A micro optofluidic splitter and switch based on hydrodynamic spreading

Abstract

This paper presents the fabrication and characterization of a silicon-based optofluidic device for switching and splitting of a core stream with fluorescent dyes. The dye laser was created in the core, which is excited by a blue wavelength. The streams in the microchannel also form a liquid-core/liquid-cladding wave guiding system. The core is a glycerol solution, while the cladding is formed by two sheath streams of deionized water. The higher refractive index of the glycerol solution keeps the laser light inside the liquid core through total internal reflection. Keeping the flow rate of the core stream constant, splitting and switching was realized by controlling the flow rate ratio between the two sheath streams. The width of the core was controlled by hydrodynamic spreading or by the ratio between the core stream and the sheath streams. The fastest switching speed was about 300 ms, which is limited only by the response time of the pumping system. The wave guiding capability of this system was tested by coupling laser signals in and out of the fluidic system and measuring their intensity. The concepts and devices presented in this paper are suitable for applications with hydrodynamic focusing, sorting and optical detection for feed-back control.

Modular Platforms for Optofluidic Systems

“…Furthermore, the basic elements of optical platforms have been developed with optofluidic principles, namely waveguides [88][89][90][91][92][93][94] and optical switches [95][96][97][98][99]. The optofluidic switch has even reached industrial level (Agilent Photonic Switching Platform).…”

Optofluidics incorporating actively controlled micro- and nano-particles

“…121,122 Such lenses have been used as manipulators of light exhibiting the ability to control the amplitude, phase, and polarization properties of light and its directions of propagation. [123][124][125][126][127] Beam control was demonstrated by displacing optically trapped particles such as an SiO 2 (Ø13 lm) microsphere through a light beam. beam to be refracted by various degrees as a function of the particle position, providing tuneable attenuation and beam-steering in the device.…”

Microfluidic switch based on combined effect of hydrodynamics and electroosmosis

“…Soft lithography technique was used to fabricate the microchannel in PDMS (Nguyen 2006). The layout shown in Fig.…”

“…The response time is an important parameter for switching techniques. Wolfe et al (2004) reported switching with a response time of 2 s. The response time reported by Campbell et al (2004) was 20 ms. Hydrodynamic switching reported by Nguyen et al (2007) has a response time of 0.3 s. Tan and Lee (2005) and Huh et al (2007) reported that microfluidic devices can be used to separate droplets using hydrodynamic effect. A cell counting and sorting system which can be used as cytometer was designed by Yang et al (2006), the cell can be sorted at a frequency of 120 cells min -1 .…”