Micro-area fluid measurement Micro PIV/Micro LIF

Micro PIV and micro LIF are systems for analyzing the flow velocity distribution, mixing, and diffusion of microfluidics (microfluidics). A system is constructed by combining optical systems such as a microscope and components for micro PIV such as dedicated tracer particles. It is widely used in the development of micro biochemical chips called micro TAS and lab-on-chip in recent years.
Some links lead to Japanese pages.

In addition to conventional double pulse type micro PIV (2D, stereo 3D), time series micro PIV, we have a lineup of various types of micro PIV systems such as confocal scanning micro PIV. The dedicated micro-optical system has a lineup of models that are compatible with high-power pulse lasers and UV lasers. Peripheral equipment such as a focus scanner that can scan the focal plane at high speed synchronously with the high-speed video frame is also available. We also have a wide variety of fluorescent particles, which are indispensable for micro PIV, that are optimal for tracers, and can be selected according to color, size, and target fluid (water, organic solvent, etc.).

Micro LIF can measure concentration distribution, temperature distribution, diffusion, mixing, reaction, pH, etc. The dedicated micro-optical system can co-axially illuminate a high-power UV pulse laser, which is not possible with general microscopes.

System configuration example
■Double shutter type LIF camera
■Double pulse laser 30mJ/pulse 15Hz 532nm
■Timing controller
■Micro optical system, fiber bundle delivery type
■Control analysis software Koncerto II LIF
■PC for control analysis

Confocal micro PIV/LIF is a system that enables high-precision measurement by increasing the resolution in the Z-axis direction by using a confocal scanner in addition to the optical system of a normal microscope.
Why is confocal imaging effective in microimaging?
Micro PIV uses the concept of measurement depth (MD) instead of depth of field (DOF) when defining Z-direction resolution.
This is a concept proposed by Minehart et al., UC Santa Barbara, and refers to the range in which the light intensity of the particle image appears strong enough to affect velocity measurements, and is generally much thicker than the DOF. In a normal micro PIV, the MD is much thicker than the designed depth of focus of the objective lens, and different velocity components are mixed within the thickness of the MD, resulting in measurement errors. (see figure), on the other hand, in confocal scanning micro PIV, it is possible to make the MD thin so that only a single velocity component is included in the MD area, enabling high-precision measurement distribution in microfluidics. rice field.

Micro LIF usually does not use fluorescent particles, but rather uses a fluorescent agent dissolved in a liquid, and the liquid itself emits light. Therefore, in normal microscope observation, even if a high-NA objective lens is used, fluorescence emission in front of and behind the focal plane enters as stray light, lowering the spatial resolution in the optical axis direction (Z direction). (The spatial resolution in the XY direction is significantly lower than the spatial resolution in the Z direction.) With confocal imaging, the fluorescence emission in front of and behind the focal plane can be almost completely cut off, resulting in a high Z-direction resolution that matches the XY-direction resolution. It can be obtained.

System configuration example

■ Ultra-sensitive high-speed video camera
■ Confocal scanner CSU-X1
■ CW DPSS Laser 100mW 488nm
■ Focus scanner FS-100 (option)
■ Micro optical system UFS-200 Fiber bundle delivery type
■ Control analysis software Koncerto II
■ PC for control analysis

A high-speed microimaging piezofocus scanner suitable for use with high-speed video and confocal scanners. It is installed between the microscope body and the objective lens. This unit scans the observation surface at high speed by moving the objective lens up and down at high speed.