Deep learning enhanced NIR-Ⅱ volumetric imaging of whole mice vasculature

Fluorescence imaging through the second near-infrared window(NIR-Ⅱ,1000–1700 nm) allows in-depth imaging.However, current imaging systems use wide-field illumination and can only provide low-contrast 2D information, without depth resolution. Here, we systematically apply a light-sheet illumination, a time-gated detection, and a deep-learning algorithm to yield high-contrast high-resolution volumetric images. To achieve a large Fo V(field of view) and minimize the scattering effect, we generate a light sheet as thin as 100.5 μm with a Rayleigh length of 8 mm to yield an axial resolution of 220 μm. To further suppress the background, we time-gate to only detect long lifetime luminescence achieving a high contrast of up to 0.45 Icontrast. To enhance the resolution, we develop an algorithm based on profile protrusions detection and a deep neural network and distinguish vasculature from a low-contrast area of 0.07 Icontrast to resolve the 100μm small vessels. The system can rapidly scan a volume of view of 75 × 55 × 20 mm3and collect 750 images within 6mins. By adding a scattering-based modality to acquire the 3D surface profile of the mice skin, we reveal the whole volumetric vasculature network with clear depth resolution within more than 1 mm from the skin. High-contrast large-scale 3D animal imaging helps us expand a new dimension in NIR-Ⅱ imaging.

Sperm quality metrics were improved by a biomimetic microfluidic selection platform compared to swim-up methods

Sperm selection is an essential component of all assisted reproductive treatments(ARTs)and is by far the most neglected step in the ART workflow in regard to technological innovation.Conventional sperm selection methodologies typically produce a higher total number of sperm with variable motilities,morphologies,and levels of DNA integrity.Gold-standard techniques,including density gradient centrifugation(DGC)and swim-up(SU),have been shown to induce DNA fragmentation through introducing reactive oxygen species(ROS)during centrifugation.Here,we demonstrate a 3D printed,biologically inspired microfluidic sperm selection device(MSSP)that utilizes multiple methods to simulate a sperms journey toward selection.Sperm are first selected based on their motility and boundary-following behavior and then on their expression of apoptotic markers,yielding over 68%more motile sperm than that of previously reported methods with a lower incidence of DNA fragmentation and apoptosis.Sperm from the MsSP also demonstrated higher motile sperm recovery after cryopreservation than that of sU or neat semen.Experiments were conducted side-by-side against conventional SU methods using human semen(n=33)and showed over an 85%improvement in DNA integrity with an average 90%reduction in sperm apoptosis.These results that the platform is easy-to-use for sperm selection and mimics the biological function of the female reproductive tract during conception.

Polarized upconversion emission at metasurface

Leveraging the resonant modes of all-dielectric metasurfaces,specifically quasi-bound state in the continuum and Mie resonances,the precise orthogonal polarization control has been realized.

Frequency-domain diagonal extension imaging

The pixel size of a charge-coupled device(CCD)camera plays a major role in the image resolution,and the square pixels are attributed to the physical anisotropy of the sampling frequency.We synthesize the high sampling frequency directions from multiple frames acquired with different angles to enhance the resolution by 1.4×over conventional CCD orthogonal sampling.To directly demonstrate the improvement of frequency-domain diagonal extension(FDDE)microscopy,lens-free microscopy is used,as its resolution is dominantly determined by the pixel size.We demonstrate the resolution enhancement with a mouse skin histological specimen and a clinical blood smear sample.Further,FDDE is extended to lens-based photography with an ISO 12233 resolution target.This method paves a new way for enhancing the image resolution for a variety of imaging techniques in which the resolution is primarily limited by the sampling pixel size,for example,microscopy,photography,and spectroscopy.