المؤلفون: Jianqiu Zhao, Na Li, Xinyu Zhou, Zihan Yu, Mei Lan, Siyu Chen, Jiajia Miao, Yulai Li, Guiying Li, Fang Yang

المصدر: Micromachines, Vol 14, Iss 1, p 144 (2023)

مصطلحات موضوعية: cell lysis, E. coli, microfluidic, AC electric field, electroporation, Mechanical engineering and machinery, TJ1-1570

الوصف: Cell lysis is a key step for studying the structure and function of proteins in cells and an important intermediate step in drug screening, cancer diagnosis, and genome analysis. The current cell lysis methods still suffer from limitations, such as the need for large instruments, a long and time-consuming process, a large sample volume, chemical reagent contamination, and their unsuitability for the small amount of bacteria lysis required for point-of-care testing (POCT) devices. Therefore, a fast, chemical-free, portable, and non-invasive device needs to be developed. In the present study, we designed an integrated microfluidic chip to achieve E. coli lysis by applying an alternating current (AC) electric field and investigated the effects of voltage, frequency, and flow rate on the lysis. The results showed that the lysis efficiency of the bacteria was increased with a higher voltage, lower frequency, and lower flow rate. When the voltage was at 10 Vp-p, the lysis efficiency was close to 100%. The study provided a simple, rapid, reagent-free, and high-efficiency cleavage method for biology and biomedical applications involving bacteria lysis.

وصف الملف: electronic resource

Relation: https://www.mdpi.com/2072-666X/14/1/144; https://doaj.org/toc/2072-666X

URL الوصول: https://doaj.org/article/8c708e4bda7a47fd9a7e03152e0a3bf7

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المؤلفون: Mei Liu, Yuanli Cai, Lihao Zhang, Yiqun Wang

المصدر: Micromachines, Vol 12, Iss 11, p 1373 (2021)

مصطلحات موضوعية: portable mobile robot, quaternion implementation, complementary filter, extended Kalman filtering, attitude estimation, Mechanical engineering and machinery, TJ1-1570

الوصف: In robot inertial navigation systems, to deal with the problems of drift and noise in the gyroscope and accelerometer and the high computational cost when using extended Kalman filter (EKF) and particle filter (PF), a complementary filtering algorithm is utilized. By combining the Inertial Measurement Unit (IMU) multi-sensor signals, the attitude data are corrected, and the high-precision attitude angles are obtained. In this paper, the quaternion algorithm is used to describe the attitude motion, and the process of attitude estimation is analyzed in detail. Moreover, the models of the sensor and system are given. Ultimately, the attitude angles are estimated by using the quaternion extended Kalman filter, linear complementary filter, and Mahony complementary filter, respectively. The experimental results show that the Mahony complementary filtering algorithm has less computational cost than the extended Kalman filtering algorithm, while the attitude estimation accuracy of these two algorithms is similar, which reveals that Mahony complementary filtering is more suitable for low-cost embedded systems.

وصف الملف: electronic resource

Relation: https://www.mdpi.com/2072-666X/12/11/1373; https://doaj.org/toc/2072-666X

URL الوصول: https://doaj.org/article/b64dbb5552d04fc7afab2a8c576beaf9

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المؤلفون: Mei Liu, Weilin Su, Xiangzheng Qin, Kai Cheng, Wei Ding, Li Ma, Ze Cui, Jinbo Chen, Jinjun Rao, Hangkong Ouyang, Tao Sun

المصدر: Micromachines, Vol 12, Iss 3, p 248 (2021)

مصطلحات موضوعية: nanomanipulator, atomic force microscope, ZnO, mechanical/electrical characterization, piezoelectric property, Mechanical engineering and machinery, TJ1-1570

الوصف: ZnO nanomaterials have been widely used in micro/nano devices and structure due to special mechanical/electrical properties, and its characterization is still deficient and challenging. In this paper, ZnO nanomaterials, including nanorod and nanowire are characterized by atomic force microscope (AFM) and nanomanipulator embedded in scanning electron microscope (SEM) respectively, which can manipulate and observe simultaneously, and is efficient and cost effective. Surface morphology and mechanical properties were observed by AFM. Results showed that the average Young’s modulus of ZnO nanorods is 1.40 MPa and the average spring rate is 0.08 N/m. Electrical properties were characterized with nanomanipulator, which showed that the ZnO nanomaterial have cut-off characteristics and good schottky contact with the tungsten probes. A two-probe strategy was proposed for piezoelectric property measurement, which is easy to operate and adaptable to multiple nanomaterials. Experiments showed maximum voltage of a single ZnO nanowire is around 0.74 mV. Experiment criteria for ZnO manipulation and characterization were also studied, such as acceleration voltage, operation duration, sample preparation. Our work provides useful references for nanomaterial characterization and also theoretical basis for nanomaterials application.

