Our development of ultra light-weight X-ray micro pore optics based on MEMS (Micro Electro Mechanical System)
technologies is described. Using dry etching or X-ray lithography and electroplating, curvilinear sidewalls
through a flat wafer are fabricated. Sidewalls vertical to the wafer surface are smoothed by use of high temperature
annealing and/or magnetic field assisted finishing to work as X-ray mirrors. The wafer is then deformed to
a spherical shape. When two spherical wafers with different radii of curvature are stacked, the combined system
will be an approximated Wolter type-I telescope. This method in principle allows high angular resolution and
ultra light-weight X-ray micro pore optics. In this paper, performance of a single-stage optic, coating of a heavy
metal on sidewalls with atomic layer deposition, and assembly of a Wolter type-I telescope are reported.
Microelectromechanical systems (MEMS) micropore X-ray optics were proposed as an ultralightweight, high-
resolution, and low cost X-ray focusing optic alternative to the large, heavy and expensive optic systems in
use today. The optic's monolithic design which includes high-aspect-ratio curvilinear micropores with minimal
sidewall roughness is challenging to fabricate. When made by either deep reactive ion etching or X-ray LIGA, the
micropore sidewalls (re
ecting surfaces) exhibit unacceptably high surface roughness. A magnetic eld-assisted
nishing (MAF) process was proposed to reduce the micropore sidewall roughness of MEMS micropore optics
and improvements in roughness have been reported. At this point, the best surface roughness achieved is 3
nm Rq on nickel optics and 0.2 nm Rq on silicon optics. These improvements bring MEMS micropore optics
closer to their realization as functional X-ray optics. This paper details the manufacturing and post-processing
of MEMS micropore X-ray optics including results of recent polishing experiments with MAF.
Portable blood analysis devices are usually appreciable for applications in blood diagnostic system. We have designed and fabricated a low-cost and simple deal blood extraction device for a biomedical analysis. The device mainly composes of blood extraction tool and a functional bio-chemical analyzing element. In this work, we report the fabrication and pressure-gradient testing results of the blood extraction tool which consists of painless microneedle array and pressure-gradient tank. Microneedle array was fabricated by X-ray lithography using PCT (Plane-pattern to Cross-section Transfer) technique. The idea of our extraction device was simple but capability which is just to hold a sufficient pressure gradient between the tank and blood vessel. The device can draw the volume of blood up to 237 μl. The device was made of low-cost and disposable materials since it is expected to be used for single blood analysis system. In this work, we introduce design, fabrication and mechanism of the pressure gradient driven component including the extraction test results. The fabrication method of microneedle used in our system is also described.
Simulations for deformed shape-predictions of the 3-dimensional microstructures fabricated by Plane-pattern to Crosssection Transfer (PCT) Technique and Synchrotron Radiation (SR) lithography are described in this paper. We have attempted to study on a nonlinear relation between X-ray dosage and depth of the structure in the past work. The shapeprediction was investigated from two pairs of parameters influencing the structural deformation; dose-depth and
position-dose. However, the above simulations resulted as, the higher height of the structure, the more error margin observed. A possible cause could be the etching direction dependent on the developing time. Thus, we currently emphasize on the factor causing this error. In order to comprehend the mechanism of the factor, the mathematical
system of X-ray energy distribution onto PMMA (poly-methylmethacrylate) resist has been developed. The shape-prediction is consequent of the simulations based on calculations from the mathematics software. The investigation of the system enhances a possibility for higher accuracy of the prediction. In addition, the desired shapes can be confirmed by the simulations before the mask design and running experiments. The mathematical system for energy distribution dependents 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. The simulations for shape-prediction were completed by the above parameter sets with the simulation software, MATHEMATICA(R). Graphic displays of predicted shapes are provided in the paper for clearly understanding.
Painless and portable blood extraction device has been immersed in the world of miniaturization on bio-medical research particularly in manufacturing point-of-care systems. The fabrication of a blood extraction device integrated with an electrolyte-monitoring system is reported in this paper. The device has advantages in precise controlled dosage of blood extracted including the slightly damaged blood vessels and nervous system. The in-house blood diagnostic will become simple for the patients. Main components of the portable system are; the blood extraction device and electrolyte-monitoring system. The monitoring system consists of ISFET (Ion Selective Field Effect Transistor) for measuring the concentration level of minerals in blood. In this work, we measured the level of 3 ions; Na+, K+ and Cl-. The mentioned ions are frequently required the measurement since their concentration levels in the blood can indicate whether the kidney, pancreas, liver or heart is being malfunction. The fabrication of the whole system and experimentation on each ISM (Ion Sensitive Membrane) will be provided. Taking the advantages of LIGA technology, the 100 hollow microneedles fabricated by Synchrotron Radiation deep X-ray lithography through PCT (Plane-pattern to Cross-section Transfer) technique have been consisted in 5x5 mm2 area. The microneedle is 300 μm in base-diameter, 500 μm-pitch, 800 μm-height and 50 μm hole-diameter. The total size of the blood extraction device is 2x2x2 cm3. The package is made from a plastic socket including slots for inserting microneedle array and ISFET connecting to an electrical circuit for the monitoring. Through the dimensional design for simply handling and selection of disposable material, the patients can self-evaluate the critical level of the body minerals in anywhere and anytime.
The paper describes about a useful study on the deformed shapes of microstructures fabricated by PCT (Plane-pattern to Cross-section Transfer) Technique. Previously, we have introduced the PCT technique as an additional process to conventional X-ray lithography for an extension of 2.5-dimensional structure to 3-dimensional structure. The PMMA (poly-methylmethacrylate) has been used as the X-ray resist. So far, microneedle and microlens arrays have been successfully fabricated in various shapes and dimensions. The production cost of X-ray mask has been known as the most expensive process for LIGA step, therefore, to predict the resulting shapes of structure precisely before fabricating the mask is relatively important. Although, the 2-D pattern on the X-ray mask can form a similar shape resulting in 3-D structure, the distorted shapes of microstructures have been observed. A linear-edged pattern on the X-ray mask resulted as an exponential-edged structure and an exponential-edged pattern resulted as an exceeding curvature, for example. This problem causes a change in the functional property of the array. In the case of our microneedle array, the linear-edge is highly required since it increases the strength of microneedle. We have investigated and suggested a calculation method fir a shape-prediction of microstructure fabricated by PCT technique in this work. The compensation calculation by our theories for an X-ray mask design can solve the undesired shape resulting after X-ray exposure. Moreover, the dosage control and suitable developing time are given in order to see through the current condition of the currently used synchrotron radiation light-source.