JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY

Nanoscale Metal-Organic Frameworks: Stimulus-Response and Applications

Chen Zhao, Rui Jing, Shanshan Wang, Xiaoying Tang

2022, 31(3): 225-237. doi:10.15918/j.jbit1004-0579.2022.007

[Abstract](398) [FullText HTML](195) [PDF 3949KB](44)

Abstract:
Metal-organic frameworks (MOFs), a crystalline porous material with a periodic network structure formed by the self-assembly of transition metal ions and organic ligands, have been widely applied in various fields due to their rich composition and structural diversity. Among various types of MOFs, stimuli-responsive MOFs have gained increasing attention in recent years, because of their broad application in the field of physics, biology, and chemistry. In this review, we analyzed and classified the mechanism of stimulus-response MOFs (pH response, glucose response, GSH response, light response, temperature response) and their applications in drug delivery, adsorption and luminescence functions, magnetization and catalysis functions, probe and sensor.

Application of Micro Electro Mechanical System (MEMS) Technology in Photoacoustic Imaging

Lixia Bao, Xiaoying Tang, Zhenqi Jiang

2022, 31(3): 238-250. doi:10.15918/j.jbit1004-0579.2022.015

[Abstract](202) [FullText HTML](181) [PDF 4164KB](26)

Abstract:
Photoacoustic imaging (PAI) is a new biomedical imaging technology that provides a mixed contrast mechanism and excellent spatial resolution in biological tissues. It is a non-invasive technology that can provide in vivo anatomical and functional information. This technology has great application potential in microscopic imaging and endoscope system. In recent years, the development of micro electro mechanical system (MEMS) technology has promoted the improvement and miniaturization of the photoacoustic imaging system, as well as its preclinical and clinical applications. This paper introduces the research progress of MEMS technology in photoacoustic microscope systems and the miniaturization of photoacoustic endoscope ultrasonic transducers, and points out the shortcomings of existing technology and the direction of future development.

A New Class of Biodegradable Organic Optoelectronic Materials: α-Oligofurans

Siyu Ji, Xuhui Jin

2022, 31(3): 251-258. doi:10.15918/j.jbit1004-0579.2022.014

[Abstract](206) [FullText HTML](83) [PDF 1155KB](24)

Abstract:
Organic optoelectronic materials have received considerable attention due to their great potentials in electronic devices, such as organic field-effect transistors (OFETs), organic light-emitting diodes (OLED) and organic photovoltaic cells (OPV). Besides, their fascinating properties of flexibility, biocompatibility, molecular diversity, low-cost and solution processability bring new opportunities in bioelectronics in the past decade. While almost all known organic optoelectronic materials are obtained from unrenewable fossil resources and nondegradable, a new family of organic optoelectronic materials is now emerging, which can be obtained from green plants and are biodegradable. Meanwhile, they exhibit excellent optoelectronic properties. This review summarized the synthesis and important molecular properties of this new class of biodegradable organic optoelectronic materials: α-oligofurans. Recent progress of furan-based materials and the existing challenges are also discussed to stimulate further advances in the study of this class of materials.

Design of Implant Prosthesis for Bone Injury Repair Considering Stress Shielding Effect

Yixin Shao, Ye Zhu, Tianmin Guan, Qi Hu, Baozhong Wei, Bing Lin, Liyan Zhang, Qian Cao

2022, 31(3): 259-274. doi:10.15918/j.jbit1004-0579.2022.053

[Abstract](113) [FullText HTML](48) [PDF 2955KB](19)

