Yuze Sun

• University of Michigan

Enzyme-linked immunosorbent assay (ELISA) is a powerful method for biomolecular analysis. The traditional ELISA employing light intensity as the sensing signal often encounters large background arising from non-specific bindings, material autofluorescence and leakage of excitation light, which deteriorates its detection limit and dynamic range. Her...

We have applied self-assembled DNA tetrahedral nanostructures for the precise and tunable control of the gain in an optofluidic fluorescence resonance energy transfer (FRET) laser. By adjusting the ratio of the donor and the acceptor attached to the tetrahedral vertices, 3.8 times reduction in the lasing threshold and 28-fold enhancement in the las...

Using self-assembled DNA tetrahedron, we were able to precisely control the gain in optofluidic FRET lasers. 3.8 times reduction in the lasing threshold and 28-fold enhancement in the lasing efficiency were demonstrated.

The authors demonstrate a bio-inspired optofluidic laser with luciferin, a class of light-emitting compounds synthesized by many different organisms, as the gain medium. The laser characteristics under various conditions such as solution pH value and luciferin concentration are investigated. The authors demonstrate an optofluidic fluorescence reson...

We achieved optofluidic protein lasing using genetically encoded fluorescent protein FRET pairs linked by length-tunable peptides. Up to 25-fold reduction in the donor laser emission was observed when the donor and the acceptor were brought to close proximity, as compared to only 17% reduction in the donor emission using the conventional FRET detec...

We achieved optofluidic FRET lasers using genetically encoded fluorescent protein pairs linked by length-tunable peptides. 10-fold enhancement in the FRET sensing signal was demonstrated with the optofluidic FRET laser compared to the conventional FRET detection.

The paper highlights the recent research progress in the thin-walled capillary optofluidic ring resonator and nanohole array capillary sensing platforms developed in our lab. Sensing performance in both gas detection and biomolecular detection is presented.

We report the progress in developing optofluidic lasers to detect DNA mutations with unprecedented specificity. Rapid and direct differentiation between the target DNA and its point mutations is demonstrated using molecular beacons and intercalating dyes.

Laser precision: A highly sensitive technique based on laser emission for differentiating a target DNA strand from strands that contain single base mismatches has been developed. Laser emission is used to amplify the small difference in signals that are generated by the different strands after hybridization with a molecular beacon (MB, see picture)...

We report the progress of optofluidic lasers in the field of intra-cavity biosensing. Intra-cavity DNA detection is demonstrated with high differentiation between complementary sequence and single-base-mismatched sequence.

Optofluidic ring resonator lasers based on micro-bubbles filled with liquid gain medium are demonstrated. Due to the sub-micron wall thickness of the micro-bubble, significant amount of the electric field resides inside the liquid. Consequently, micro-bubbles mimic the droplets in air that have 3-dimensional optical confinement, extremely high Q-fa...

We report rapid, sensitive, and direct detection of 2,4-dinitrotoluene (DNT) vapor using tailored gold nanoparticles (Au-NPs) as the SERS substrate. The Au-NPs were synthesized using the UV-assisted photo-chemical reduction method and subsequently formed a monolayer on the glass slide through polymer-mediated self-assembly. The SERS substrate such...

Optofluidic ring resonator microlasers in conjunction with molecular beacons are used for intracavity detection of DNA single-nucleotide polymorphism. A discrimination ratio of 100 is achieved between the target DNA and single-base-mismatched DNA. OCIS codes: (300.6360) Spectroscopy, laser; (140.2050) Dye lasers; (280.1415) Biological sensing and s...

Surface enhanced Raman scattering (SERS) amplifies the small Raman scattering cross section of molecules toward distinguishable signal. It has been advanced into an influential label-free nondestructive method to measure vibrational fingerprints of molecular structures directly. We report here the demonstration of vapor detection of 2,4-dinitrotolu...

Single mode lasing from the polydimethylsiloxane based on-chip coupled optofluidic ring resonator (OFRR) with the lasing threshold of a few μJ/mm2 is demonstrated using the Vernier effect. The single mode operation is highly stable even at high pump energy densities. The effect of the OFRR size and coupling strength on the single mode emission is i...

Glass capillary and PDMS chip based optofluidic ring resonator lasers, along with their properties such as Q-factor, lasing threshold, out-coupling, and single-mode lasing, will be overviewed. Possible applications and future research directions will be discussed. Optofluidic lasers have attracted tremendous research interest in recent few years. T...

