Theoretical Analysis of an Optical Accelerometer Based on Resonant Optical Tunneling Effect

Acceleration is a significant parameter for monitoring the status of a given objects. This paper presents a novel linear acceleration sensor that functions via a unique physical mechanism, the resonant optical tunneling effect (ROTE). The accelerometer consists of a fixed frame, two elastic cantilevers, and a major cylindrical mass comprised of a resonant cavity that is separated by two air tunneling gaps in the middle. The performance of the proposed sensor was analyzed with a simplified mathematical model, and simulated using finite element modeling. The simulation results showed that the optical Q factor and the sensitivity of the accelerometer reach up to 8.857 × 107 and 9 pm/g, respectively. The linear measurement range of the device is ±130 g. The work bandwidth obtained is located in 10–1500 Hz. The results of this study provide useful guidelines to improve measurement range and resolution of integrated optical acceleration sensors

Improvement of Q Value Based on Resonant Optical Tunneling Effect Microcavity

As a classical optical structure, optical resonator has been widely used in optical communication and optical sensing, and has always been a hot spot in optoelectronics research. Resonant optical tunneling effect microcavity, derived from frustrated total internal reflection, is a new type of optical microcavity. According to the Gansch formula, two methods were adopted to reduce the absorption of cavity (increase Qabs) and change the structural parameters to increase the Q value of the structure (increase Qstr). ROTE structure model was established, and by using the transfer matrix method, the reflection spectrum line and Q value of rote structure were evaluated. The simulation results show that by reducing the cavity absorption and adjusting system parameters (tunneling layer thickness, incident angle, etc), the total Q value of the resonant cavity of the ROTE structure is increased by about 105 times, and the Q value can be expected to reach 108. Compared with the traditional FP cavity structure (Q value is in the order of 103-104) and the current mainstream whispering gallery mode structure (Q value is in the order of 107-108), the ROTE structure resonator can reach the world-class level in the theoretical Q value, and also has the advantages of easy integration, simple process, high-stability, and low cost. This article paves the road for the preparation and further application of high-Q ROTE structure

A zero-flow microfluidics for long-term cell culture and detection

A zero-flow microfluidic design is proposed in this paper, which can be used for long-term cell culture and detection, especially for a lab-on-chip integrated with a biosensor. It consists of two parts: a main microchannel; and a circle microchamber. The Finite Element Method (FEM) was employed to predict the fluid transport properties for a minimum fluid flow disturbance. Some commonly used microfluidic structures were also analysed systematically to prove the designed structure. Then the designed microfluidics was fabricated. Based on the simulations and experiments, this design provides a continuous flow environment, with a relatively stable and low shear stress atmosphere, similar to a zero-flow environment. Furthermore, the nutrients maintaining cells’ normal growth can be taken into the chamber through the diffusion effect. It also proves that the microfluidics can realize long-term cell culture and detection. The application of the structure in the field of biological microelectromechenical systems (BioMEMS) will provide a research foundation for microfluidic technology

Research on the Construction of Tissue Engineering Epidermal Substitute Based on Collagen-Agarose

From the perspective of developing new tissue engineering epidermal substitutes, collagen and agarose were selected to construct a composite hydrogel to support the growth of epidermal cells. Collagen solution (2%) and agarose solution (2%) were used to investigate the morphology, physical and chemical properties and mechanical properties of the collagen-agarose composite hydrogels with collagen as a control. The biocompatibility of collagen-agarose composite hydrogel with human immortalized epidermal cells (HaCaT) was also examined. The results show that agarose improved the mechanical properties of collagen. The mechanical properties and biocompatibility of the scaffold were balanced when the content of collagen and agarose is 65% and 35%, respectively. The composite hydrogel based on collagen-agarose developed in this study is an ideal epidermal substitute for tissue engineering

Optofluidics Refractometers

Refractometry is a classic analytical method in analytical chemistry and biosensing. By integrating advanced micro- and nano-optical systems with well-developed microfluidics technology, optofluidics are shown to be a powerful, smart and universal platform for refractive index sensing applications. This paper reviews recent work on optofluidic refractometers based on different sensing mechanisms and structures (e.g., photonic crystal/photonic crystal fibers, waveguides, whisper gallery modes and surface plasmon resonance), and traces the performance enhancement due to the synergistic integration of optics and microfluidics. A brief discussion of future trends in optofluidic refractometers, namely volume sensing and resolution enhancement, are also offered

