Brent L. Haroldsen

Development of an integrated microfluidic instrument for unattended water-monitoring applications.

Field‐deployable detection technologies in the nations water supplies have become a high priority in recent years. The unattended water sensor is presented which employs microfluidic chip‐based gel electrophoresis for monitoring proteinaceous analytes in a small integrated sensor platform. The instrument collects samples directly from a domestic water flow. The sample is then processed in an automated microfluidic module using in‐house designed fittings, microfluidic pumps and valves prior to analysis via Sandias μChemLab™ module, which couples chip‐based electrophoresis separations with sensitive LIF detection. The system is controlled using LabVIEW software to analyze water samples about every 12 min. The sample preparation, detection and data analysis has all been fully automated. Pressure transducers and a positive control verify correct operation of the system, remotely. A two‐color LIF detector with internal standards allows corrections to migration time to account for ambient temperature changes. The initial unattended water sensor prototype is configured to detect protein biotoxins such as ricin as a first step toward a total bioanalysis capability based on protein profiling. The system has undergone significant testing at two water utilities. The design and optimization of the sample preparation train is presented with results from both laboratory and field testing.

On-line monitoring system for chemical warfare agents using automated capillary micellar electrokinetic chromatography

We present an automated analysis system for the detection of the chemical warfare blister agents, sulfur mustard (HD) and lewisite (L), in aqueous samples without any chemical derivatization. The system is compact in size and designed to operate in the field in a safe, autonomous manner for near real-time monitoring applications. It uses anionic surfactant-based capillary micellar electrokinetic chromatography (MEKC) to separate the sample followed by UV detection. The analysis time is sufficiently fast to allow direct detection of HD which enabled the estimation of effective hydrolysis rates in the aqueous sample matrix. The estimated hydrolysis half-life of HD in our system was 4.85 ± 0.05 min. The detection limit of HD was determined to be 10 ppm with a signal to noise ratio of 5. By contrast, L hydrolyzed too rapidly in aqueous samples to enable direct detection. Instead the first hydrolysis product 2-chlorovinyl arsonous acid (CVAA), also considered a blister agent, was detected with a detection limit of 0.7 ppm with a signal to noise ratio of 5.

Life assessment of full-scale EDS vessel under impulsive loadings.

The Explosive Destruction System (EDS) was developed by Sandia National Laboratories for the US Army Product Manager for Non-Stockpile Chemical Materiel (PMNSCM) to destroy recovered, explosively configured, chemical munitions. PMNSCM currently has five EDS units that have processed over 1,400 items. The system uses linear and conical shaped charges to open munitions and attack the burster followed by chemical treatment of the agent. The main component of the EDS is a stainless steel, cylindrical vessel, which contains the explosion and the subsequent chemical treatment. Extensive modeling and testing have been used to design and qualify the vessel for different applications and conditions. The high explosive (HE) pressure histories and subsequent vessel response (strain histories) are modeled using the analysis codes CTH and LS-DYNA, respectively. Using the model results, a load rating for the EDS is determined based on design guidance provided in the ASME Code, Sect. VIII, Div. 3, Code Case No. 2564. One of the goals is to assess and understand the vessel’s capacity in containing a wide variety of detonation sequences at various load levels. Of particular interest are to know the total number of detonation events at the rated load that can be processed inside each vessel, and a maximum load (such as that arising from an upset condition) that can be contained without causing catastrophic failure of the vessel. This paper will discuss application of Code Case 2564 to the stainless steel EDS vessels, including a fatigue analysis using a J-R curve, vessel response to extreme upset loads, and the effects of strain hardening from successive events.Copyright

Design and fabrication of a meso-scale stirling engine and combustor.

Power sources capable of supplying tens of watts are needed for a wide variety of applications including portable electronics, sensors, micro aerial vehicles, and mini-robotics systems. The utility of these devices is often limited by the energy and power density capabilities of batteries. A small combustion engine using liquid hydrocarbon fuel could potentially increase both power and energy density by an order of magnitude or more. This report describes initial development work on a meso-scale external combustion engine based on the Stirling cycle. Although other engine designs perform better at macro-scales, we believe the Stirling engine cycle is better suited to small-scale applications. The ideal Stirling cycle requires efficient heat transfer. Consequently, unlike other thermodynamic cycles, the high heat transfer rates that are inherent with miniature devices are an advantage for the Stirling cycle. Furthermore, since the Stirling engine uses external combustion, the combustor and engine can be scaled and optimized semi-independently. Continuous combustion minimizes issues with flame initiation and propagation. It also allows consideration of a variety of techniques to promote combustion that would be difficult in a miniature internal combustion engine. The project included design and fabrication of both the engine and the combustor. Two engine designs were developed. The first used a cylindrical piston design fabricated with conventional machining processes. The second design, based on the Wankel rotor geometry, was fabricated by through-mold electroforming of nickel in SU8 and LIGA micromolds. These technologies provided the requisite precision and tight tolerances needed for efficient micro-engine operation. Electroformed nickel is ideal for micro-engine applications because of its high strength and ductility. A rotary geometry was chosen because its planar geometry was more compatible with the fabrication process. SU8 lithography provided rapid prototypes to verify the design. A final high precision engine was created via LIGA. The micro-combustor was based on an excess enthalpy concept. Development of a micro-combustor included both modeling and experiments. We developed a suite of simulation tools both in support of the design of the prototype combustors, and to investigate more fundamental aspects of combustion at small scales. Issues of heat management and integration with the micro-scale Stirling engine were pursued using CFD simulations. We found that by choice of the operating conditions and channel dimensions energy conversion occurs by catalysis-dominated or catalysis-then-homogeneous phase combustion. The purpose of the experimental effort in micro-combustion was to study the feasibility and explore the design parameters of excess enthalpy combustors. The efforts were guided by the necessity for a practical device that could be implemented in a miniature power generator, or as a stand-alone device used for heat generation. Several devices were fabricated and successfully tested using methane as the fuel.