We theoretically analyze the ability of 3-dimensionally confined optofluidic ring resonators (OFRRs) for detection of a single nanoparticle in water and in air. The OFRR is based on a glass capillary, on which bottle-shaped and bubble-shaped ring resonators can form. The spectral position of the whispering gallery mode in the OFRR shifts when a nan...

We theoretically analyze the ability of 3-dimensionally confined optofluidic ring resonators (OFRRs) for detection of a single nanoparticle in water and in air. The OFRR is based on a glass capillary, on which bottle-shaped and bubble-shaped ring resonators can form. The spectral position of the whispering gallery mode in the OFRR shifts when a nan...

In this presentation various ring resonator structures will first be introduced, followed by their applications in biological and chemical sensing in aqueous and gas environment. Finally, future research and development directions will be discussed.

In the past few years optical ring resonators have emerged as a new sensing technology for highly sensitive detection of analytes in liquid or gas. This article introduces the ring resonator sensing principle, describes various ring resonator sensor designs, reviews the current state of the field, and presents an outlook of possible applications an...

Optofluidic dye lasers hold great promise for adaptive photonic devices, compact and wavelength-tunable light sources, and micro total analysis systems. To date, however, nearly all those lasers are directly excited by tuning the pump laser into the gain medium absorption band. Here we demonstrate bioinspired optofluidic dye lasers excited by FRET,...

We developed and characterized a Fabry-Pérot (FP) sensor module based micro gas chromatography (microGC) detector for multipoint on-column detection. The FP sensor was fabricated by depositing a thin layer of metal and a layer of gas-sensitive polymer consecutively on the endface of an optical fiber, which formed the FP cavity. Light partially refl...

We demonstrate the rapid detection of explosive vapors based on a fiber-based optical Fabry-Pérot (FP) gas sensor. The sensing probe of the FP sensor is composed of a thin metal layer and a vapor-sensitive polymer layer that are deposited sequentially on a cleaved fiber endface to form an FP cavity. The interference spectrum generated from the ref...

We overview the recent progress on optofluidic ring resonator (OFRR) dye lasers developed in our research group. The fluidics and laser cavity design can be divided into three categories: capillary optofluidic ring resonator (COFRR), integrated cylindrical optofluidic ring resonator (ICOFRR), and coupled optofluidic ring resonator (CpOFRR). The COF...

A versatile, compact, and sensitive fiber-based optical Fabry-Pérot (FP) gas sensor is reported in this paper. The sensor probe is composed of a silver layer and a vapor-sensitive polymer layer that are deposited on the cleaved fiber endface to form an FP cavity sequentially. The interference spectrum generated from the reflected light at the silve...

We report the development of optofluidic ring resonator (OFRR) dye laser through the fluorescence resonance energy transfer (FRET) between the donor molecule labeled on an oligonucleotide and the acceptor molecule labeled on a complementary oligonucleotide. The OFRR is a thin-walled fused silica capillary with a diameter around 80 mum and a wall th...

We demonstrated a novel tandem-column micro-gas chromatography (microGC) based on optofluidic ring resonator (OFRR). The OFRR is a thin-walled fused silica capillary whose interior surface is coated with a polymeric stationary phase. The circular cross section of the OFRR forms the micro-ring resonator and supports whispering gallery modes (WGMs)....

We demonstrated rapid 2,4-dinitrotoluene (DNT) vapor detection at room temperature based on an optofluidic ring resonator (OFRR) sensor. With the unique on-column separation and detection features of OFRR vapor sensors, DNT can be identified from other interferences coexisting in the analyte sample mixture, which is especially useful in the detecti...

The optofluidic ring resonator (OFRR) is a novel gas sensing technology platform. In an OFRR gas sensor, the OFRR interior surface is coated with a layer of vapor-sensitive polymer. The interaction between the polymer and the gas molecules flowing through the OFRR results in a change in polymer refractive index and thickness, which can be detected...

We discuss versatile, miniaturized optofluidic ring resonator (OFRR) dye lasers that can be operated regardless of the refractive index of the liquid. The OFRR is a piece of a thin-walled fused silica capillary that integrates the photonic ring resonator with microfluidics. In an OFRR dye laser, the active lasing materials (such as dyes) are passed...

The authors demonstrate the single mode dye laser from a coupled optofluidic ring resonator that consists of a cylindrical ring resonator fused onto the inner surface of a thin-walled capillary ring resonator. The whispering gallery modes in each ring resonator interact strongly and utilize the Vernier effect to generate single mode laser emission....