Synthesis of p-Co3O4/n-TiO2 Nanoparticles for Overall Water Splitting under Visible Light Irradiation

p-Co3O4/n-TiO2 nanoparticles (~400 nm) for photocatalysis were prepared via carbon assisted method and sol-gel method in this work. The paper also studied the application of visible light illuminated p-Co3O4/n-TiO2 nanocomposites cocatalyst to the overall pure water splitting into H2 and O2. In addition, the H2 evolution rate of the p-Co3O4/n-TiO2 nanocomposites is 25% higher than that of the pure Co3O4 nanoparticles. Besides, according to the results of the characterizations, the scheme of visible light photocatalytic water splitting is proposed, the Co3O4 of the nanocomposites is excited by visible light, and the photo-generated electrons and holes existing on the conduction band of Co3O4 and valence band of TiO2 have endowed the photocatalytic evolution of H2 and O2 with higher efficiency. The optimal evolution rate of H2 and O2 is 8.16 μmol/h·g and 4.0 μmol/h·g, respectively

Star-shape Electrode Dielectrophoresis Chip

In this paper, an effective method of enriching polystyrene (PS) microspheres on dielectrophoretic chip by negative dielectrophoretic force was proposed. A star-shaped microelectrode was designed and fabricated on a glass substrate by a lift-off process. Under the action of a high-frequency AC signal, the star-shaped microelectrode chip can provide a specific non-uniform electric field, which can produce negative dielectrophoretic force. The effects of amplitude and frequency of AC signal, conductivity and concentration of working solution on the enrichment of PS microspheres were investigated. The results show that when the voltage parameter of AC signal is 9 V and the frequency parameter is 1 MHz, the PS microspheres with low conductivity are enriched in the center of the electrode. With the aid of negative dielectrophoresis force, the concentration of PS microsphere suspension in the range of 0.33~2.08 amol/mL can form microsphere clusters. The results of this study have potential applications in molecular cell biology, pharmacology, and biochemistry

Au/CQDs‐TiO2 composite nanorod array film with simple preparation route and enhanced visible light response

Abstract This paper successfully prepared a unique titanium dioxide nanorod arrays nanocomposite doped with carbon quantum dots and gold nanoparticles as a high‐efficiency photocatalyst. Due to their enhanced electron–hole separation efficiency and strong light‐scattering effects, one‐dimensional nanostructured titanium dioxide nanorods were utilised as the basic material for photocatalysis. Furthermore, gold nanoparticles and carbon quantum dots modified on the surface of titanium dioxide nanorods were used as visible light absorbers and photosensitisers, respectively. As a result, a photocurrent of 14 mA·cm‐2 was achieved by Au/CQDs‐TiO2 nanorods composite in the photoelectrochemical measurements, which exceed five times that of pure titanium dioxide nanorods. The synergistic effect of gold nanoparticles and carbon quantum dots was demonstrated by several characterisation techniques. The proposed Au/CQDs‐TiO2 nanorods nanocomposite film developed by simple successive ionic layer adsorption and reaction and hydrothermal methods offers a practical solution for current environmental and energy issues

Cell Density Detector Based on Light Beam Focusing

Although the lab-on-a-chip system has been successfully applied in a wide variety of fields, the goal of achieving a cell counter with simple operation, low cost, and high accuracy still attracts continuous research efforts. In this paper, the authors explore a cell counter based on light beam focusing to measure the density of adherent cells. In this sensor, the light emitted from the optical fibers is collimated by the collimating lens formed in polydimethylsiloxane (PDMS). The uniformly attached adherent cells act as a convex lens, focusing the collimated light propagated through them. The intensity of the focused light indicates the density of the adherent cells. For Hela cells, a detection limit of 8.3 × 104 cells/mL with a detection range from 0.1 × 106 cells/mL to 1.0 × 106 cells/mL is achieved. This sensor is particularly useful for drug screening, cell pathology analysis, and cancer pre-diagnosis