High-Quality Large-Magnification Polymer Lens from Needle Moving Technique and Thermal Assisted Moldless Fabrication Process.

The need of mobile microscope is escalating as well as the demand of high quality optical components in low price. We report here a novel needle moving technique to fabricate milli-size lens together with thermal assist moldless method. Our proposed protocol is able to create a high tensile strength structure of the lens and its base which is beneficial for exploiting in convertinga smart phone to be a digital microscope. We observe that no bubble trapped in a lens when this technique is performed which can overcome a challenge problem found in a typical dropping technique. We demonstrate the symmetry, smoothness and micron-scale resolution of the fabricated structure. This proposed technique is promising to serve as high quality control mass production without any expensive equipment required

Synthesis of PEGylated gold nanorods (Au NRs) as absorption nanoprobes for near-infrared optical imaging

In this contribution, we show that Au NRs functionalized with PEG molecules can be used as absorption nanoprobes for near-infrared imaging in live animals. We have found that the contrast signal of the in vivo image is dependent upon the transmission ability of the NIR light interacting with the different aspect ratios of Au NRs. Our study was focused on absorption in vivo imaging at 700 nm, which is within the transmission window of the skin. NIR absorption in vivo imaging was carried out by subcutaneous injection of mice with PEGylated Au NRs that have a LSPR around 700 nm. The formulation showed strong contrast signals under the tissues upon irradiation with NIR light. More importantly, our theoretical calculation suggested that the high contrast signals from the PEGylated Au NRs were generated via the NIR light absorption of the Au NRs within the tissue

A Lens geometry study.

<p>(a) Three-dimensional surface geometry of the fabricating lens, (b) demonstrating symmetry in both x and y axes.</p

A high tensile lens created by different needle position.

<p>(a) The needle moving technique with the depth h inside the polymer droplet creates a lens which has the radius R₂ and height H, whereas the typical dropping technique gives a lens with smaller radius R₁. (b) Experimental data shows that the ratio R₂to R₁ depends mainly on the depth h, when H, R₁ and D are controlled parameters.</p

An infrared photo of lens formation.

<p>(a) Heat transfer from the hot surface into the polymer during 8 seconds of the lens formation, obtained by heating the surface at 180°C, and 20 μl of polymer droplet. Numerical simulation of heat transfer using shows temperature distribution at (b) 0, (c) 2, and (d) 8 seconds during lens formation.</p

A relationship of lens focal length and fabricated temperature.

<p>Measured focal length depends on the surface temperature and the volume of the polymer. Upon temperature increasing, the focal length decreases.</p

An image quality testing.

<p>Line profile plots and images of a standard USAF 1951 pattern: (a) group 8–3 and (b) 8–4. The white dash lines indicate the region of obtaining the intensity data.</p

A mobile microscope.

<p>Optical photographs of (a) nauplius larvae and (b) aquatic nematodes taken by (c) an iPhone 4S attached with our PDMS lens with its base on the camera. Photographs of RGB pixels demonstrate field of view of (d) 50x and (e) 100x magnification of our preparing lens.</p

A needle moving technique.

<p>Schematic representation of (a) flat base formation using free fall drop of PDMS from a needle with distance Z_b away from a glass slide under thermal assisted at 200°C for 20 seconds, and (b) lens fabrication with high tensile strength between lens and its base generated by the proposed moving needle technique.</p