Tunable microfluidic optical devices with an integrated microlens array

Abstract

The interest in dynamically tuning light has attracted great attention to the fabrication of tunable microlens arrays. Here we discuss the fabrication and characterization of a simple, robust, yet tunable microfluidic optical device with integrated microlens array. The microfuidic device with desired channel structure was micromachined on a polycarbonate plate with a resolution up to 100 µm, followed by thermal bonding two plates above their glass transition temperature. The microlens arrays were replica molded on a glass slide, which was then attached to the polycarbonate plates. By simply actuating the liquids with variable refractive index into the fluidic channel to immerse the lens arrays without moving or deformation of microlenses, a large change of focal length of more than 10 times (ƒ=0.74 to 8.53) was achieved. When a dye-containing liquid was pumped into the microfluidic channel to cover the lenses, the light transmission through the lenses was reduced from about 95% to 55% when the dye concentration was increased to 10 w/v %. The knowledge we gain from these studies will provide important insights to contruct new, adaptive, micro-scale optical devices with multiple functionalities. 2 AbstractThe interest in dynamically tuning light has attracted great attention to the fabrication of tunable microlens arrays. Here we discuss the fabrication and characterization of a simple, robust, yet tunable microfluidic optical device with integrated microlens array. The microfluidic device with desired channel structure was micromachined on a polycarbonate plate with a resolution up to 100 μm, followed by thermal bonding two plates above their glass transition temperature. The microlens arrays were replica molded on a glass slide, which was then attached to the polycarbonate plates. By simply actuating the liquids with variable refractive index into the fluidic channel to immerse the lens arrays without moving or deformation of microlenses, a large change of focal length of more than 10 times (f = 0.74 to 8.53) was achieved. When a dye-containing liquid was pumped into the microfluidic channel to cover the lenses, the light transmission through the lenses was reduced from about 95% to 55% when the dye concentration was increased to 10 w/v %. The knowledge we gain from these studies will provide important insights to construct new, adaptive, micro-scale optical devices with multiple functionalities.

Phototunable Microlens Array Based on Polymer Dispersed Liquid Crystals

“…Several research groups have created a structure similar to the brittlestar based on a microfluidic system. [21][22][23][24] The dye-containing liquid in the microchannels was used to tune the light transmission in the microlens array (MLA). However, these MLAs have a complicated structure and multiple steps are involved in their fabrication.…”

Microcapillary electrophoresis chips utilizing controllable micro‐lens structures and buried optical fibers for on‐line optical detection

“…In recent years, polymer micro-lens has been widely utilized for light focusing of the excitation light source and fluorescent emission due to its good optical properties and easier fabrication process. The micro-lens can be placed on the top of the microfluidic device [21][22][23], or inside microchannels [11,24]. Basically, micro-lens can be divided into two categories, namely fixed-focal-length [18,20] and variable-focal-length micro-lens [25,26].…”

A pH-tunable hydrogel microlens array with temperature-actuated light-switching capability

“…[10][11][12][13] More recently, several groups have used environmentally sensitive hydrogels to modulate the focal length. This has been accomplished by either varying the curvature of a liquid-liquid interface 14 or encapsulating temperaturesensitive hydrogel in an artificial shell ͑polystyrene or thin silicone membrane͒ and providing an external physical actuation source.…”