Plane-pattern To Cross-section Transfer Research Articles

Fabrication of 3-D PTFE microstructures utilising change of etching rate with respect to exposure time

In this study, we fabricated three-dimensional (3-D) polytetrafluoroethylene (PTFE) microstructures using the plane-pattern to cross-section transfer (PCT) method with synchrotron radiation (SR) ablation. We found that the etching rate increased with increasing SR exposure. This was attributed to the heating of the PTFE surface as evidenced by the emission of fluorocarbon gas from the surface. Using the PCT method, we successfully produced various 3-D PTFE microstructure shapes by varying the energy distribution of the SR exposure using multiple scanning speeds.

Shape Prediction of 3‐D Microstructures Fabricated by PCT Technique and Synchrotron Radiation Lithography

AbstractWe report in this paper simulations for deformed shape predictions of three‐dimensional (3‐D) microstructures fabricated by the plane pattern to cross‐section transfer (PCT) technique and synchrotron radiation (SR) lithography. The investigation of the shape‐prediction system enhances the possibility for higher accuracy of the prediction. In addition, the desired shapes can be confirmed by the shape prediction before designing the mask and running experiments. It is necessary to investigate a variety of error factors to shape prediction. We attempted various investigations. One of the possible causes could be the etching direction, which is dependent on the developing time. Therefore, we currently emphasize on the factor causing this error. In order to comprehend the mechanism of the factor, an algorithm that can simulate development was devised. We have developed a mathematical system of X‐ray energy distribution onto the PMMA (polymethylmethacrylate) resist, and the shape prediction is consequent to the simulations based on calculations from the mathematics software. The mathematical system for energy distribution depends on the SR light source, X‐ray mask specification, and resist specification. As a result, the predicted structures relevant to the absorbed energy–depth–position parameter set and absorbed energy–etching rate parameter set were obtained from this system. This system for shape prediction was implemented by the above parameter sets in C language. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

3-D PTFE microstructure fabricated using synchrotoron radiation etching

Microfabrication technique using SR ablation for 3-D polytetrafluoroethylene (PTFE) structure is reported in this work. First of all, we investigated necessary basic data for the fabricated structure like the processing depth and the etching rate, etc. And, the exposure energy distribution was given to the surface of polytetrafluoroethylene by using the plane pattern to cross-section transfer (PCT) technique, 3-D microstructures was fabricated. To establish three dimension of highly accurate PTFE processing technology, we are researching the application to the device.

Geometrical strengthening and tip-sharpening of a microneedle array fabricated by X-ray lithography

A novel fabrication method for LIGA (from the German “Lithographie”, “Galvanik”, and “Abformung”) microneedles with through holes is presented. Such microneedles are in demand by most bio-medical MEMS applications and in some fluidic MEMS applications. We propose a technique that combines conventional deep X-ray lithography, plane-pattern to cross-section transfer (PCT) process, and alignment X-ray lithography. The technique provides precise hole alignment with ± 3 μm tolerance. Finite-element simulations on various hole locations were performed to determine the optimum position. We previously fabricated a microneedle with a 100-μm base and a 300-μm height by a right-triangular mask. The resultant microneedle had a very sharp tip but was excessively steep, and thus resulted in a very low strength. Improved strength and tip sharpness was consequently achieved by changing the mask-pattern from a triangular pattern to a polygonal mask and changing the dimensions of the microneedle to have a 300-μm base with various heights between 350 and 800 μm. Using the proposed technique, we could produce a total of 100 hollow microneedles on a 5 × 5 mm2 chip. Moreover, we successfully fabricated sharpened microneedles that were stronger than that we have fabricated so far. The molding process or electroplating and the cost list of the LIGA microneedle will also be included.

Microneedle fabrication using the plane pattern to cross-section transfer method

In this paper, microneedle fabrication using the PCT (plane pattern to cross-sectiontransfer) method is summarized. Three types of microneedle array have been developed:the single-tip, quadruplet, and hollow microneedle arrays. A brief introduction to thefabrication process using PCT and detailed design concepts for optimizing the fabricationsteps for shape improvement of the three types of microneedle are provided. Themicroneedle structures have controllable angled sidewalls, exhibiting an extraordinarilygeometrical level of accuracy compared to what is achieved using other existingfabrication methods based on deep x-ray lithography by synchrotron radiation.Furthermore, the improvements reported in this work as compared to the results fromthe existing methods are: sharper tips for the single-tip microneedles, strengthimprovement for the quadruplet microneedles, and cost reduction for the hollowmicroneedles. Each type of microneedle was designed to serve a different biomedical need.