We develop a novel chemical vapor sensing platform based on optofluidic ring resonator (OFRR) for rapid and on-column detection and analysis of a wide range of chemical vapors. The OFRR is a thin-walled fused-silica capillary with a diameter of ~100 mum and a few centimeters in length. The circular cross-section of the OFRR defines a ring resonator...

We demonstrate a robust optofluidic dye laser that integrates fluidics with a high Q-factor ring resonator. In this optofluidic laser the ring resonator is formed by an optical fiber fused on the inner surface of a glass capillary serving as a fluidic channel. Laser oscillation is achieved with a threshold of 7 μ J ∕ mm 2 per pulse. Furthermore, th...

The authors develop optofluidic coupled ring resonator (OCRR) system in which one of the ring resonators serves as a microfluidic channel. Highly sensitive tuning of the OCRR is demonstrated by making small changes in the refractive index of the fluid. A refractometric sensing scheme using the OCRR is proposed and demonstrated, allowing for measuri...

We develop a versatile, compact, and sensitive fiber-based optical Fabry-Pérot (FP) gas sensor. The sensor probe is composed of a silver layer and a vapor-sensitive polymer layer that are sequentially deposited on the cleaved fiber endface, thus forming an FP cavity. The interference spectrum resulting from the reflected light at the silver-polymer...

In this work we present a method for creating an integrated optofluidic ring resonator (OFRR) laser system by embedding it in a low index polymer, polydimethylsiloxane (PDMS). Packaging the OFRR inside PDIVIS enhances portability, mechanical stability, and the ability to connect it to chip-based microfluidics. The OFRR retains high Q-factors even i...

This article reviews the recent progress in optical biosensors that use the label-free detection protocol, in which biomolecules are unlabeled or unmodified, and are detected in their natural forms. In particular, it will focus on the optical biosensors that utilize the refractive index change as the sensing transduction signal. Various optical lab...

Opto-fluidic ring resonator (OFRR) dye lasers are embedded in low index polydimethylsiloxane (PDMS) to achieve enhanced portability, mechanical stability, and potential integration with conventional soft lithography based microfluidics for development of micro total analysis systems. The OFRR retains high Q-factors (>10⁶) and exhibits low lasing th...

We carry out simulations based on a four-layer Mie model to systematically analyze the sensing performance of ring resonator chemical vapor sensors. Two sensor configurations are investigated, in which a polymer layer is coated on either interior or exterior surface of a fused silica cylindrical ring resonator. Upon the interaction of the polymer a...

We develop rapid chemical-vapor sensors based on optofluidic ring resonators (OFRRs). The OFRR is a glass capillary whose circular wall supports the circulating waveguide modes (WGMs). The OFRR inner surface is coated with a vapor-sensitive polymer. The analyte and polymer interaction causes the polymer refractive index to change, which is detected...

We developed a novel on-column micro gas chromatography (microGC) detector using capillary based optical ring resonators (CBORRs). The CBORR is a thin-walled fused silica capillary with an inner diameter ranging from a few tens to a few hundreds of micrometers. The interior surface of the CBORR is coated with a layer of stationary phase for gas sep...

Optical ring resonators have been investigated for a number of interesting devices, including dye lasers and sensors. However, in general, these devices can only operate on liquid samples with a low refractive index (RI) because the whispering gallery modes (WGMs) are bound in the resonator through total internal reflection at the resonator/sample...

We develop rapid chemical vapor sensors and micro gas chromatography (μGC) analyzers based on the optofluidic ring resonator (OFRR). An OFRR is a micro-sized thin-walled glass capillary; the circular cross-section of the capillary acts as an optical ring resonator while the whispering gallery modes or circulating waveguide modes (WGMs) supported by...

A versatile waveguide-coupled optofluidic device using the liquid core optical ring resonator (LCORR) that can be operated with liquid of any refractive index (RI) is theoretically analyzed and experimentally demonstrated. The results confirm the confinement of resonant modes for all sample RIs, and reveal that confined modes in a high-RI core are...

We develop a versatile integrated opto-fluidic ring resonator (OFRR) dye laser that can be operated regardless of the refractive index (RI) of the liquid. The OFRR is a micro-sized glass capillary with a wall thickness of a few micrometers. When the liquid in the core has an RI lower than that of the capillary wall (n=1.45), the capillary circular...