Monolithically integrated microtube ring resonators for optofluidic sensing
Optical microtube resonators are monolithically integrated on photonic chips to demonstrate optofluidic functionality based on light-liquid interactions. The optofluidic structure is well-suited for potential biological/chemical sensing and analysis in a lab-in-a-tube system. Our experimental demonstration of monolithically integrated vertical ring resonators paves the way for optofluidics in three-dimensionally integrated photonic chips.
On-chip integration of rolled-up ring resonators as label-free optofluidic sensors
The advances we have made in engineering of tubular optical sensors and their on-chip integration allows us to fabricate rolled-up optofluidic ring resonators (RU-OFRRs) based on glass (SiO2) material with high quality factors fully integrated on-chip. The microfluidic integration of several RU-OFRRs on one chip is solved by enclosing the microtubes with a patterned robust SU-8 polymeric matrix. A viewport on each microtube enables exact excitation and monitoring of whispering gallery modes with a photoluminescence spectroscopy system under constant ambient conditions, while exchanging the content of the RU-OFRR with liquids of different refractive indices. The sensitivity of the integrated RU-OFRR, which is the response of the modes to the change in refractive index of the liquid, is up to 880 nm/refractive index units (RIU).
A lab-in-a-tube device comprises numerous ultracompact components in a single tube which can be developed using rolled-up technology. A single device, being one of thousands in the on-chip system, would be independently capable of stimulating, monitoring and investigating individual organisms.
Tubular optofluidic sensors for enhanced refractive index sensing
Optofluidic microcavities from rolled-up ring resonators with subwavelength wall thicknesses have been fabricated with excellent sensing function. The positions of resonant modes shift significantly when light emission was measured in different surrounding liquids, and thus the sensitivity can be calculated based on experimental observation. A maximum sensitivity of 425 nm/refractive index unit is currently achieved, which is caused by the pronounced propagation of the evanescent field in the surrounding media due to the subwavelength wall thickness design of the sensor. Our optofluidic sensors show high potential for lab-on-a-chip applications, e.g. real-time bio-analytic systems.
Glucose detection on the femtoliter scale
We use Si/SiO microtubes as optofluidic components to sense glucose concentrations in water. The Si/SiO microtubes are fully integrative on a single chip and allow analysis of fluid volumes in the range of femtoliters. Our technology allows monolithic integration of high speed Si nanoelectronics with lab-on-chip technologies.