An IPMC Driven Valveless Pump for Biomedical Applications

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dc.contributor.advisor Aw, K en
dc.contributor.advisor Sharma, R en
dc.contributor.advisor McDaid, A en Wang, Jiaqi en 2017-06-07T21:32:51Z en 2016 en
dc.identifier.uri en
dc.description.abstract In recent decades, biomedical pumps, the 'heart' of a hydraulic clinical device, continue to attract an increasing amount of attention as the demand for 'high-quality' medical treatment grows. In general, every drug or hormone has its own desired range of concentration which is controlled by the human body. When required to be within a precise concentration range, such as the glycaemic range, conventional drug dispensing methods are unable to deliver the necessary dose in a near-natural manner without fluctuation, therefore a controllable pumping device is necessary. The main motivation for this research was to develop a prototype for biomedical pumps which features accuracy, compactness, and efficiency. Among the many factors in pump design, the actuator and the flow rectifying element are the two most important issues to be considered. A biocompatible and scalable IPMC (ionic polymer-metal composite) was chosen for the actuator and a gradually expanding/contracting diffuser/nozzle was selected as the static flow directing element, (where no mechanical valve exists), due to its advantages in the minimizing dimension. However, from the review of previous studies, it is found that there are clear discrepancies and missing information, not only in the diffuser/nozzle pair but also in IPMC control and the means for compact sensing. Therefore, this study aims to investigate these issues, bridge the gaps and finally develop a prototype for the IPMC driven diffuser/nozzle valveless pump. In the first part of this research, a numerical simulation of various diffuser/nozzle dimensions in terms of half angle, area ratio, was studied to find the most efficient structure which was then testified by a macro scale pump experiment with interchangeable diffuser/nozzle layers. The half angle was shown to have a significant effect on diffuser efficiency and the optimum half angle, where the highest flow rectifying capability was exhibited; this was found to decrease with Reynolds number. In addition to the investigation of the classical diffuser/nozzle element, an improved diffuser/nozzle structure with re-entrance at the nozzle end was also proposed for efficiency enhancement. The re-entrance structure brings about extra pressure loss in nozzle direction and thus increases the pressure loss difference between two directions and the flow directing capability of the whole pump. The dimensionless flow characteristics of diffuser/nozzle element, the conclusions and novel structure proposed here can be employed as a guideline for valveless pump design and further applied in a broader dimension range. Considering the desire for compactness of biomedical pumps, a practical integrated displacement sensor needs to be developed as a substitute for sensors that are currently popular, such as the laser and strain gauge, but which are either bulky or force constraint, to serve as the feedback in the closed loop controller. A PCB (print circuit board) coil sensor was selected due to its contactless and compact sensing mechanism and exhibited a performance that was comparative to that of the laser sensor in measuring the deflection of IPMC actuator driven by a chirp signal. Finally, the valveless pump prototype was built using 3D printing and a double chamber parallel configuration; this is able to enhance the pumping performance and compensate for the nonlinearity of coil sensor. The IPMC actuator was precisely manipulated by a repetitive controller which exhibited a better performance than another adaptive controller, PID with IFT (iterative feedback tuning), in terms of error, control effort and computational resource. This pump is, to the authors’ knowledge, the first IPMC driven double-chamber valveless pump developed to date and has validated that the entire pump has a maximum pumping rate of 766μL/min which is sufficient for most biomedical applications. By successfully developing the valveless pump prototype with scalable components in this research the feasibility of integrating such valveless pumps into further biomedical applications has been proven. en
dc.publisher ResearchSpace@Auckland en
dc.relation.ispartof PhD Thesis - University of Auckland en
dc.relation.isreferencedby UoA99265056013602091 en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. en
dc.rights.uri en
dc.rights.uri en
dc.title An IPMC Driven Valveless Pump for Biomedical Applications en
dc.type Thesis en Mechatronics en The University of Auckland en Doctoral en PhD en
dc.rights.holder Copyright: The author en
dc.rights.accessrights en
pubs.elements-id 628916 en
pubs.record-created-at-source-date 2017-06-08 en

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