Abstract:
The failure of bone injury repair surgery is mostly due to the stress shielding effect caused by the difference of elastic modulus between the implant prosthesis and human bone, resulting in a great damage to patients. To solve this problem, in this study, the influencing factors of the elastic modulus of implant prosthesis were investigated, the relationship between the elastic modulus of the implanted prosthesis and the influencing factors was analyzed, and then a design method of the implant prosthesis to reduce the stress shielding effect by adjusting the unit module to control the elastic modulus was established. This method was used for the biomechanical simulation to simulate the displacement and stress distribution between the implant prosthesis and the surrounding bone tissue, and then the reliability of the method was verified. The implant prosthesis with an elastic modulus consistent with that of the experimental dog bone was made by this method, and used for the animal experiments. The effects of implant prosthesis with different modulus on the growth of surrounding bone tissue were observed, and at the same time, the reliability of the implant design method and the results of biomechanical simulation were verified. It is confirmed that this method can effectively reduce the stress concentration of implant prosthesis by more than 15.4% and increase the growth of bone tissue by more than 21%.

A Microfluidic System with Active Mixing for Improved Real-Time Isothermal Amplification

Dianlong Yang, Xiaodan Jiang, Yijie Zhou, Xiaobin Dong, Luyao Liu, Lulu Zhang, Xianbo Qiu

2022, 31(3): 275-284. doi:10.15918/j.jbit1004-0579.2022.026

[Abstract](73) [FullText HTML](28) [PDF 1548KB](12)

Abstract:
To improve the performance of real-time recombinase polymerase amplification (RPA), a microfluidic system with active mixing is developed to optimize the reaction dynamics. Instead of adopting a single typical reaction chamber, a specific reactor including a relatively large chamber in center with two adjacent zig-zag channels at two sides is integrated into the microfluidic chip. Active mixing is achieved by driving the viscous reagent between the chamber and the channel back and forth periodically with an outside compact peristaltic pump. To avoid reagent evaporation, one end of the reactor is sealed with paraffin oil. A hand-held companion device is developed to facilitate real-time RPA amplification within 20 min. The whole area of the reactor is heated with a resistance heater to provide uniform reaction temperature. To achieve real-time monitoring, a compact fluorescence detection module is integrated into the hand-held device. A smartphone with custom application software is adopted to control the hand-held device and display the real-time fluorescence curves. The performances of two cases with and without active on-chip mixing are compared between each other by detecting African swine fever viruses. It has been demonstrated that, with active on-chip mixing, the amplification efficiency and detection sensitivity can be significantly improved.

A Feature Extraction Method for scRNA-seq Processing and Its Application on COVID-19 Data Analysis

Xiumin Shi, Xiyuan Wu, Hengyu Qin

2022, 31(3): 285-292. doi:10.15918/j.jbit1004-0579.2022.052

[Abstract](1181) [FullText HTML](554) [PDF 1286KB](28)

Abstract:
Single-cell RNA-sequencing (scRNA-seq) is a rapidly increasing research area in biomedical signal processing. However, the high complexity of single-cell data makes efficient and accurate analysis difficult. To improve the performance of single-cell RNA data processing, two single-cell features calculation method and corresponding dual-input neural network structures are proposed. In this feature extraction and fusion scheme, the features at the cluster level are extracted by hierarchical clustering and differential gene analysis, and the features at the cell level are extracted by the calculation of gene frequency and cross cell frequency. Our experiments on COVID-19 data demonstrate that the combined use of these two feature achieves great results and high robustness for classification tasks.

Mixing Dynamics and Synthesis Performance of Staggered Herringbone Micromixer for Limit Size Lipid Nanoparticles

Shuai Zhang, Yunlong Fan, Chenmu Xue, Yuanzhan Yang, Xiaoqiong Li, Xiaodong Chen, Yulin Deng

2022, 31(3): 293-301. doi:10.15918/j.jbit1004-0579.2022.035

[Abstract](223) [FullText HTML](98) [PDF 8897KB](27)

