Biomedical subjects

Jaeyoun Kim

Publications and source records attributed to Jaeyoun Kim.

5 recordsLinked to original sources

PubMed2006

Biologically inspired artificial compound eyes.

This work presents the fabrication of biologically inspired artificial compound eyes. The artificial ommatidium, like that of an insect's compound eyes, consists of a refractive polymer microlens, a light-guiding polymer cone, and a self-aligned waveguide to collect light with a small angular acceptance. The ommatidia are omnidirectionally arranged along a hemispherical polymer dome such that they provide a wide field of view similar to that of a natural compound eye. The spherical configuration of the microlenses is accomplished by reconfigurable microtemplating, that is, polymer replication using the deformed elastomer membrane with microlens patterns. The formation of polymer waveguides self-aligned with microlenses is also realized by a self-writing process in a photosensitive polymer resin. The angular acceptance is directly measured by three-dimensional optical sectioning with a confocal microscope, and the detailed optical characteristics are studied in comparison with a natural compound eye.

Animals↗

PubMed2005

Optofluidic control using photothermal nanoparticles.

Photothermal metallic nanoparticles have attracted significant attention owing to their energy-conversion properties. Here, we introduce an optofluidic application based on a direct optical-to-hydrodynamic energy conversion using suspended photothermal nanoparticles near the liquid-air interface. Using light beams with submilliwatt power, we can drive and guide liquid flow in microfluidic channels to transport biomolecules and living cells at controlled speeds and directions. Previously, a variety of methods for controlling microscale liquid flow have been developed owing to the increasing interest for microfluidics-based biochemical analysis systems. However, our method dispenses with the need for complex pump and valve devices, surface chemistry and electrode patterning, or any other further effort towards substrate fabrication. Instead, our optofluidic control method will allow the fabrication of all-optical large-scale integrated microfluidic circuits for biomolecular and cellular processing without any physical valve or mechanical pumping device.

Electrochemistry↗

PubMed2005

Artificial ommatidia by self-aligned microlenses and waveguides.

We report the fabrication of artificial ommatidia, the imaging units of insects' compound eyes, by use of polymer integrated optics. These biomimetic structures are obtained by configuring microlenses to play dual roles for self-writing of waveguides (during the fabrication) and collection of light (during the operation). The artificial ommatidium, consisting of a microlens, a spacer, and a waveguide, directly resembles the structure of its biological counterpart. Optical characterizations reveal single-peak angular sensitivity with a +/- 0.75 degrees acceptance angle that is comparable to those found in nature. Using geometric and physical optics, we also investigate the relationship between angular sensitivity and the geometry of artificial ommatidia.

Animals↗

PubMed2005

Nanophotonic crescent moon structures with sharp edge for ultrasensitive biomolecular detection by local electromagnetic field enhancement effect.

We present novel gold nanophotonic crescent moon structures with a sub-10 nm sharp edge, which can enhance local electromagnetic field at the edge area. The formation of unconventional nanophotonic crescent moon structure is accomplished by using a sacrificial nanosphere template and conventional thin film deposition method, which allows an effective batch nanofabrication and precise controls of nanostructure shapes. Unique multiple scattering peaks are observed in a single gold nanocrescent moon with dark-field white light illumination. A 785 nm near-infrared (NIR) diode laser was used as the excitation source to induce the amplified scattering field on the sharp edge of the single gold nanocrescent moon. The Raman scattering spectrum of Rhodamine 6G molecules adsorbed on the single gold nanocrescent moon are characterized, and the Raman enhancement factor of single gold nanocrescent moon is estimated larger than 10(10), which suggests the potential applications of gold nanocrescent moons in ultrasensitive biomolecular detection and cellular imaging using surface enhanced Raman spectroscopy.

Electromagnetic Fields↗

PubMed2004

Design and fabrication of a glass waveguide optical add-drop multiplexer by use of an amorphous-silicon overlay distributed Bragg reflector.

We report the fabrication of a distributed Bragg reflector (DBR) on a silver ion-exchanged glass waveguide with a patterned overlay of sputter-deposited amorphous silicon (a-Si). Using this high-refractive-index overlay DBR technology, we demonstrate a fully functional glass-integrated optic add-drop multiplexer (OADM). The OADM consists of a Mach-Zehnder interferometer (MZI) containing overlay DBR gratings in both arms. The design, fabrication, and characterization procedures of the sputter-deposited a-Si overlay DBR and the ion-exchanged glass waveguide MZI are discussed in detail. The completed 3-cm-long OADM exhibited a 24-dB transmission dip with a 3-dB bandwidth of 0.5 nm. The 1-cm-long a-Si overlay DBR induced an additional attenuation of 1.2 dB. A simplified method for overlay DBR fabrication that utilizes a lift-off technique is also proposed and demonstrated.

Journal Article↗