A microfluidic chip for high resolution Raman imaging of biological cells

A microfluidic chip was designed, prepared and tested for integration with a confocal Raman imaging spectrometer with the specific purpose of enabling studies of individual biological cells. The design of the chip effectively overcomes the limitations arising from the high numerical aperture (NA) and short working distance objectives, which are necessary for high resolution imaging. The high confocal spatial resolution was achieved by a careful design of the geometry of the chip together with a thin, optically and Raman silent sealing window as the embedding medium for the channels. A leak-free microfluidic chip was obtained by surface plasma modification of polydimethylsiloxane (PDMS) and optimization of the liquid loading parameters. Raman images of biological cells, which were transported by flow into the microfluidic chip, are presented as an example of a Raman-microfluidics application. The broad band Raman spectra from −50 cm−1 to 3650 cm−1 were recorded in 1600 frequency intervals without any signal enhancement or sample labeling. Raman images were recorded in ∼400 seconds and they typically consisted of 64 × 64 pixels with a step size of 250 nm, thus containing ∼4 × 106 data points altogether

Microfluidic device for DNA amplification of single cancer cells isolated from whole blood by self-seeding microwells

Self-seeding microwell chips can sort single cells into 6400 wells based on cell size and their identity verified by immunofluorescence staining. Here, we developed a microfluidic device in which these single cells can be placed, lysed and their DNA amplified for further interrogation. Whole blood spiked with MCF7 tumor cells was passed through the microwell chips after leukocyte depletion and 37% of the MCF7 cells were identified by epithelial cell adhesion molecule (EpCAM) staining in the microwells. Identified single cells were punched into the reaction chamber of the microfluidic device and reagents for cell lysis and DNA amplification introduced sequentially by peristaltic pumping of micro-valves. On-chip lysis and amplification was performed in 8 parallel chambers yielding a 10000 fold amplification of DNA. Accessibility of the sample through the reaction chamber allowed for easy retrieval and interrogation of target-specific genes to characterize the tumor cells

Chiroptical effect induced by achiral structures for full dimensional manipulation of optical waves

The chiroptical effects are omnipresent throughout the universe and play a vital role in the sorting and detecting enantiomers in numerous applications like life sciences, pharmaceuticals, agrochemicals, food industry, etc. These chiroptical effects, along with polarization retention and full phase modulation, can have a significant potential for applications such as chiral imaging, anti-counterfeiting, and security. For strong chiroptical effects, all-dielectric metadevices offer a compact and efficient substitute to three-dimensional (3D) chiral metamaterials and flat plasmonic metadevices, which are prone to complex fabrication and ohmic losses, respectively. Here, we propose a unique metasurface based on the combination of achiral structures to achieve chiroptical effect with polarization retention and wavefront shaping. The proposed structure reflects the left hand circularly polarized (LHCP) light while preserving its handedness with complete absorption of the right hand circularly polarized (RHCP) and vice versa. Meanwhile, the structure provides full 2�� phase modulation designed by hydrogenated amorphous silicon (a-Si:H), which is a low-loss, CMOS (complementary metal-oxide-semiconductor) compatible material with fabrication ease. The spin-selective reflection with circular dichroism and full phase modulation of designed structure find application in integrated optics, quantum optics, detection, and chiral imaging. ? 2021 SPIE.11Nscopu