EDS Containment Vessel Explosive Test and Analysis

This report documents the results of two of tests that were performed on an explosive containment vessel at Sandia National Laboratories in Albuquerque, New Mexico in July 2013 to provide some deeper understanding of the effects of charge geometry on the vessel response [1]. The vessel was fabricated under Code Case 2564 of the ASME Boiler and Pressure Vessel Code, which provides rules for the design of impulsively loaded vessels [2]. The explosive rating for the vessel, based on the Code Case, is nine (9) pounds TNT-equivalent. One explosive test consisted of a single, centrally located, 7.2 pound bare charge of Composition C-4 (equivalent to 9 pounds TNT). The other test used six each 1.2 pound charges of Composition C-4 (7.2 pounds total) distributed in two bays of three.Copyright

Experience with Using Code Case 2564 to Design and Certify an Impulsively Loaded Vessel.

Code Case 2564 for the design of impulsively loaded vessels was approved in January 2008. In 2010 the US Army Non-Stockpile Chemical Materiel Program, with support from Sandia National Laboratories, procured a vessel per this Code Case for use on the Explosive Destruction System (EDS). The vessel was delivered to the Army in August of 2010 and approved for use by the DoD Explosives Safety Board in 2012. Although others have used the methodology and design limits of the Code Case to analyze vessels, to our knowledge, this was the first vessel to receive an ASME explosive rating with a U3 stamp. This paper discusses lessons learned in the process. Of particular interest were issues related to defining the design basis in the User Design Specification and explosive qualification testing required for regulatory approval. Specifying and testing an impulsively loaded vessel is more complicated than a static pressure vessel because the loads depend on the size, shape, and location of the explosive charges in the vessel and on the kind of explosives used and the point of detonation. Historically the US Department of Defense and Department of Energy have required an explosive test. Currently the Code Case does not address testing requirements, but it would be beneficial if it did since having vetted, third party standards for explosive qualification testing would simplify the process for regulatory approval.Copyright

Preliminary performance assessment of biotoxin detection for UWS applications using a MicroChemLab device.

In a multiyear research agreement with Tenix Investments Pty. Ltd., Sandia has been developing field deployable technologies for detection of biotoxins in water supply systems. The unattended water sensor or UWS employs microfluidic chip based gel electrophoresis for monitoring biological analytes in a small integrated sensor platform. This instrument collects, prepares, and analyzes water samples in an automated manner. Sample analysis is done using the {mu}ChemLab{trademark} analysis module. This report uses analysis results of two datasets collected using the UWS to estimate performance of the device. The first dataset is made up of samples containing ricin at varying concentrations and is used for assessing instrument response and detection probability. The second dataset is comprised of analyses of water samples collected at a water utility which are used to assess the false positive probability. The analyses of the two sets are used to estimate the Receiver Operating Characteristic or ROC curves for the device at one set of operational and detection algorithm parameters. For these parameters and based on a statistical estimate, the ricin probability of detection is about 0.9 at a concentration of 5 nM for a false positive probability of 1 x 10{sup -6}.

Code Case Validation of Impulsively Loaded EDS Subscale Vessel.

The Explosive Destruction System (EDS) was developed by Sandia National Laboratories for the US Army Product Manager for Non-Stockpile Chemical Materiel (PMNSCM) to destroy recovered, explosively configured, chemical munitions. PMNSCM currently has five EDS units that have processed over 850 items. The system uses linear and conical shaped charges to open munitions and attack the burster followed by chemical treatment of the agent. The main component of the EDS is a stainless steel, cylindrical vessel, which contains the explosion and the subsequent chemical treatment. Extensive modeling and testing have been, and continue to be used, to design and qualify the vessel for different applications and conditions. This has included explosive overtests using small, geometrically scaled vessels to study overloads, plastic deformation, and failure limits. Recently the ASME Task Group on Impulsively Loaded Vessels has developed a Code Case under Section VIII Division 3 of the ASME Boiler and Pressure Vessel Code for the design of vessel like the EDS. In this article, a representative EDS subscale vessel is investigated against the ASME Design Codes for vessels subjected to impulsive loads. Topics include strain-based plastic collapse, fatigue and fracture analysis, and leak-before-burst. Vessel design validation is based on model results, where the high explosive (HE) pressure histories and subsequent vessel response (strain histories) are modeled using the analysis codes CTH and LS-DYNA, respectively.Copyright

Response of the Explosive Destruction System Containment Vessel to Internal Detonations

The Explosive Destruction System (EDS) is a transportable system used by the Army to destroy recovered, explosively configured, chemical munitions. The system uses shaped charges to detonate the burster explosives and to cut the munition and access the agent, all inside of a sealed, stainless-steel, containment vessel. Sandia has built four EDS systems. The largest system, with an internal volume of about 620 liters, was designed to handle munitions as large as 8-inch artillery shells. This paper presents an overview of the system with emphasis on the response of the cylindrical vessel to internal detonations. The vessel response was determined through a combination of full-scale testing, sub-scale testing, and computer simulation. Tests with both bare charges and munitions have been conducted in seven vessels ranging in diameter from 19 to 91 centimeters. The paper discusses dynamic strain measurements on the vessel wall and scaling relationships associated with different sized vessels and different quantities of explosives.Copyright