Samuel Yang

Sub-pixel resolving optofluidic microscope for on-chip cell imaging

We report on the implementation of a color-capable sub-pixel resolving optofluidic microscope based on the pixel super-resolution algorithm and sequential RGB illumination, for low-cost on-chip color imaging of biological samples with sub-cellular resolution.

Color Capable Sub-Pixel Resolving Optofluidic Microscope and Its Application to Blood Cell Imaging for Malaria Diagnosis

Miniaturization of imaging systems can significantly benefit clinical diagnosis in challenging environments, where access to physicians and good equipment can be limited. Sub-pixel resolving optofluidic microscope (SROFM) offers high-resolution imaging in the form of an on-chip device, with the combination of microfluidics and inexpensive CMOS image sensors. In this work, we report on the implementation of color SROFM prototypes with a demonstrated optical resolution of 0.66 µm at their highest acuity. We applied the prototypes to perform color imaging of red blood cells (RBCs) infected with Plasmodium falciparum, a particularly harmful type of malaria parasites and one of the major causes of death in the developing world.

Stereoscopic optofluidic on-chip microscope

We demonstrate an optofluidic microscopy scheme which can acquire stereo images, utilizing different angles of illumination for projection imaging with our sub-pixel resolving optofluidic microscope.

Color-capable sub-pixel resolving optofluidic microscope for on-chip cell imaging

We report on the implementation of a color-capable sub-pixel resolving optofluidic microscope based on the pixel super-resolution algorithm and sequential RGB illumination, for low-cost on-chip color imaging of biological samples with sub-cellular resolution.

Subpixel resolving optofluidic microscope based on super resolution algorithm

We report the implementation of a fully on-chip, lensless, sub-pixel resolving optofluidic microscope (SROFM) based on the super resolution algorithm. The device utilizes microfluidic flow to deliver specimens directly across a complementary metal oxide semiconductor (CMOS) sensor to generate a sequence of low-resolution (LR) projection images, where resolution is limited by the sensors pixel size. This image sequence is then processed with a pixel super-resolution algorithm to reconstruct a single high resolution (HR) image, where features beyond the Nyquist rate of the LR images are resolved. We demonstrate the devices capabilities by imaging red blood cell, microspheres, protist Euglena gracilis, and Entamoeba invadens cysts with sub-cellular resolution. We also demonstrate the capability of SROFM for malaria infected red blood cell diagnostics.

Boosting detection sensitivity by using a surface-wave-enabled darkfield aperture (SWEDA)

The on-chip detection of a weak optical signal in biological experiments can easily be complicated by the presence of an overwhelming background signal, and as such, pre-detection background suppression is substantively important for weak signal detection. In this paper, we report a structure that can be directly incorporated onto optical sensors to accomplish background suppression prior to detection. This structure, termed surface-wave-enabled darkfield aperture (SWEDA), consists of a central sub-wavelength hole surrounded by concentric grooves that are milled onto a gold layer. Incoming light can be collected and converted into surface waves (SW) by the concentric grooves and then be recoupled into propagating light through the central hole. We show that the SW-assisted optical component and the direct transmission component of the central hole can cancel each other, resulting in near-zero transmission under uniform illumination (observed suppression factor of 1230). This structure can therefore be used to suppress a light fields bright background and allow sensitive detection of localized light field non-uniformity (observed image contrast enhancement of 27dB). We also show that under a coherent background illumination, a CMOS pixel patterned with the proposed structure achieves better SNR performance than an un-patterned single pixel.