Novel Optofluidic Imaging System Integrated with Tunable Microlens Arrays

Abstract

Optofluidic tunable microlens arrays (MLAs) can manipulate and control light propagation using fluids. Lately, their applicability to miniature lab-on-a-chip systems is being extensively researched. However, it is difficult to incorporate 3D MLAs directly in a narrow microfluidic channel using common techniques. This has resulted in limited research on variable focal length imaging with optofluidic 3D MLAs. In this paper, we propose a method for fabricating MLAs in polydimethylsiloxane (PDMS)-based microchannels via electrohydrodynamic jet (E-jet) printing to achieve optofluidic tunable MLAs. Using this method, MLAs of diameters 15 to 80 μm can be fabricated in microfluidic channels with widths of 200 and 300 μm. By alternately using solutions with different refractive indices in the microchannel, the optofluidic microlenses exhibit reversible modulation properties while retaining the morphologies and refractive indices of the microlenses. The focal length of the resulting optofluidic chip can have threefold tunability, thereby achieving an imaging depth of approximately 450 μm. This outstanding advantage is useful in observing microspheres and cells flowing in the microfluidic system. Thus, the proposed optofluidic chip exhibits great potential for cell counting and imaging applications.

Biomimetic Compound Eyes with Gradient Ommatidium Arrays

“…A large number of gradient ommatidia are closely arranged in a honeycomb pattern on the surface of the compound eye, allowing the compound eye to achieve the continuous change of focal length. Compared with the works of some novel adjustable compound eyes and adjustable lens arrays that need to rely on external pumps to achieve focal length adjustment, 48 gradient compound eye depends on its numerous gradient ommatidia to achieve continuous change of focal length and, thus, its size is extremely small.…”

Reconfigurable Microlens Array Enables Tunable Imaging Based on Shape Memory Polymers

“…Microlens arrays (MLAs) that consist of hundreds of microscale lenslets have been considered as a typical kind of optical element with a small size and high integration. To date, MLAs have found broad applications in optical imaging, − 3D display, , infrared guidance, and optical sensing. − In some advanced optical systems, MLAs usually play an essential role in achieving their advanced optical performance. Each microlens unit of an MLA operates independently and works as a whole, which enables light manipulation, optical phase modulation, resolution improvement, and aberration correction.…”

“…In addition to the mechanical modulation, the imaging performance can also be tuned by varying the refractive index of the MLAs. By introducing liquids with different refractive indices into microfluidic chips, the focal length of MLA can be quickly tuned. , As a very important type of tunable MLA, the liquid crystal MLAs also permit dynamic modulation of their imaging performance. , Liquid crystal molecules with a tunable refraction functionalize as active optical components for imaging. The tuning mechanisms include electrical, thermal, and chemical modulation and other methods, holding great promise for practical applications .…”

Concave microlens arrays with tunable curvature for enhanced photodegradation of organic pollutants in water: A non‐contact approach

“…4,5 Microlenses (MLs) have emerged as a promising technology to enhance energy transfer efficiency by optimizing light inside of the solar-driven reactors. [6][7][8][9] The near-field effect of MLs enables the strong focusing effects in a short distance around the MLs, 10,11 which has been widely applied in the fields where high light harvesting efficiency [12][13][14][15][16][17] and minimized dimensions [18][19][20] are required. The focal distance of typical convex MLs is in the scale of micrometers, 11,21,22 so they have to be implemented inside of a reactor to make focal points located inside water.…”