وصف الملف: electronic resource

Relation: https://www.mdpi.com/2072-666X/12/3/248; https://doaj.org/toc/2072-666X

URL الوصول: https://doaj.org/article/da332b22a30d4173a9e36cc41bcd843b

المؤلفون: Mei Liu, Kai Cheng, Xiangzheng Qin, Zhenzhong Wei, Brandon Borom, Weilin Su, Jinbo Chen, Yunpeng Feng, Tao Wang, Jinjun Rao

المصدر: Micromachines, Vol 10, Iss 10, p 670 (2019)

مصطلحات موضوعية: scanning electron microscope (sem), interactive micromanipulation, nonconductive microparticle, virtual nano-hand strategy, Mechanical engineering and machinery, TJ1-1570

الوصف: Micro/nano-manipulation is the fabrication of particular constructs on devices at the micro/nano-scale. Precise manipulation of microparticles is one of the key technological difficulties in manufacturing micro/nano-scale components. Based on scanning electron microscopy and nanomanipulator, this paper adopts a direct push method to operate randomly distributed microparticles into ordered structures. A two-probe interaction strategy is proposed to enable microparticle movements in all directions efficiently and avoid scratching the substrate surface. To overcome the uncertainties in micromanipulation, a virtual nano-hand strategy was also implemented: long-range advance of each microparticle is realized by multiple single-step pushes, whose trajectory is theoretically analyzed. The pushes are well programmed to imitate effects of a more powerful and determined hand. Experimental results show that the theoretical single-step motion trajectory is in line with actual operation, and the proposed strategy can ensure precise operation of the microparticles in all directions and improve reliability and effectiveness of operation.

وصف الملف: electronic resource

Relation: https://www.mdpi.com/2072-666X/10/10/670; https://doaj.org/toc/2072-666X

URL الوصول: https://doaj.org/article/bebce313998a44b199ed39f6e630cd08

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المؤلفون: Ning Cao, Shaorong Xie, Zhizheng Wu, Mei Liu, Hengyu Li, Huayan Pu, Jun Luo, Zhenbang Gong

المصدر: Micromachines, Vol 8, Iss 8, p 257 (2017)

مصطلحات موضوعية: interactive micromanipulation, contact detection, picking and placement, nonconductive microsphere, Mechanical engineering and machinery, TJ1-1570

الوصف: In this paper, classified theoretical models, consisting of contact with and placement of microsphere and picking operations, are simplified and established to depict the interactive behaviors of external and internal forces in pushing manipulations, respectively. Sliding and/or rolling cases, resulting in the acceleration of micromanipulations, are discussed in detail. Effective contact detection is achieved by combining alterations of light-shadow and relative movement displacement between the tip-sphere. Picking operations are investigated by typical interactive positions and different end tilt angles. Placements are realized by adjusting the proper end tilt angles. These were separately conducted to explore the interactive operations of nonconductive glass microspheres in a scanning electron microscope. The experimental results demonstrate that the proposed contact detection method can efficiently protect the end-tip from damage, regardless of operator skills in initial positioning operations. E-beam irradiation onto different interactive positions with end tilt angles can be utilized to pick up microspheres without bending the end-tip. In addition, the results of releasing deviations away from the pre-setting point were utilized to verify the effectiveness of the placement tilt angles.

وصف الملف: electronic resource

Relation: https://www.mdpi.com/2072-666X/8/8/257; https://doaj.org/toc/2072-666X

URL الوصول: https://doaj.org/article/f8506c76572747d886c2bf5aad2b5752

المؤلفون: Zhizheng Wu, Xianghui Kong, Zhu Zhang, Junqiu Wu, Tao Wang, Mei Liu

المصدر: Micromachines, Vol 8, Iss 3, p 72 (2017)

مصطلحات موضوعية: magnetic fluid, deformable mirror, electromagnetic coil, two-layer, adaptive optics, Mechanical engineering and machinery, TJ1-1570

الوصف: In this paper, a new type of magnetic fluid deformable mirror (MFDM) with a two-layer layout of actuators is proposed to improve the correction performance for full-order aberrations with a high spatial resolution. The shape of the magnetic fluid surface is controlled by the combined magnetic field generated by the Maxwell coil and the two-layer array of miniature coils. The upper-layer actuators which have a small size and high density are used to compensate for small-amplitude high-order aberrations and the lower-layer actuators which have a big size and low density are used to correct large-amplitude low-order aberrations. The analytical model of this deformable mirror is established and the aberration correction performance is verified by the experimental results. As a new kind of wavefront corrector, the MFDM has major advantages such as large stroke, low cost, and easy scalability and fabrication.

وصف الملف: electronic resource

Relation: http://www.mdpi.com/2072-666X/8/3/72; https://doaj.org/toc/2072-666X

URL الوصول: https://doaj.org/article/3f3491cac5594703ac98393d3bdb8a82