Wide Field-of-View Fluorescence Imaging with Optical-Quality Curved Microfluidic Chamber for Absolute Cell Counting

Abstract

Field curvature and other aberrations are encountered inevitably when designing a compact fluorescence imaging system with a simple lens. Although multiple lens elements can be used to correct most such aberrations, doing so increases system cost and complexity. Herein, we propose a wide field-of-view (FOV) fluorescence imaging method with an unconventional optical-quality curved sample chamber that corrects the field curvature caused by a simple lens. Our optics simulations and proof-of-concept experiments demonstrate that a curved substrate with lens-dependent curvature can reduce greatly the distortion in an image taken with a conventional planar detector. Following the validation study, we designed a curved sample chamber that can contain a known amount of sample volume and fabricated it at reasonable cost using plastic injection molding. At a magnification factor of approximately 0.6, the curved chamber provides a clear view of approximately 119 mm2, which is approximately two times larger than the aberration-free area of a planar chamber. Remarkably, a fluorescence image of microbeads in the curved chamber exhibits almost uniform intensity over the entire field even with a simple lens imaging system, whereas the distorted boundary region has much lower brightness than the central area in the planar chamber. The absolute count of white blood cells stained with a fluorescence dye was in good agreement with that obtained by a commercially available conventional microscopy system. Hence, a wide FOV imaging system with the proposed curved sample chamber would enable us to acquire an undistorted image of a large sample volume without requiring a time-consuming scanning process in point-of-care diagnostic applications.

Long-Term Tracking of Free-Swimming Paramecium caudatum in Viscous Media Using a Curved Sample Chamber

“…Using a curved image plane [ 14 , 15 ] was one of the approaches to eliminate this problem. This problem and a solution for static measurement have been demonstrated in our previous research [ 8 ] by developing curved microfluidic chambers.…”

“…The curved chamber comprises two parts: a lower substrate and an upper window. It has a spherical dome shape in both parts, and this shape depends on the lens curvature, which was extensively described in our previous research [ 8 ]. The chamber that is used herein also has a 100 µm gap between the upper and lower parts and a 12-mm diameter.…”

“…Typically, single-lens imaging system has some aberrations in the image field, but the sample can be detected if it is corrected for field curvature. The curved substrate has been proposed in our previous research [ 8 ] for demonstrating its performance of fluorescent cell imaging in comparison with a flat substrate. The proposed system does not require further image processing and can analyze the sample with an acquired single wide FOV raw image.…”

Nut and Bolt Microfluidics with Helical Minichannel for Counting CD4+ T-Cells

“…Therefore, an area of 200–300 mm 2 or more is required to accommodate 20–30 μL of the sample. To increase the sample volume to obtain the statistical significance of the measured values, the samples included in a larger area should be photographed [9]. Therefore, a two-axis translation stage for scanning the detection channel should be equipped [10].…”

Simulation, Fabrication and Analysis of Silver Based Ascending Sinusoidal Microchannel (ASMC) for Implant of Varicose Veins

“…Alshare et al (2016) analyzed heat transfer and gaseous flow in sinusoidal microchannels with the help of computational modeling [ 43 ]. Many researchers have performed investigation on microneedles, micropumps, microchambers, microsensors, and micromixers, for biomedical and other applications [ 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 ].…”