Abstract:
Staggered herringbone micromixer has shown good efficiency of mixing and performance of synthesizing nanoparticles. To bring a detailed understanding of the mixing dynamics and synthesis performance of this kind of micromixer, this paper carries out a high-fidelity numerical simulation and a parametrial experimental study on a well-established design. A passive tracer is induced in the numerical simulation to analyze mixing dynamics induced by the staggered herringbone structures. Three effects are identified to reveal the underlying mechanisms, including folding, stretching, and splitting. To the authors’ knowledge, the splitting effect is identified for the first time by the isosurface of the passive tracer, to show the high efficiency of the staggered herringbone design. The micromixer is then used to synthesize lipid nanoparticles by mixing a mixture of lipid and poly (lactic-co-glycolic acid) (PLGA) solutions with deionized water. Under a wide mass ratio of lipid and PLGA solutions, nanoparticles with good monodispersity are synthesized to reflect the good compatibility of the micromixer and the mixture. In addition, an optimized mass ratio is identified from the parametrical experiment.

Effect of Auxiliary Gas Flow Parameters on Microstructure and Properties of Ta Coatings Prepared by Three-Cathode Atmosphere Plasma Spraying

Jing Cui, Haiyang Xia, Lang Cui, Guang Liu

2022, 31(3): 302-316. doi:10.15918/j.jbit1004-0579.2022.009

[Abstract](185) [FullText HTML](70) [PDF 4566KB](17)

Abstract:
Based on the three-cathode plasma spraying system, tantalum (Ta) coatings were prepared on the substrate of CuCrZr alloy. The effects of different auxiliary gas (helium) flow rates on the microstructure, phase composition, mechanical and wear resistance properties of Ta coatings were studied. The results showed that the oxidation degree of the coatings decreases first and then increases with the increase of the auxiliary gas flow. When the auxiliary gas flow rate is 70 L·min^–1, the oxidation degree of the coating is the lowest, minimum value of the porosity is 0.21%, and the bonding strength reaches the maximum, 59.3 MPa. At this time, the coating wear rate is 0.0012 mm³·N^–1·m^–1with the best wear resistance. This indicates that the auxiliary gas flow has an important influence on the quality and surface mechanical properties of tantalum coating.

Chip Layout for Adaptive Line Enhancer Design using Adaptive Filtering Algorithms and Metrics Computation for Auscultation Signal Separation

S. Rajkumar, K. Sathesh, Bayisa Taye Mulatu

2022, 31(3): 317-326. doi:10.15918/j.jbit1004-0579.2021.102

[Abstract](183) [FullText HTML](66) [PDF 6205KB](24)

Abstract:
Currently, the growth of micro and nano (very large scale integration-ultra large-scale integration) electronics technology has greatly impacted biomedical signal processing devices. These high-speed micro and nano technology devices are very reliable despite their capacity to operate at tremendous speed, and can be designed to consume less power in minimum response time, which is particularly useful in biomedical products. The rapid technological scaling of the metal-oxide-semiconductor (MOS) devices aids in mapping multiple applications for a specific purpose on a single chip which motivates us to design a sophisticated, small and reliable application specific integrated circuit (ASIC) chip for future real time medical signal separation and processing (digital stethoscopes and digital microelectromechanical systems (MEMS) microphone). In this paper, ASIC level implementation of the adaptive line enhancer design using adaptive filtering algorithms (least mean square (LMS) and normalized least mean square (NLMS)) integrated design is used to separate the real-time auscultation sound signals effectively. Adaptive line enhancer (ALE) design is implemented in Verilog hardware description language (HDL) language to obtain both the network and adaptive algorithm in cadence Taiwan Semiconductor Manufacturing Company (TSMC) 90 nm standard cell library environment for ASIC level implementation. Native compiled simulator (NC) sim and RC lab were used for functional verification and design constraints and the physical design is implemented in Encounter to obtain the Geometric Data Stream (GDS II). In this architecture, the area occupied is 0.08 mm, the total power consumed is 5.05 mW and the computation time of the proposed system is 0.82 µs for LMS design and the area occupied is 0.14 mm, the total power consumed is 4.54 mW and the computation time of the proposed system is 0.03 µs for NLMS design that will pave a better way in future electronic stethoscope design.

2022 Vol. 31, No. 3