Online Quality Assurance of Microchannels in Roll-to-Roll by Optical Coherence Tomography

Abstract

Roll-to-roll (R2R) process is an emerging technology to manufacture printed electronics, microfluidics, biochemical sensors etc. The requirements for high quality and small tolerances at the manufacturing phase are of the essence for such products. To verify the quality and guarantee the high production yield, high speed, non-destructive testing methods are needed. In this paper, optical coherence tomography (OCT) device is used at the R2R-line to measure online hot embossed microchannel structures at speed of 1 m/min, which is typical for the hot embossing process. The channel's width and shape are determined along the web. The applicability of OCT for topography measurements is demonstrated in an actual R2R environment.

Wavelength Scanning Interferometry for Topography of Microchannels at Roll-to-Roll Line with Optical Coherence Tomography

“…The WSI processing algorithm was applied to determine surface position at nanometer-scale resolution. This improved the resolution compared to the method based on only the maximum intensity [22], of which resolution was, without zero padding, 2.7 µm (2.7 mm/1024). The heights and widths were automatically determined for two different hot embossing pressures.…”

“…We have recently applied OCT for surface topography measurements at the R2R-line [22], however, in those measurement OCT suffered from the poor depth resolution due to the lack of WSI capability, and therefore, heights of the channels were not determined. In this study, we use a WSI algorithm to obtain surface topography at nanometerscale resolution without losing micrometer resolution tomography information.…”

Real‐Time Metrology for Roll‐To‐Roll and Advanced Inline Manufacturing: A Review

“…Optical Coherence Tomography (2.10) Thickness, Internal topography, refractive index [34] Polymers, semitransparent films, biological samples 1 m min −1 (not including data processing) [34] 1D OCT: frame rate of 97.66 fps; 3D OCT prototype: frame rate of 30.6 fps. [35] Vertical resolution: 5.8 microns; Lateral resolution: 91 microns @ web speed of 1 m min Has significant potential for R2R applications as it can be used in reflection and transmission mode [36] and complete probe/sensor can be integrated into a compact fiber package.…”

“…Lauri, J. et al (2019) demonstrated OCT for inline R2R monitoring of the structure of hot-embossed microchannel in PMMA webs. [34] For static offline measurement, the commercial Thorlabs OCT system used is capable of vertical (depth) resolution of 5.8 µm (in air) and lateral resolution of 8 µm. For inline measurement, the effective lateral resolution in the longitudinal direction was 91 µm.…”

Capillary Filling in Open Rectangular Microchannels with a Spatially Varying Contact Angle

“…Because the channel is open to the atmosphere, nanoparticles can be deposited in microchannels by evaporating a colloidal suspension. This strategy has been applied to the fabrication of printed electronic devices, such as conductors, resistors, and low-pass filters, − where open rectangular microchannels were used due to their ease of fabrication. Printed electronic devices are of considerable technological importance because they are low-cost, flexible, and light. − Additionally, open rectangular microchannels appear in microfluidic devices for applications, such as heat pipes , and artificial lungs .…”