Fabrication of flexible microlens arrays for parallel super-resolution imaging

Zhang, Tianyao; Pan, Li; Yu, Haibo; Wang, Feifei; Wang, Xiaoduo; Yang, Tianhang; Yang, Wenguang; Li, Wen J.; Wang, Yuechao; Liu, Lianqing

doi:10.1016/j.apsusc.2019.144375

Cited by 33 publications

(18 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In experiments, immersion of high-refractive-index microspheres may be required such as in biological imaging [8,29] or may offer the possibility of manipulating microspheres above the sample [30]. Working in immersion increases not only the resolving power, but also the imaging contrast.…”

Section: Resultsmentioning

confidence: 99%

Near- to Far-Field Coupling of Evanescent Waves by Glass Microspheres

et al. 2021

View full text Add to dashboard Cite

Through rigorous electromagnetic simulations, the natural coupling of high-spatial-frequency evanescent waves from the near field to the far field by dielectric microspheres is studied in air. The generation of whispering gallery modes inside the microspheres is shown independently of any resonance. In addition, the conversion mechanism of these evanescent waves into propagating waves is analysed. This latter point leads to key information that allows a better physical understanding of the super-resolution phenomenon in microsphere-assisted microscopy where sub-diffraction-limit revolving power is achieved.

show abstract

Section: Resultsmentioning

confidence: 99%

Near- to Far-Field Coupling of Evanescent Waves by Glass Microspheres

et al. 2021

View full text Add to dashboard Cite

show abstract

“…The FOV of a single sphere is smaller than the diameter of the sphere (

for

sphere); thus, there are unimaged portions between spheres. Although not demonstrated for SR-SHG, multiple spheres and image stitching have been used to reconstruct composite FOVs [ 43 – 45 ] and can be applied to our approach. Our approach retains the advantage of simplicity while offering increased speed of data acquisition relative to single-sphere approaches, and most importantly, is demonstrated for label-free laser-scanning nanoscopy (specifically SR-SHG).…”

Section: Resultsmentioning

confidence: 99%

Superresolved polarization-enhanced second-harmonic generation for direct imaging of nanoscale changes in collagen architecture

Johnson

Karvounis

Singh

et al. 2021

Optica

View full text Add to dashboard Cite

Superresolution (SR) optical microscopy has allowed the investigation of many biological structures below the diffraction limit; however, most of the techniques are hampered by the need for fluorescent labels. Nonlinear label-free techniques such as second-harmonic generation (SHG) provide structurally specific contrast without the addition of exogenous labels, allowing observation of unperturbed biological systems. We use the photonic nanojet (PNJ) phenomena to achieve SR-SHG. A resolution of with respect to the fundamental wavelength, that is, a -fold improvement over conventional or diffraction-limited SHG under the same imaging conditions is achieved. Crucially we find that the polarization properties of excitation are maintained in a PNJ. This is observed in experiment and simulations. This may have widespread implications to increase sensitivity by detection of polarization-resolved SHG by observing anisotropy in signals. These new, to the best of our knowledge, findings allowed us to visualize biological SHG-active structures such as collagen at an unprecedented and previously unresolvable spatial scale. Moreover, we demonstrate that the use of an array of self-assembled high-index spheres overcomes the issue of a limited field of view for such a method, allowing PNJ-assisted SR-SHG to be used over a large area. Dysregulation of collagen at the nanoscale occurs in many diseases and is an underlying cause in diseases such as lung fibrosis. Here we demonstrate that pSR-SHG allows unprecedented observation of changes at the nanoscale that are invisible by conventional diffraction-limited SHG imaging. The ability to nondestructively image SHG-active biological structures without labels at the nanoscale with a relatively simple optical method heralds the promise of a new tool to understand biological phenomena and drive drug discovery.

show abstract

“…With a 60 µm diameter sphere a focal position of z=70 µm was found to be the optimum to maximise resolution whilst avoiding overlap of images ( Figure 2). Although not demonstrated for SR-SHG, multiple spheres and image stitching has been used to reconstruct composite FOVs [31][32][33]. Our approach retains the advantage of simplicity whilst offering increased speed of data acquisition relative to single sphere approaches and most importantly is demonstrated for label-free laser-scanning nanoscopy (specifically SR-SHG).…”

Section: Resultsmentioning

confidence: 99%

Super-resolved polarisation-enhanced second harmonic generation for direct imaging of nanoscale changes in collagen architecture

Johnson

Karvounis

Singh

et al. 2020

Preprint

View full text Add to dashboard Cite

Super-resolution (SR) optical microscopy has allowed the investigation of many biological structures below the diffraction limit, however, most of the techniques are hampered by the need for fluorescent labels. Non-linear label-free techniques such as Second Harmonic Generation (SHG) provide structurally specific contrast without the addition of exogenous labels, allowing observation of unperturbed biological systems. Here we achieve super-resolution SHG (SR-SHG) for the first time. We use the photonic nanojet (PNJ) phenomena to achieve a resolution of ~λ/6 with respect to the fundamental wavelength, a ~2.7-fold improvement over diffraction-limited SHG under the same imaging conditions. Crucially we find that the polarisation properties of excitation are maintained in a PNJ allowing the resolution to be further enhanced by detection of polarisation-resolved SHG (p-SHG) by observing anisotropy in signals. These new findings allowed us to visualise biological SHG-active structures such as collagen at an unprecedented and previously unresolvable spatial scale. Moreover, we demonstrate that the use of an array of self-assembled high-index spheres overcomes the issue of a limited field of view for such a method, allowing PNJ-assisted SR-SHG to be used over a large area. Dysregulation of collagen at the nanoscale occurs in many diseases and is an underlying cause in diseases such as lung fibrosis. Here we are able to demonstrate that pSR-SHG allows unprecedented observation of changes at the nanoscale that are invisible by conventional diffraction-limited SHG imaging. The ability to non-destructively image SHG-active biological structures without labels at the nanoscale with a relatively simple optical method heralds the promise of a new tool to understand biological phenomena and drive drug discovery. List of abbreviationsSecond Harmonic Generation (SHG), Super-resolution (SR), Barium Titanate Glass (BTG), Photonic Nanojet (PNJ), Point Spread Function (PSF) Calculation of Polarisation anisotropyPolarisation anisotropy images were created using a home written Fiji macro in which the key steps are as follows: A difference image was generated by (Ipar -Iperp), this was divided by a total intensity image (Ipar + 2Iperp). The total intensity image was used to select the region of the image containing signal and for display all pixels outside of this region were set to 0. Only the regions containing signal were used for further anisotropy analysis. Collagen fibre analysisCollagen fibre analysis was performed using CT-FIRE V1.3. SHG intensity images were converted to 8bit format before being batch processed using default parameters. Four parameters were measured to describe fibre morphology, width, length, straightness and angle.

show abstract

Fabrication of flexible microlens arrays for parallel super-resolution imaging

Cited by 33 publications

References 43 publications

Near- to Far-Field Coupling of Evanescent Waves by Glass Microspheres

Near- to Far-Field Coupling of Evanescent Waves by Glass Microspheres

Superresolved polarization-enhanced second-harmonic generation for direct imaging of nanoscale changes in collagen architecture

Super-resolved polarisation-enhanced second harmonic generation for direct imaging of nanoscale changes in collagen architecture

Contact Info

Product

Resources

About