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Ian M White

Publications and source records attributed to Ian M White.

3 recordsLinked to original sources

Thermal characterization of liquid core optical ring resonator sensors.

The liquid core optical ring resonator (LCORR) has recently shown promise as a high-sensitivity label-free lab-on-a-chip biological-chemical sensor. We investigate experimentally and theoretically the temperature dependence of the LCORR to establish a noise baseline, which will enable us to implement a temperature stabilization mechanism to reduce the thermally induced noise and to improve the sensor detection limit. Our studies involve analysis of the thermo-optic and thermomechanical effects of fused silica and aluminosilicate glass as they impact LCORR performance. Both thick-walled and thin-walled LCORRs are investigated to elucidate the contribution of water in the core to the thermal response of the LCORRs. Theoretical calculations based on Mie theory are used to verify the experimental observations.

Biosensing Techniques↗

Liquid-core optical ring-resonator sensors.

We have demonstrated a novel sensor architecture based on a liquid-core optical ring-resonator (LCORR) in which a fused silica capillary is utilized to carry the aqueous sample and to act as the ring resonator. The wall thickness of the LCORR is controlled to a few micrometers to expose the whispering gallery mode to the aqueous core. Optical characterization with a water-ethanol mixture shows that the spectral sensitivity of the LCORR sensor is approximately 2.6 nm per refractive index unit. A model based on Mie theory is established to explain the experimental results. The LCORR takes advantage of the high sensitivity, small footprint, and low sample consumption with the ring resonator, as well as the efficient fluidic sample delivery with the capillary, and will open an avenue to future multiplexed sensor array development.

Equipment Design↗

Subfemtomole detection of small molecules with microsphere sensors.

We investigated the feasibility of using a silica microsphere sensor for detection of small molecules. Using the silica molecules (60 Da) at the sphere's surface as a model system, we measured the spectral shifts in the whispering-gallery modes (WGMs) when the sphere size was decreased by a hydrofluoric acid (HF) solution. The results demonstrate that our sensor is capable of detecting a 4 pm (or 0.01 layer of silica) decrease in sphere radius, corresponding to a change of 0.4 fmol silica molecule. These results suggest that small molecules can be detected in trace quantities at the surface of an optical microsphere sensor.

Algorithms↗