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Design of micropipette System with High Precision for Small Enzyme Immunoassay Analyzer

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Journal of Shanghai Jiaotong university(Science) 2019年第5期24卷 605-615页

作者： SHANG Zhiwu ZHOU Xiangping LI Cheng ZHOU Xinyu School of Mechanical Engineering Tianjin Polytechnic University of China

A small auto micropipette system is developed to improve the reliability and accuracy of the automatic enzyme immunoassay analyzer’s microscale pipetting system. A sophisticated injection mechanism is designed by the means of dislocation parallel distribution of the screw and injector piston rod. It possesses the function of pipetting, taking and removing the pipette tips. In the control system, STM32 controller is used, controlling the single-axis S-type acceleration/deceleration algorithm and multi-threaded coordinated motion. The acceleration/deceleration curves are analyzed and optimized by using the method of segmentation;a minimum injection rate of 1 μL and a step rate of 0.05 μL are realized. The method of digital image processing is used to detect the amount of pipetting in micro-pipetting quantitatively. The liquid area is extracted by background contrast method, and the liquid volume in the tip is obtained by combining the geometric characteristics of the disposable tip, when the pipetting capacity is not qualified to carry out specific guidance on the pipetting system, and avoid the blocking needle, bubble and other abnormal pipetting phenomenon on the impact of pipetting accuracy. The experimental results show that the combination of the automatic sampling system and the image flow detection system can effectively improve the precision and reliability of the micro-pipetting system. Finally, the injection accuracy of the system at the test points with 10, 50 and 100 μL liquid volumes reaches 1.8%, 1.28% and 1.15%respectively.

关键词： enzyme immunoassay analyzer micropipette image processing motion control error compensation

Facilitated Ion Transfer Across the Micro-liquid/Liquid Interface Supported at the Tip of a Silanized micropipette

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Chemical Research in Chinese Universities 2003年第1期19卷 59-62页

作者： SU Bin SHAO Yuan-Hua StateKeyLaboratoryofElectroanalyticalChemistry ChangchunInstituteofAppliedChemistryChineseAcademyofSciencesChangchun130022P.R.China StateKeyLaboratoryofElectroanalyticalChemistry

Glass micropipettes with silanized inner walls can be filled with an organic solvent for voltammetric measurements in an aqueous solution. This arrangement was employed to investigate systematically the mechanism of facilitated potassium ion transfer by an ionophore dibenzo 18 crown 6(DB18C6) across a micro water/1,2 dichloroethane(W/DCE) interface supported at the tip of a silanized micropipette. Our experimental results verify that this facilitated ion transfer across the liquid/liquid interface did occur by an interfacial complexation dissociation process(TIC TID mechanism). The ratio of the diffusion coefficient of DB18C6 to that of its complexed ion in the DCE phase was calculated to be 1.74±0.07.

关键词： Silanization micropipette Facilitated K + transfer Mechanism

Mechanical Properties of Cells Estimated by Different Models of micropipette Aspiration

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医用生物力学 2019年第A1期34卷 1-2页

作者： Weiyi Chen College of Biomedical Engineering Taiyuan University of Technology

Background The mechanical properties are related with many biological functions of cells. Accurate quantification of the mechanical properties of living cells require the combined use of experimental techniques and theoretical models. micropipette aspiration (MPA) is one of common techniques in determining mechanical properties of the living cells. The halfspace model (HSM) is employed in MPA technique. However,in the conditions of linear constitutive relations and small deformations,the HSM is inadequate for characterizing the MPA of a spherical cell in two respects. Firstly,the cell size is fairly finite other than semi-infinite to the inner radius of a micropipette;Secondly,cells are compressible,with a Poisson’s ratioνvarying from 0. 2 to 0. 4 (23-25) instead of incompressible (ν=0. 5). Thus,a more accurate model is *** this study,the viscoelastic expressions were derived from our previous MPA test. Then,a sphere model (SM) employed to analyze mechanical properties of rabbit chondrocytes combined with the experimental data. Differences in mechanical properties estimated by different mechanical models were *** A sphere model (SM) was employed. The relative dimension of cell to micropipette and the compressibility of the cell were taken into account,as shown in Fig. 1a.■Fig.1 Sphere model of the MPA of a single cell employing different constitutive relationships The approximate expression for the aspirated length was obtained from our previous study as follows:■Furthermore,assuming that the cell behaves as a homogeneous and isotropic standard linear solid (Fig. 1b),two viscoelastic creep expressions of the aspirated length for incompressible sphere model (ICSM) and for compressible sphere model (CSM) were derived by elastic-viscoelastic correspondence principle and integral transformation as Eqs.(2) and (3)respectively.■Results(1) Comparisons of models The elastic modulus from the ICSM was 47. 4%higher than that of the half-space model (HSM)

关键词： micropipette aspiration mechanical models mechanical properties compressibility of cell cell dimension

Ion current rectification: from nanoscale to microscale

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Science China Chemistry 2019年第10期62卷 1346-1359页

作者： Tianyi Xiong Kailin Zhang Yanan Jiang Ping Yu Lanqun Mao Beijing National Laboratory for Molecular Sciences Key Laboratory of Analytical Chemistry for Living BiosystemsInstitute of ChemistryChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100149China

Ion current rectification(ICR)is an electrodynamic phenomenon in electrolyte solution which is defined as the asymmetric potential-dependent ion flux through a confined environment,giving rise to asymmetric electrical current-voltage characteristics induced by the influence of an asymmetric electrical double layer *** the discovery of the ICR phenomenon,the observation and application of ICR at nanoscale and microscale have been widely investigated experimentally and ***,the recent progress of ICR from nanoscale to microscale is systematically ***/micropore structures of different materials,shapes and pore sizes are first ***,the factors influencing ICRs by thermodynamically or kinetically regulating the electrical double layer structure are ***,theoretical models are presented to explain the mechanism of *** on the understanding of this phenomenon,the applications,especially in biosensors,are ***,future developments of this area are briefly *** review covers the representative related literature published since 2010 and is intended to give a systematic introduction to this area.

关键词： ion current rectification ion transport nanopore nanochannel micropipette