scholarly journals Operando monitoring transition dynamics of responsive polymer using optofluidic microcavities

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Da-Quan Yang ◽  
Jin-hui Chen ◽  
Qi-Tao Cao ◽  
Bing Duan ◽  
Hao-Jing Chen ◽  
...  
Keyword(s):  
Phase Transition ◽  
Refractive Index ◽  
Complex Dynamics ◽  
Refractive Index Change ◽  
Transition Process ◽  
Fast Response ◽  
Transition Dynamics ◽  
Biochemical Processes ◽  
Optical Microcavities ◽  
Irreversible Phase Transitions

AbstractOptical microcavities have become an attractive platform for precision measurement with merits of ultrahigh sensitivity, miniature footprint and fast response. Despite the achievements of ultrasensitive detection, optical microcavities still face significant challenges in the measurement of biochemical and physical processes with complex dynamics, especially when multiple effects are present. Here we demonstrate operando monitoring of the transition dynamics of a phase-change material via a self-referencing optofluidic microcavity. We use a pair of cavity modes to precisely decouple the refractive index and temperature information of the analyte during the phase-transition process. Through real-time measurements, we reveal the detailed hysteresis behaviors of refractive index during the irreversible phase transitions between hydrophilic and hydrophobic states. We further extract the phase-transition threshold by analyzing the steady-state refractive index change at various power levels. Our technology could be further extended to other materials and provide great opportunities for exploring on-demand dynamic biochemical processes.

scholarly journals Photochemical On–Off Switching of One-Dimensional Photonic Crystals Consisting of Azo-Functionalized Liquid Crystal Polymer and Polyvinyl Alcohol

Crystals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 610 ◽  
Author(s):  
Sunnam Kim ◽  
Seiji Kurihara
Keyword(s):  
Phase Transition ◽  
Refractive Index ◽  
Liquid Crystal ◽  
Photonic Crystals ◽  
Polyvinyl Alcohol ◽  
Refractive Index Change ◽  
Liquid Crystal Polymer ◽  
Index Change ◽  
One Dimensional ◽  
Crystal Polymer

One-dimensional (1D) photonic crystals (PCs) are prepared from multi-bilayered films stacked with alternating azo-functionalized liquid crystal polymer (PAz) films and polyvinyl alcohol (PVA) films. Reflection with a wavelength that depends on the thickness of the films is observed, and the reflection can be turned on and off by switching between the two states, based on whether there is a difference in the refractive index between the two films. The refractive index change of PAz can be photochemically caused by a phase transition, based on the alignment states of the liquid crystal (LC). In this review, we focused on an effective photo-induced on–off switching approach in 1D PCs using LC properties and described the basic optical and chemical principles, the experimental results, and further optimizations.

scholarly journals Critical angle reflection imaging for quantification of molecular interactions on glass surface

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Guangzhong Ma ◽  
Runli Liang ◽  
Zijian Wan ◽  
Shaopeng Wang
Keyword(s):  
Refractive Index ◽  
Small Molecule ◽  
Molecular Interactions ◽  
Glass Surface ◽  
Critical Angle ◽  
Dynamic Range ◽  
Refractive Index Change ◽  
Label Free ◽  
Index Change ◽  
Sensing Range

AbstractQuantification of molecular interactions on a surface is typically achieved via label-free techniques such as surface plasmon resonance (SPR). The sensitivity of SPR originates from the characteristic that the SPR angle is sensitive to the surface refractive index change. Analogously, in another interfacial optical phenomenon, total internal reflection, the critical angle is also refractive index dependent. Therefore, surface refractive index change can also be quantified by measuring the reflectivity near the critical angle. Based on this concept, we develop a method called critical angle reflection (CAR) imaging to quantify molecular interactions on glass surface. CAR imaging can be performed on SPR imaging setups. Through a side-by-side comparison, we show that CAR is capable of most molecular interaction measurements that SPR performs, including proteins, nucleic acids and cell-based detections. In addition, we show that CAR can detect small molecule bindings and intracellular signals beyond SPR sensing range. CAR exhibits several distinct characteristics, including tunable sensitivity and dynamic range, deeper vertical sensing range, fluorescence compatibility, broader wavelength and polarization of light selection, and glass surface chemistry. We anticipate CAR can expand SPR′s capability in small molecule detection, whole cell-based detection, simultaneous fluorescence imaging, and broader conjugation chemistry.

