15 Super-Resolution Imaging and Microscopy by Dielectric …
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into polystyrene matrix. A nanoparticle-hybrid suspension polymerisation approach
was developed for such purpose; high-quality microspheres ZrO 2 /PS hybrid microspheres have been synthesized with highly controllability in shape and refractive
index (np = 1.590–1.685) [116]. Figure 15.18 shows nanohybrid particle-lens (a–d)
and its super-resolution imaging performance configured in a semi-immersed liquid
environment (e). Comparing (g) and (h), it is obvious that increasing the refractive
index of microspheres from 1.590 to 1.685 improve both the imaging resolution and
quality. A 60 nm resolution has been obtained in the wide-field imaging mode and
a 50 nm resolution in the confocal mode. The synthesis of hybrid microspheres is
feasible, easily repeatable and designable in shape, size and refractive index. Accordingly, the approach is quite general, and can be readily extended to prepare a series
of hybrid microspheres with various refractive index and optical transparency, by
changing the types of polymers and nanoparticles. The as-synthesized nanohybrid
colloidal microspheres can be used not only in optical nanoscope for super-resolution
imaging with visible frequency, but also in some potential fields of nanolithography,
optical memory storage, and optical nano-sensing.
15.5 Biological Superlens
Fabrication of superlenses is often complex and requires sophisticated engineering
processes. Clearly an easier model candidate, such as a naturally occurring superlens,
is highly desirable. Recently, Monks et al. reported a biological superlens provided
by nature: the minor ampullate spider silk spun from the Nephila spider [117]. This
natural biosuperlens can distinctly resolve 100 nm features under a conventional
white-light microscope with peak wavelength at 600 nm, obtaining a resolution of
λ/6 that is well beyond the classical limit.
Figure 15.19 shows Spider silk biological superlens and its imaging performance.
The used spider silk is from Nephila edulis spider, with diameter about 6.8 μm
(Fig. 15.19a). The spider silk was placed directly on top of the sample surface by
using a transparent cellulose-based tape. The gaps between silk and sample was filled
with IPA which improves imaging contrast. The silk lens collects the underlying nearfield object information and projects a magnified virtual image into a conventional
objective lens (100×, NA: 0.9, Fig. 15.19b). The spider silk magnifies objects about
2.1× times (Fig. 15.19c), allowing subdiffraction object to be seen. Blu-ray disc
with 100 nm features were clearly resolved by the spider silk (Fig. 15.19d), under
an angular beam incident at around 30°. Simulated intensity field in Fig. 15.19g
reveals how the samples was illuminated by the angular jet. In Fig. 15.19h, it was also
shown that the spider silk produced similar quality of super-resolution image as BTG
microspheres, despite the image was slightly rotated by approximately four degree
due to fibre direction is not parallel to grating direction (like case in d). This research
provides a solid foundation for the development of bio-superlens technology, and it is
the first expose of spider silk in this context. It is expected more biological superlenses
to be discovered. Indeed, interesting and important recent work by other researchers
397
into polystyrene matrix. A nanoparticle-hybrid suspension polymerisation approach
was developed for such purpose; high-quality microspheres ZrO 2 /PS hybrid microspheres have been synthesized with highly controllability in shape and refractive
index (np = 1.590–1.685) [116]. Figure 15.18 shows nanohybrid particle-lens (a–d)
and its super-resolution imaging performance configured in a semi-immersed liquid
environment (e). Comparing (g) and (h), it is obvious that increasing the refractive
index of microspheres from 1.590 to 1.685 improve both the imaging resolution and
quality. A 60 nm resolution has been obtained in the wide-field imaging mode and
a 50 nm resolution in the confocal mode. The synthesis of hybrid microspheres is
feasible, easily repeatable and designable in shape, size and refractive index. Accordingly, the approach is quite general, and can be readily extended to prepare a series
of hybrid microspheres with various refractive index and optical transparency, by
changing the types of polymers and nanoparticles. The as-synthesized nanohybrid
colloidal microspheres can be used not only in optical nanoscope for super-resolution
imaging with visible frequency, but also in some potential fields of nanolithography,
optical memory storage, and optical nano-sensing.
15.5 Biological Superlens
Fabrication of superlenses is often complex and requires sophisticated engineering
processes. Clearly an easier model candidate, such as a naturally occurring superlens,
is highly desirable. Recently, Monks et al. reported a biological superlens provided
by nature: the minor ampullate spider silk spun from the Nephila spider [117]. This
natural biosuperlens can distinctly resolve 100 nm features under a conventional
white-light microscope with peak wavelength at 600 nm, obtaining a resolution of
λ/6 that is well beyond the classical limit.
Figure 15.19 shows Spider silk biological superlens and its imaging performance.
The used spider silk is from Nephila edulis spider, with diameter about 6.8 μm
(Fig. 15.19a). The spider silk was placed directly on top of the sample surface by
using a transparent cellulose-based tape. The gaps between silk and sample was filled
with IPA which improves imaging contrast. The silk lens collects the underlying nearfield object information and projects a magnified virtual image into a conventional
objective lens (100×, NA: 0.9, Fig. 15.19b). The spider silk magnifies objects about
2.1× times (Fig. 15.19c), allowing subdiffraction object to be seen. Blu-ray disc
with 100 nm features were clearly resolved by the spider silk (Fig. 15.19d), under
an angular beam incident at around 30°. Simulated intensity field in Fig. 15.19g
reveals how the samples was illuminated by the angular jet. In Fig. 15.19h, it was also
shown that the spider silk produced similar quality of super-resolution image as BTG
microspheres, despite the image was slightly rotated by approximately four degree
due to fibre direction is not parallel to grating direction (like case in d). This research
provides a solid foundation for the development of bio-superlens technology, and it is
the first expose of spider silk in this context. It is expected more biological superlenses
to be discovered. Indeed, interesting and important recent work by other researchers