High aspect ratio nickel microfluidic columns were fabricated using the LiGA technique. The 2-m-long 50-mum-wide high aspect ratio columns will be the separation component of a handheld gas chromatograph device for detecting semivolatile and volatile compounds. As a first step, 600-mum-deep electrodeposited nickel columns were fabricated. The serpentine columns were sealed and pressure-flow rate characteristics compared with the theoretical values. The response of the sealed columns was studied by running methane gas plugs through uncoated columns with a flame ionization detector at the exit. Negligible flow-induced dispersion was observed in the sealed metal columns. Unretained peak widths of ~15 ms were measured, and the experimental pressure and flow rate distributions matched those predicted by established analytical models within plusmn2.5%. Columns were coated with OV-1 stationary phase using static coating methods. A mixture of four hydrocarbons C6, C8, C10, and C12 was separated in a coated 50 mum by 600 mum by 0.5 m column in less than 2 s at 70 degC

Fabrication and Preliminary Results for LiGA Fabricated Nickel Micro Gas Chromatograph Columns

A continuous flow polymerase chain reaction (CFPCR) system was designed, fabricated from molded polycarbonate, and tested. Finite element modeling was used to simulate the thermal and Microfluidic response of the system. The mold insert for the initial prototypes was fabricated using the X-ray LIGA microfabrication process and device components produced by hot embossing polycarbonate. Commercial thin film heaters under PID control were used to supply the necessary heat flux to maintain the steady-state temperatures in the PCR.
The simulated transient temperature response at start up was compared to the experimental response. The simulated steady state temperature profile along the channel generated by the finite element analysis was compared to the experimental temperature profile displayed by liquid crystals. Experimental and simulated results were within 5% of each other, validating the thermal design of the CFPCR device.

Modeling and validation of a molded polycarbonate continuous-flow polymerase chain reaction devic

The dynamic effects of muscle strength, timing of muscle activations, and body geometry have been modeled for a wide variety of human activities These types of models require the development of complex system equations that account for the effects of rigid-body dynamics, musculotendon actuators, passive and active resistance to motion, and other physiological structures One way in which model refinement can be expedited is through the use of bond graph modeling techniques While bond graph techniques have been used extensively in a broad variety of applications, they have been used only sparingly in the field of biomechanics, despite the potential suitability of a modular, multidomain approach to the modeling of musculoskeletal function In the current paper, bond graph modules representing muscle function and rigid-body motions of underlying bone structures are introduced The system equations generated with the use of these models are equivalent to those developed with more traditional techniques, but the modules can be more easily used in conjunction with control models of neuromuscular function for the simulation of overall dynamic motor performance

Modeling of musculoskeletal structure and function using a modular bond graph approach

In combination with tapered-trench-etching of Si and SU-8 photoresist, a grayscale mask for deep X-ray lithography was fabricated and passed a 10-times-exposure test. The performance of the X-ray grayscale mask was evaluated using the TERAS synchrotron radiation facility at the National Institute of Advanced Industrial Science and Technology (AIST). Although the SU-8 before photo-curing has been evaluated as a negative-tone photoresist for ultraviolet (UV) and X-ray lithographies, the characteristic of the SU-8 after photo-curing has not been investigated. A polymethyl methacrylate (PMMA) sheet was irradiated by a synchrotron radiation through an X-ray mask, and relationships between the dose energy and exposure depth, and between the dose energy and dimensional transition, were investigated. Using such a technique, the shape of a 26-μm-high Si absorber was transformed into the shape of a PMMA microneedle with a height of 76 μm, and done with a high contrast. Although during the fabrication process of the X-ray mask a 100-μm-pattern-pitch (by design) was enlarged to 120 μm. However, with an increase in an integrated dose energy this number decreased to 99 μm. These results show that the X-ray grayscale mask has many practical applications. In this paper, the author reports on the evaluation results of SU-8 when used as a membrane material for an X-ray mask.

Performance of SU-8 Membrane Suitable for Deep X-Ray Grayscale Lithography

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Design and microfabrication of a molded polycarbonate continuous flow polymerase chain reaction device

Masks made from graphite stock material have been demonstrated as a cost-effective and reliable method of fabricating X-ray masks for deep and ultra-deep x-ray lithography (DXRL and UDXRL, respectively). The focus on this research effort was to fabricate masks that were compatible with the requirements for deep and ultra deep X-ray lithography by using UV optical lithography and gold electroforming. The major focus was on the uniform application of a thick resist on a porous graphite substrate. After patterning the resist, gold deposition was performed to build up the absorber structures using pulsed- electroplating. In this paper we will report on the current status of the mask fabrication process and present some preliminary exposure results.

Fabrication of graphite masks for deep and ultradeep x-ray lithography

An apparatus for testing a subterranean formation penetrated by a wellbore, comprising a tool having a sample flow line an inlet disposed with the tool and configured to establish fluid communication between the formation and the sample flow line to draw a fluid sample into the sample flow line, and an active filter positioned in the sample flow line and providing a filter flow route and a bypass flow route in the sample flow line.

Downhole fluid filter

Downhole tool fluid flow control apparatus including a first fluid valve between a first portion of a first flowline and a second portion of a second flowline. The first and second flowlines are adjacent each other. A second fluid valve is between a second portion of the first flowline and a first portion of the second flowline. The first and second fluid valves are controllable to cause fluid flow between the first portion of the first flowline and the second portion of the second flowline or between the first portion of the second flowline and the second portion of the first flowline.

Fluid control modules for use with downhole tools

An instrument to estimate the dynamic properties of articular cartilage in vivo is proposed. Through the use of a mechanical indenter adapted from in vitro testing methods and an ultrasound data acquisition system, a time constant for articular cartilage can be obtained. Dynamic lumped parameter models of articular cartilage and the instrument were developed using bond graph techniques for evaluating the feasibility of microfabricating the tool. Simulation results showed that a characteristic time constant for cartilage reswelling could be measured using the probe. Measurement protocols were designed to isolate fluid resistance and cartilage stiffness. Scaling the size of the instrument down lowered the amplitude of the forces required to indent the cartilage and reduced the length of the time the surgeon would need to hold the instrument in a single position in order to perform a test.

Kevin J. Zanca

Papers

Fabrication of graphite masks for deep and ultradeep x-ray lithography

Downhole fluid filter

Fluid control modules for use with downhole tools

Design of an arthroscopic instrument for dynamic testing of articular cartilage properties