Abstract
Significant progress in characterization of nanoparticles and biomolecules was enabled by the development of advanced imaging equipment with extreme spatial-resolution and sensitivity. To perform some of these analyses outside of well-resourced laboratories, it is necessary to create robust and cost-effective alternatives to existing high-end laboratory-bound imaging and sensing equipment. Towards this aim, we have designed a holographic on-chip microscope operating at an ultraviolet illumination wavelength (UV) of 266 nm. The increased forward scattering from nanoscale objects at this short wavelength has enabled us to detect individual sub-30 nm nanoparticles over a large field-of-view of >16 mm2 using an on-chip imaging platform, where the sample is placed at ≤0.5 mm away from the active area of an opto-electronic sensor-array, without any lenses in between. The strong absorption of this UV wavelength by biomolecules including nucleic acids and proteins has further enabled high-contrast imaging of nanoscopic aggregates of biomolecules, e.g., of enzyme Cu/Zn-superoxide dismutase, abnormal aggregation of which is linked to amyotrophic lateral sclerosis (ALS) - a fatal neurodegenerative disease. This UV-based wide-field computational imaging platform could be valuable for numerous applications in biomedical sciences and environmental monitoring, including disease diagnostics, viral load measurements as well as air- and water-quality assessment.
Highlights
Resolution of an on-chip microscope to the diffraction limit by using pixel super-resolution approaches[24,25], e.g., by using an array of light sources to synthesize a high resolution image of the specimen from sub-pixel shifted versions of its hologram
Our holographic on-chip imaging platform consists of a 4th harmonic Nd:YAG laser generating 266 nm light, a custom-designed free-space light delivery system composed of multiple UV grade lenses and scanning galvo mirrors, and a CMOS image sensor chip (Fig. 1)
A uniform laser beam profile is generated using a spatial filter, by focusing the beam through a 25 μm pinhole and expanding it by a factor of 10 to have a large beam diameter covering the full area of the CMOS image sensor chip, which is equivalent to our imaging FOV (i.e., FOV = 16.45 mm2)
Summary
Resolution of an on-chip microscope to the diffraction limit by using pixel super-resolution approaches[24,25], e.g., by using an array of light sources to synthesize a high resolution image of the specimen from sub-pixel shifted versions of its hologram This platform was converted into a powerful nanoscale imaging device by self-assembly of polymer nano-droplets, or nanolenses, around the target particles to significantly enhance their optical signatures[26,27,28,29], enabling the detection of sub-40 nm particles over a FOV of >20–30 mm[2 27,28,29]. This unique UV-based wide-field computational imaging platform would be valuable for numerous applications in biomedical sciences and environmental monitoring, such as disease diagnostics, viral load measurements, as well as air- and water-quality monitoring
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
