Article
Chemistry, Analytical
Lin Zhang, Kaicong Cao, Longqi Ran, Huijun Yu, Wu Zhou
Summary: Anodic bonding plays an important role in the fabrication and packaging of MEMS devices, and the characteristics of the bonded interface significantly affect device stability and reliability. In this study, a contact model for a gold-silicon rough surface was established and the change in contact resistance was analyzed through finite element simulation and experimental measurement.
Article
Chemistry, Analytical
Ping Guo, Hongling Meng, Lin Dan, Jianye Zhao
Summary: A new method for wafer-level filling of MEMS vapor cells based on chemical reaction and evaporation is proposed in this article. Experimental results demonstrate that the presented method fulfills the requirements of sensors.
Article
Chemistry, Analytical
Zhujie Zhao, Cheng Lei, Ting Liang, Junna Zhang, Yuqiao Liu, Abdul Ghaffar, Jijun Xiong
Summary: A FAIMS-VOC gas sensor was designed and prepared to address the issues of large equipment size, long time, and high price in environmental VOC gas detection. The sensor, fabricated through the MEMS process, is small in size, fast in detection, low in power consumption, and capable of continuous operation. The sensor exhibited good repeatability and stability in detecting isobutylene and acetone gases, with linearities of 0.961 and 0.987, respectively. The response and recovery times for 50 ppm of isobutylene gas were 8 s and 6 s, while for acetone gas they were 9 s and 10 s.
Article
Chemistry, Physical
Shixing Zhu, Hui Jin, Zhisong Ou, Mengmeng Song, Jia Chen, Liejin Guo
Summary: In this paper, a high temperature and pressure visualization platform was used to study the hydrogen bonding degree of water in supercritical conditions. The results showed that hydrogen bonds still exist in supercritical water even at temperatures as high as 1013 K, mainly in the form of dimers and trimers. This finding is of significant importance for understanding the gasification mechanism of coal and organic matter in supercritical water.
JOURNAL OF MOLECULAR LIQUIDS
(2022)
Article
Biochemistry & Molecular Biology
Yannick Guinet, Laurent Paccou, Alain Hedoux
Summary: Designing co-crystals is a commonly used strategy to enhance the bioavailability of low molecular weight drugs. This study identified three pseudo polymorphic forms of the theophylline-citric acid co-crystal, each obtained through different synthesis methods, exhibiting varying degrees of stability due to the intermolecular forces involved. By employing low- and high-frequency Raman investigations, anhydrous and hydrated forms of the co-crystal were identified, depending on the preparation method. The study also revealed the role of different hydrogen bonding in the co-crystalline cohesion, depending on the presence of water.
Article
Chemistry, Analytical
Zhong Zhao, Guanying Huo, Huifang Li
Summary: Electroplating nanocrystallite Ni coating is widely used to improve the mechanical properties of metal structure surface, but the coating easily falls off due to internal compressive stress caused by the oxidation layer. In this study, the ultrasonic assisted electrochemical potential activation method was applied to solve the bonding problem. Through various experiments and testing methods, it was found that the ultrasonic activation method can effectively reduce the compressive stress and improve the bonding strength of the electroplated Ni coating. This research contributes to enhancing the interfacial bonding strength of metal MEMS devices.
Article
Thermodynamics
Chao Du, Cuirong Liu, Xu Yin, Haocheng Zhao
Summary: A new polyethylene glycol (PEG)-based solid polymer electrolyte with rare earth oxide CeO2 was synthesized using mechanical metallurgy for encapsulation bonding material in MEMS. The addition of CeO2 improved material crystallinity, ion migration, conductivity, peak current in bonding, and tensile strength, with optimal bonding efficiency achieved at 8 wt% CeO2. This study expands the applications of solid polymer electrolytes as encapsulation bonding materials.
ADVANCES IN MECHANICAL ENGINEERING
(2021)
Article
Chemistry, Analytical
Fanglan Yao, Pengcheng Xu, Hao Jia, Xinyu Li, Haitao Yu, Xinxin Li
Summary: The MEMS TGA technology utilizes temperature programming and microcantilever to achieve ultra-sensitive mass-loss analysis and high-efficiency rapid heating, meeting the higher requirements of TGA.
ANALYTICAL CHEMISTRY
(2022)
Article
Chemistry, Analytical
Yeran Bai, Zhongyue Guo, Fatima C. Pereira, Michael Wagner, Ji-Xin Cheng
Summary: A mid-infrared photothermal-fluorescence in situ hybridization (MIP-FISH) platform is developed for simultaneous identification and metabolic analysis of microbes with single-cell resolution and high throughput. By improving MIP imaging, isotopically labeled compounds incorporated into proteins of individual bacterial cells can be sensitively detected, while FISH labeling with rRNA-targeted probes enables the identification of the analyzed cells. In proof-of-concept experiments, MIP-FISH successfully discriminates and identifies labeled bacterial cells within a complex human gut microbiome sample based on the clear spectral red shift in the protein amide I region caused by incorporation of 13C atoms from 13C-labeled glucose. This study opens up new opportunities for single-cell structure-function analyses in microbiology.