scholarly journals Electrically Induced Liquid–Liquid Phase Transition in a Floating Water Bridge Identified by Refractive Index Variations

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 602
Author(s):  
Elmar C. Fuchs ◽  
Jakob Woisetschläger ◽  
Adam D. Wexler ◽  
Rene Pecnik ◽  
Giuseppe Vitiello
Keyword(s):  
Phase Transition ◽  
Refractive Index ◽  
Liquid Phase ◽  
Pure Water ◽  
Resonance Effect ◽  
Water Bridge ◽  
Liquid Phase Transition ◽  
Light Passing ◽  
Floating Water Bridge ◽  
Set Up

A horizontal electrohydrodynamic (EHD) liquid bridge (also known as a “floating water bridge”) is a phenomenon that forms when high voltage DC (kV·cm−1) is applied to pure water in two separate beakers. The bridge, a free-floating connection between the beakers, acts as a cylindrical lens and refracts light. Using an interferometric set-up with a line pattern placed in the background of the bridge, the light passing through is split into a horizontally and a vertically polarized component which are both projected into the image space in front of the bridge with a small vertical offset (shear). Apart from a 100 Hz waviness due to a resonance effect between the power supply and vortical structures at the onset of the bridge, spikes with an increased refractive index moving through the bridge were observed. These spikes can be explained by an electrically induced liquid–liquid phase transition in which the vibrational modes of the water molecules couple coherently.

scholarly journals Mechanism research on crack propagation in coal induced by CO2 phase-transition fracturing under different lateral compression coefficients

2021 ◽  
pp. 014459872110153
Author(s):  
Qingsong Li ◽  
Jinlei Fu ◽  
Xianwei Heng ◽  
Xiaoqian Xu ◽  
Shu Ma
Keyword(s):  
Phase Transition ◽  
Crack Propagation ◽  
Initial Stress ◽  
Main Crack ◽  
Transition Process ◽  
Simulation Software ◽  
Lateral Compression ◽  
Monitoring Point ◽  
Micro Cracks ◽  
Fractured Coal

To study crack propagation around the fracture hole in the coal body induced by high-pressure CO2 gas produced by CO2 phase transition fracturing, the mechanism of permeability enhancement of fractured coal induced by liquid CO2 phase transition fracturing was studied from two aspects, the process of coal gas displacement by competitive adsorption and physical characteristics of fractured coal induced by phase transition. Crack propagation pattern in coal under different lateral coefficients was explored by using discrete-element numerical simulation software. Distribution characteristics of hoop stress of fractured coal were analyzed through theoretical calculation. The results show that: (1) Micro-cracks in damaged coal body generated during phase transition process are mainly crack_tension type, which are formed by the composite action of tension and compression. The crack propagation is the result of the continuous release of compressive stress from concentrated area to the surrounding units. Micro-cracks are radially distributed in a pattern of “flame”. (2) The main crack formed above the fracture hole grows in the direction of vertical minimum initial stress, and the main crack formed below the fracture hole develops in the direction of horizontal initial stress. As the lateral compression coefficient increases, the extension distance of the second crack will not change after reducing to a certain length. (3) As the distance from the fracture hole increases, the peak compression loaded at the monitoring point decays, and the loop stress in the cracked coal is distributed in a pattern of “peanut”. It provides practical methods and ideas for studying the macroscopic and microscopic development of cracks, as well as theoretical support for the on-site hole layout.

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