10 research outputs found

    Automated single cell isolation from suspension with computer vision

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    Current robots can manipulate only surface-attached cells seriously limiting the fields of their application for single cell handling. We developed a computer vision-based robot applying a motorized microscope and micropipette to recognize and gently isolate intact individual cells for subsequent analysis, e.g., DNA/RNA sequencing in 1–2 nanoliters from a thin (~100 μm) layer of cell suspension. It can retrieve rare cells, needs minimal sample preparation, and can be applied for virtually any tissue cell type. Combination of 1 μm positioning precision, adaptive cell targeting and below 1 nl liquid handling precision resulted in an unprecedented accuracy and efficiency in robotic single cell isolation. Single cells were injected either into the wells of a miniature plate with a sorting speed of 3 cells/min or into standard PCR tubes with 2 cells/min. We could isolate labeled cells also from dense cultures containing ~1,000 times more unlabeled cells by the successive application of the sorting process. We compared the efficiency of our method to that of single cell entrapment in microwells and subsequent sorting with the automated micropipette: the recovery rate of single cells was greatly improved

    Sistema de seguimiento automático por imágenes

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    En este trabajo se presenta el desarrollo de un sistema de seguimiento servo-controlado por imágenes. Se comienza partiendo de un algoritmo de seguimiento por procesamiento de imágenes de video desarrollado previamente, en el que la cámara de filmación se encuentra estática y se sigue a un objeto que se desplaza en el cuadro de la imagen enmarcándolo con una ventana. Se utiliza la posición de esa ventana de seguimiento para determinar las correcciones necesarias para mover a la cámara mediante servomotores de manera de mantener el objeto en el centro de la imagen. Para esto se generó una realimentación visual apropiada para un pedestal servo controlado de tipo azimutelevación cuyos ejes pueden moverse mediante dos motores de corriente continua. Se calibra la cámara de filmación, y se implementó una estrategia de control de realimentación de estado velocidad utilizando un algoritmo PID como estimador. Finalmente se presentan los resultados de los ensayos del sistema en tres escenarios diferentes con resultados exitosos en el seguimiento de i) un avión comercial, ii) un helicóptero en maniobra local y iii) un ave. Los resultados exitosos validan las etapas anteriores, y fundamentan mejoras futuras.Fil: García, Santiago. Instituto Universitario Aeronáutico. Córdoba; Argentina.Fil: Curetti, María. Instituto Universitario Aeronáutico. Córdoba; Argentina.Fil: Arri, Gabriela. Instituto Universitario Aeronáutico. Córdoba; Argentina.Fil: Pucheta, Julián. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Mathe, Ladislao. Instituto Universitario Aeronáutico. Córdoba; Argentina.Sistemas de Automatización y Contro

    Three Dimensional Auto-Alignment of the ICSI Pipette

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    Sistema de seguimiento automático por imágenes

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    En este trabajo se presenta el desarrollo de un sistema de seguimiento servo-controlado por imágenes. Se comienza partiendo de un algoritmo de seguimiento por procesamiento de imágenes de video desarrollado previamente, en el que la cámara de filmación se encuentra estática y se sigue a un objeto que se desplaza en el cuadro de la imagen enmarcándolo con una ventana. Se utiliza la posición de esa ventana de seguimiento para determinar las correcciones necesarias para mover a la cámara mediante servomotores de manera de mantener el objeto en el centro de la imagen. Para esto se generó una realimentación visual apropiada para un pedestal servo controlado de tipo azimutelevación cuyos ejes pueden moverse mediante dos motores de corriente continua. Se calibra la cámara de filmación, y se implementó una estrategia de control de realimentación de estado velocidad utilizando un algoritmo PID como estimador. Finalmente se presentan los resultados de los ensayos del sistema en tres escenarios diferentes con resultados exitosos en el seguimiento de i) un avión comercial, ii) un helicóptero en maniobra local y iii) un ave. Los resultados exitosos validan las etapas anteriores, y fundamentan mejoras futuras.Sociedad Argentina de Informática e Investigación Operativ

