Measurement of buried undercut structures in microfluidic devices by laser fluorescent confocal microscopy

Li, Shiguang; Liu, Jing; Nguyen, Nam‐Trung; Fang, Zhijie; Yoon, Soon Fatt

doi:10.1364/ao.48.006432

Cited by 3 publications

(3 citation statements)

References 53 publications

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“…The patterned surface and the PDMS cover layer were treated for 30 s at the power of 100 W oxygen plasma, and then were immediately joined together. In order to strengthen the bonding quality, the sample was placed into an oven for 15 min at 80 • C. 15 The detailed bonding parameters are listed in Table 1.…”

Section: Inspection For Plasma Bondingmentioning

confidence: 99%

Feasibility study on bonding quality inspection of microfluidic devices by optical coherence tomography

Yoon

et al. 2011

J. Biomed. Opt.

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This paper reports the feasibility of optical coherence tomography (OCT) technology for inspection of bonding quality of microfluidic devices in manufacturing environments. A compact optical-fiber-based OCT is developed and its measurement performance is characterized. A series of microfluidic devices respectively bonded by adhesive tape, thermal method, and oxygen plasma, are inspected. The defects of geometry deformation and sealing completeness are emphasized during measurements. Based on the inspection results, some discoveries related to the production of microfluidic devices are discussed.

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Section: Inspection For Plasma Bondingmentioning

confidence: 99%

Feasibility study on bonding quality inspection of microfluidic devices by optical coherence tomography

Yoon

et al. 2011

J. Biomed. Opt.

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“…One challenge all techniques face is the limiting effect of optical distortion caused by the microfluidic device features on quantitative accuracy of the measurement. The microfluidic device‘s interfaces introduce spherical aberration and affect the effective depth to which the beam(s) focuses, the confocal volume changes as a function of depth, and a reduced collection efficiency often results, leading to “dark” or “hidden” regions within the image. − Curved surfaces can additionally introduce lensing effects. The specific relationship between channel position and optical aberration depends on the channel depth, the numerical aperture of the illumination/collection optics, the refractive indices of the chip material and the fluid, and the shape of the interface (Figure a), making quantitative measurements difficult.…”

mentioning

confidence: 99%

Quantitative Chemical Imaging of Nonplanar Microfluidics

et al. 2017

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Confocal and multiphoton optical imaging techniques have been powerful tools for evaluating the performance of and monitoring experiments within microfluidic devices, but this application suffers from two pitfalls. The first is that obtaining the necessary imaging contrast often requires the introduction of an optical label which can potentially change the behavior of the system. The emerging analytical technique stimulated Raman scattering (SRS) microscopy promises a solution, as it can rapidly measure 3D concentration maps based on vibrational spectra, label-free; however, when using any optical imaging technique, including SRS, there is an additional problem of optical aberration due to refractive index mismatch between the fluid and the device walls. New approaches such as 3D printing are extending the range of materials from which microfluidic devices can be fabricated; thus, the problem of aberration can be obviated simply by selecting a chip material that matches the refractive index of the desired fluid. To demonstrate complete chemical imaging of a geometrically complex device, we first use sacrificial molding of a freeform 3D printed template to create a round-channel, 3D helical micromixer in a low-refractive-index polymer. We then use SRS to image the mixing of aqueous glucose and salt solutions throughout the entire helix volume. This fabrication approach enables truly nonperturbative 3D chemical imaging with low aberration, and the concentration profiles measured within the device agree closely with numerical simulations.

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“…(TD220, Tektronix, USA) was used for collecting the electrical signal and converts it to a waveform, which was subsequently transferred to the PC via the serial interface. The channel dimension after bonding was measured with a confocal microscopy system [193]. The confocal microscopy is an optical imaging technique that can measure embedded micro-features bonded to a cover layer.…”

Section: Methodsmentioning

confidence: 99%

Investigation of multiphase liquid systems in microchannels

Liu¹

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Droplet-based microfluidics plays an important role in biological and chemical sciences. Different operations such as transport, reagent reaction, particles sorting, and merging can be achieved within a confined droplet. Droplet manipulation can be achieved in a passive or active way. The passive way focuses on the ingenious device design and arrangement, while the active way incorporates external forces including but not limiting to thermocapillary force, electroweting effect, and magnetic force. Numerical procedures are implemented to study multiphase systems in microchannels. The combined governing equations are employed to calculate the physical fields. They are solved using a finite volume method on the uniform Cartesian grid. The interfacial tension force and the magnetic force are coupled in the Navier-Stokes equation. The interface between two phases is captured using a particle level-set method. The present numerical codes are validated to be accurate to use in the droplet-based microfluidics. In this thesis, a series of diffuser/nozzle structures is employed to investigate the behavior of microdroplets flowing in microchannels. Depending on the imposed flow direction, the serial structures can act either as a series of diffusers or nozzles. On the experimental front, the fabrication of the test devices used the soft lithography techniques in polydimethylsiloxane (PDMS). T-junctions for droplet formation, diffuser/nozzle structures and pressure ports were integrated in a single device.

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Measurement of buried undercut structures in microfluidic devices by laser fluorescent confocal microscopy

Cited by 3 publications

References 53 publications

Feasibility study on bonding quality inspection of microfluidic devices by optical coherence tomography

Feasibility study on bonding quality inspection of microfluidic devices by optical coherence tomography

Quantitative Chemical Imaging of Nonplanar Microfluidics

Investigation of multiphase liquid systems in microchannels

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