyrolyzed carbon based material in a sensor application and uses the portion of the pyrolyzed carbon based material in the sensing application. In a specific embodiment, the sensing application is selected from chemical, humidity, piezoelectric, radiation, mechanical strain or temperature

Pyrolyzed thin film carbon

A method of making carbon thin films comprises depositing a catalyst on a substrate, depositing a hydrocarbon in contact with the catalyst and pyrolyzing the hydrocarbon. A method of controlling a carbon thin film density comprises etching a cavity into a substrate, depositing a hydrocarbon into the cavity, and pyrolyzing the hydrocarbon while in the cavity to form a carbon thin film. Controlling a carbon thin film density is achieved by changing the volume of the cavity. Methods of making carbon containing patterned structures are also provided. Carbon thin films and carbon containing patterned structures can be used in NEMS, MEMS, liquid chromatography, and sensor devices

Photodefinable silicone MEMS gaskets and O-rings for microfluidics packaging

Fully-integrated MEMS gaskets and O-rings made of SU8 and photosensitive silicone are described and tested under varying conditions of compressive stress. An analytical theory of microgasket sealing behavior is also presented. The theory shows the critical importance of device surface flatness. The microgasket is found to be capable of deforming approximately 25% of its initial thickness and forming leak-free fluidic seals at inlet pressures below 50 psi. The microgasket is incorporated into a modular microfluidic system that exhibits system leak rates lower than 2.3 nL/min for working pressures up to 250 psi. Fabricated chip-to-chip interconnects exhibit a low dead volume of approximately 9 nL while further optimization can reduce dead volume per interconnect to about 1 nL

Electrochemical characterization of parylene-embedded carbon nanotube nanoelectrode arrays

A novel parylene-embedded carbon nanotube nanoelectrode array is presented for use as an electrochemical detector working electrode material. The fabrication process is compatible with standard microfluidic and other MEMS processing without requiring chemical mechanical polishing. Electrochemical studies of the nanoelectrodes showed that they perform comparably to platinum. Electrochemical pretreatment for short periods of time was found to further improve performance as measured by cathodic and anodic peak separation of K3Fe(CN)6. A lower detection limit below 0.1 µM was measured and with further fabrication improvements detection limits between 100 pM and 10 nM are possible. This makes the nanoelectrode arrays particularly suitable for trace electrochemical analysis

The Effects of Replacing Native Forest on the Quantity and Impacts of In-Channel Pieces of Large Wood in Chilean Streams

Dead trees in rivers can significantly affect their morphological and ecological properties by increasing flow resistance, affecting sediment transport, and storing organic matter. Logs are usually recruited from banks or along the entire upstream basin. Although it is generally acknowledged that forested headwater streams feature higher volumes of in-channel pieces of large wood, the influence of forest type and forest management of the potential recruitment zone on the volumes and effects of wood have been less explored, especially in relation to the effects of replacing native forests with pine plantations. This paper presents a comparison of volumes of wood, and characteristics and effects on streams draining paired basins with comparable slopes, areas, and hydrologic regimes, but different in terms of land use. The five selected pairs of basins are located in the Coastal and Andean mountain Ranges in central Chile, in order to compare native forest and pine plantation basins. The results show that logs tend to be shorter and with larger diameters in streams draining native forest basins. Because of their smaller dimensions, logs and jams tend to be more mobile and oriented parallel to the flow. Volumes of in-channel wood in native forest basins are only slightly larger than in pine plantation basins, and no differences have been identified in terms of morphological effects on channel geometry. Also, fish type and biomass were comparable among pairs. Evidence highlights the importance of the width of riparian buffers in mitigating the effects of land use change, especially the substitution of native forest with plantations

A Modular Microfluidic Approach to Nano High-Performance Liquid Chromatography with Electrochemical Detection

The field of microfluidics faces many challenges that must be overcome before wide-spread use of microfluidic devices can be achieved. Chief among these challenges are the need for reliable, user-friendly packaging and robust, reconfigurable, and reusable microfluidic systems. A modular microfluidic design approach to microfluidic systems is developed and a prototype modular nano high-performance liquid chromatography (nHPLC) system with electrochemical detection is demonstrated. The modular microfluidic system requires high operating pressure, low dead volume interconnects, and assembly into a simple, reliable package. The modular approach differs from the classic monolithic approach to microfluidic systems by offering increased system flexibility, reduced individual device fabrication complexity, and increased independence of component fabrication technologies at the cost of an additional microfluidic interconnect component. Microgaskets and MEMS O-rings based on a new, commercial, photodefinable silicone are developed and characterized to provide the necessary low dead volume interconnects. The microgaskets and MEMS O-rings are shown to work well at typical operating pressures and did not leak under operating pressures up to 250 psi. The modular nHPLC system is used to separate a nitrate/nitrite sample with efficiencies favorably comparable to commercial macro HPLC systems and other nano HPLC systems reported in the literature. Finally, new electrochemical working electrode materials are presented for use in electrochemical detectors. One material is a thin-film carbon based on pyrolyzed Parylene-C that can conformally coat high-aspect-ratio structures to achieve better than a ten-fold increase in effective electrode area relative to geometric surface area. The second material is a carbon nanotube (CNT) nanoarray that uses a Parylene-C stabilization and insulation matrix. The CNT nanoarray shows a bifurcated sensitivity profile that indicates possible application to trace analyte detection. The combination of trace analyte detection and high-efficiency analyte separation in modular microfluidic systems places applications, such as near real-time, single cell small molecule secretion monitoring, within reach.</p

Modular microfluidic interconnects using photodefinable silicone microgaskets and MEMS O-rings

Fully-integrated microgaskets and MEMS o-rings made of SU8 and photosensitive silicone are described and tested under varying conditions of compressive stress. An analytical theory of microgasket sealing behavior is also presented. The theory shows the critical importance of device surface flatness. The microgasket is found to be capable of deforming approximately 25% of its initial thickness and forming leakfree fluidic seals at inlet pressures below 50 psi. The microgasket is incorporated into a modular microfluidic system that exhibits system leak rates lower than 2.3 nL/min for working pressures up to 250 psi. The microgaskets and O-rings prove reusable under practical operating conditions. Fabricated chip-to-chip interconnects exhibit a low dead volume of approximately 9 nL while further optimization reduced the dead volume per interconnect to about 1 nL

Configurable IP-space maps for large-scale, multi-source network data visual analysis and correlation

The need to scale visualization of cyber (IP-space) data sets and analytic results as well as to support a variety of data sources and missions have proved challenging requirements for the development of a cyber common operating picture. Typical methods of visualizing IP-space data require unreliable domain conversions such as IP geolocation, network topology that is difficult to discover, or data sets that can only display one at a time. In this work, we introduce a generalized version of hierarchical network maps called configurable IP-space maps that can simultaneously visualize multiple layers of IP-based data at global scale. IP-space maps allow users to interactively explore the cyber domain from multiple perspectives. A web-based implementation of the concept is described, highlighting a novel repurposing of existing geospatial mapping tools for the cyber domain. Benefits of the configurable IP-space map concept to cyber data set analysis using spatial statistics are discussed. IP-space map structure is found to have a strong effect on data clustering behavior, hinting at the ability to automatically determine concentrations of network events within an organizational hierarchy