    Sistema de seguimiento automático por imágenes

    Get PDF
    En este trabajo se presenta el desarrollo de un sistema de seguimiento servo-controlado por imágenes. Se comienza partiendo de un algoritmo de seguimiento por procesamiento de imágenes de video desarrollado previamente, en el que la cámara de filmación se encuentra estática y se sigue a un objeto que se desplaza en el cuadro de la imagen enmarcándolo con una ventana. Se utiliza la posición de esa ventana de seguimiento para determinar las correcciones necesarias para mover a la cámara mediante servomotores de manera de mantener el objeto en el centro de la imagen. Para esto se generó una realimentación visual apropiada para un pedestal servo controlado de tipo azimutelevación cuyos ejes pueden moverse mediante dos motores de corriente continua. Se calibra la cámara de filmación, y se implementó una estrategia de control de realimentación de estado velocidad utilizando un algoritmo PID como estimador. Finalmente se presentan los resultados de los ensayos del sistema en tres escenarios diferentes con resultados exitosos en el seguimiento de i) un avión comercial, ii) un helicóptero en maniobra local y iii) un ave. Los resultados exitosos validan las etapas anteriores, y fundamentan mejoras futuras.Sociedad Argentina de Informática e Investigación Operativ

    Single-Cell Analysis Reveals Early Manifestation of Cancerous Phenotype in Pre-Malignant Esophageal Cells

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    abstract: Cellular heterogeneity plays a pivotal role in a variety of functional processes in vivo including carcinogenesis. However, our knowledge about cell-to-cell diversity and how differences in individual cells manifest in alterations at the population level remains very limited mainly due to the lack of appropriate tools enabling studies at the single-cell level. We present a study on changes in cellular heterogeneity in the context of pre-malignant progression in response to hypoxic stress. Utilizing pre-malignant progression of Barrett’s esophagus (BE) as a disease model system we studied molecular mechanisms underlying the progression from metaplastic to dysplastic (pre-cancerous) stage. We used newly developed methods enabling measurements of cell-to-cell differences in copy numbers of mitochondrial DNA, expression levels of a set of mitochondrial and nuclear genes involved in hypoxia response pathways, and mitochondrial membrane potential. In contrast to bulk cell studies reported earlier, our study shows significant differences between metaplastic and dysplastic BE cells in both average values and single-cell parameter distributions of mtDNA copy numbers, mitochondrial function, and mRNA expression levels of studied genes. Based on single-cell data analysis, we propose that mitochondria may be one of the key factors in pre-malignant progression in BE.The article is published at http://journals.plos.org/plosone/article?id=10.1371/journal.pone.007536

    Vision guided automation for intra-cytoplasmic sperm injection

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    Biological cell injection is an effective technique in which a foreign material is directly introduced into the target cell. Intracytoplasmic Sperm Injection (ICSI) is a microinjection technique which is used for infertility treatment. In this technique, a single sperm cell is directly injected into an oocyte using micropipettes. The operations in this application are manually controlled by an embryologist and more importantly, this reduces the accuracy, repeatability, and consistency of the operation. Therefore, the full automation is a prerequisite for microinjection operations, particularly in ICSI application. This thesis focuses on enhancing the microinjection procedure by developing vision-guided processes prior to and during the operation. Initially, a vision-controlled technique was proposed to align the injection and holding pipettes in three orthogonal axes which is essential for successful microinjection. To conduct reliable injection, the vibrational displacement of the injection pipette’s tip needs to be evaluated and improved before the operations continue further. A novel vision-based sensor was developed to measure the displacement changes at the tip in three orthogonal axes. By employing the developed vision sensor, the effect of injection speed on vibrational displacement creation was analysed to determine the value of various injection parameters, such as force fluctuation, and penetration force on cell damages. An ultimate automation task is required in microinjection to position the randomly located biological cell within the Petri dish to the system’s field of view. The proposed technique fills a gap in the literature by proposing a real-time cell recognising and positioning system that can be employed with different types of biological cells at various maturation stages, as well as with different microscope types that are being used in microinjection applications