ANALYTICAL CHEMISTRY
(2023)
Article
Polymer Science
Weixuan Zhang, Mixue Wang, Haocheng Zhao, Xin Liu, Ruoyun Liu, Xiaoling Xie, Yuling Wu
Summary: PEO-HBPUEs as polymer electrolyte substrate materials show promising applications in MEMS devices, with low glass transition temperatures, good thermal stabilities, and suitable mechanical properties. The PEO-based electrolyte component contributes to increased ionic conductivity in the materials.
JOURNAL OF APPLIED POLYMER SCIENCE
(2021)
Article
Physics, Applied
Tara Pena, Aditya Dey, Shoieb A. Chowdhury, Ahmad Azizimanesh, Wenhui Hou, Arfan Sewaket, Carla Watson, Hesam Askari, Stephen M. Wu
Summary: We demonstrate controllable manipulation of a moire superlattice interference pattern in twisted bilayer graphene through the use of designable device-level heterostrain. By depositing stressed thin films onto the graphene samples, we can control the magnitude and directionality of heterostrain. Raman spectroscopy and simulations confirm the breaking of C-3 rotational symmetry and tunable periodicity in the moire superlattices under uniaxial or biaxial strain.
APPLIED PHYSICS LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Chao Xu, Junbo Wang, Deyong Chen, Jian Chen, Bowen Liu, Wenjie Qi, Tian Liang, Xu She
Summary: A method was developed to fabricate MEMS-based integrated electrodes for electrochemical seismic sensors, which employed a three-layer anodic bonding structure of silicon-glass-silicon. The proposed integrated electrodes demonstrated high sensitivity and integration, with a cross-correlation coefficient of 0.998 and sensitivity of 5956 V/(m/s) @1Hz. This electrode represents a sensitive structure with both high sensitivity and high integration in electrochemical seismic sensors.
IEEE SENSORS JOURNAL
(2021)
Article
Chemistry, Physical
Ying Chang, Donghui Fu, Mingyuan Sun, Saisai He, Wei Qiu
Summary: Micro Raman spectroscopy is an effective method for quantitative analysis of internal stress in semiconductor materials and structures. However, decoupling the stress components for {100} monocrystalline silicon (c-Si) remains challenging. In this study, physical and simulation experiments were used to investigate the influence of objective lens numerical aperture (NA) on Raman stress characterization. The results showed that using lenses with different NAs accurately obtained the principal stress sum but could not decouple the in-plane stress components. Further simulation experiments demonstrated that the differences in Raman shifts caused by different stress states were smaller than the resolution of the existing Raman microscope system, making it difficult to identify in the experimental results.
Article
Chemistry, Inorganic & Nuclear
Neenu Saini, Ruby Jindal, Archana Tripathi
Summary: The Raman and infrared (IR) phonons of bilayered tetragonal Srn+1BnO3n+1 (B = V, Cr, Fe, Co) compounds were analyzed using Wilson's GF-Matrix Method. The optical wavenumbers were theoretically assigned for Sr3V2O7, Sr3Cr2O7, and Sr3Co2O7 compounds. The Raman modes of Sr3Fe2O7 calculated in literature did not match well with the experimental frequencies. Improved results for the Raman vibrational modes were calculated and reported using data from the isostructural compounds Sr3Ti2O7 and Sr3Mn2O7. The impact of cation-B exchange on lattice dynamics and the effect of B-cations on apical bonds were also analyzed.
SOLID STATE SCIENCES
(2023)
Review
Chemistry, Analytical
Wenqiang Pei, Rui Hu, Hao Liu, Le Wang, Yongchao Lai
Summary: An analytical method with high sensitivity and selectivity is needed to understand the impact of nanoplastics. This review article discusses the challenges in nanoplastic analysis using Raman spectroscopy and provides an overview of recent progress in this field. Various techniques, such as hyphenated technology and surface enhanced Raman spectroscopy, are highlighted for their efforts to improve the sensitivity, accuracy, and feasibility of Raman spectroscopy for nanoplastic analysis. The article concludes with a summary of current challenges and future research opportunities in advanced Raman spectroscopy for nanoplastic analysis.
TRAC-TRENDS IN ANALYTICAL CHEMISTRY
(2023)
