Micro Fluidic Channel Machining on Fused Silica Glass Using Powder Blasting

Abstract

In this study, micro fluid channels are machined on fused silica glass via powder blasting, a mechanical etching process, and the machining characteristics of the channels are experimentally evaluated. In the process, material removal is performed by the collision of micro abrasives injected by highly compressed air on to the target surface. This approach can be characterized as an integration of brittle mode machining based on micro crack propagation. Fused silica glass, a high purity synthetic amorphous silicon dioxide, is selected as a workpiece material. It has a very low thermal expansion coefficient and excellent optical qualities and exceptional transmittance over a wide spectral range, especially in the ultraviolet range. The powder blasting process parameters affecting the machined results are injection pressure, abrasive particle size and density, stand-off distance, number of nozzle scanning, and shape/size of the required patterns. In this study, the influence of the number of nozzle scanning, abrasive particle size, and pattern size on the formation of micro channels is investigated. Machined shapes and surface roughness are measured using a 3-dimensional vision profiler and the results are discussed.

Keywords: Bio sensor; Fuel cell; Fused silica glass; Lab-on-a- chip; Micro Fluidic channel; Micro powder blasting.

Figure 1.

Basic material removal mechanism of powder blasting.

Figure 2.

Patterning process by powder blasting.

Figure 3.

Designed pattern and masked specimen.

Figure 4.

3-dimensional shapes and cross-sectional profiles of masked patterns. (vertical scale=20μm, horizontal scale=50μm)

Figure 5.

SEM micrographs of used abrasive particles.

Figure 6.

3-dimensional shapes and cross-sectional profiles of 200μm channels using WA#600 abrasive. (vertical scale=20μm, horizontal scale=50μm)

Figure 7.

3-dimensional shapes and cross-sectional profiles of 200μm channels using WA#1200 abrasive. (vertical scale=20μm, horizontal scale=50μm)

Figure 8.

Top-view images of machined patterns. (300μm WA#600, 20 scanning)

Figure 9.

Top-view images of machined patterns. (300μm WA#1200, 20 scanning)

Figure 10.

Machined shape variations when nozzle scanning count is 5, 10, 15, 20. (vertical scale=20μm, horizontal scale=50μm)

Figure 11.

Channel depth variations according to the number of nozzle scanning.

Figure 12.

Channel width variations according to the number of nozzle scanning.