    Cooperative Manipulation using a Magnetically Navigated Microrobot and a Micromanipulator

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    The cooperative manipulation of a common object using two or more manipulators is a popular research field in both industry and institutions. Different types of manipulators are used in cooperative manipulation for carrying heavy loads and delicate operations. Their applications range from macro to micro. In this thesis, we are interested in the development of a novel cooperative manipulator for manipulation tasks in a small workspace. The resultant cooperative manipulation system consists of a magnetically navigated microrobot (MNM) and a motorized micromanipulator (MM). The MNM is a small cylinder permanent magnet with 10mm diameter and 10mm height. The MM model is MP-285 which is a commercialized product. Here, the MNM is remotely controlled by an external magnetic field. The property of non-contact manipulation makes it a suitable choice for manipulation in a confined space. The cooperative manipulation system in this thesis used a master/slave mechanism as the central control strategy. The MM is the master side. The MNM is the slave side. During the manipulation process, the master manipulator MM is always position controlled, and it leads the object translation according to the kinematic constraints of the cooperative manipulation task. The MNM is position controlled at the beginning of the manipulation. In the translation stage, the MNM is switched to force control to maintain a successful holding of the object, and at the same time to prevent damaging the object by large holding force. Under the force control mode, the motion command to the MNM is calculated from a position-based impedance controller that enforces a relationship between the position of the MNM and the force. In this research, the accurate motion control of both manipulators are firstly studied before the cooperative manipulation is conducted. For the magnetic navigation system, the magnetic field in its workspace is modeled using an experimental measurement data-driven technique. The developed model is then used to develop a motion controller for navigating of a small cylindrical permanent magnet. The accuracy of motion control is reached at 20 µm in three degrees of freedom. For the motorized micromanipulator, a standard PID controller is designed to control its motion stage. The accuracy of the MM navigation is 0.8 µm. Since the MNM is remotely manipulated by an external magnetic field in a small space, it is challenging to install an on-board force sensor to measure the contact force between the MNM and the object. Therefore, a dual-axial o_-board force determination mechanism is proposed. The force is determined according to the linear relation between the minimum magnetic potential energy point and the real position of the MNM in the workspace. For convenience, the minimum magnetic potential energy point is defined as the Bmax in the literature. In this thesis, the dual-axial Bmax position is determined by measuring the magnetic ux density passing through the workspace using four Hall-effect sensors installed at the bottom of an iron pole-piece. The force model is experimentally validated in a horizontal plane with an accuracy of 2 µN in the x- and y- direction of horizontal planes. The proposed cooperative manipulator is then used to translate a hard-shell small object in two directions of a vertical plane, while one direction is constrained with a desired holding force. During the manipulation process, a digital camera is used to capture the real-time position of the MNM, the MM end-effector, and the manipulated object. To improve the performance of force control on the MNM, the proposed dual-axial force model is used to examine the compliant force control of the MNM while it is navigated to contact with uncertain environments. Here, uncertain refers to unknown environmental stiffness. An adaptive position-based impedance controller is implemented to estimate the stiffness of the environment and the contact force. The controller is examined by navigating the MNM to push a thin aluminum beam whose stiffness is unknown. The studied cooperative manipulation system has potential applications in biomedical microsurgery and microinjection. It should be clarified that the current system setup with 10mm ×10 mm MNM is not proper for this micromanipulation. In order to conduct research on microinjection, the size of the MNM and the end-effector of the MNM should be down-scaled to micrometers. In addition, the navigation accuracy of the MNM should also be improved to adopt the micromanipulation tasks
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