Individually released polystyrene-platinum bimorph microcantilevers that have potential applicati... more Individually released polystyrene-platinum bimorph microcantilevers that have potential applications as MEMS/NEMS thermal actuators are produced using focused ion beam micromachining technique. The microcantilevers are sharply defined and triangular in cross-section, and are about 20µm long, 2 µm wide and 1.5 µm thick. The fabrication process is fast (< 3 hours) and does not require any mask or resist. The nanometer-scale displacement of the resulting bimorph microactuator with respect to temperature change is recorded via imaging in a scanning electron microscope, equipped with a heating stage. By increasing the temperature to ca. 55 °C, a tip deflection of ca. 380 nm was measured. This result is compared with the numerical result obtained from a finite element analysis (FEA).
... an electro-chemical reaction [2]. While most EAP actuators have been synthesised to operate i... more ... an electro-chemical reaction [2]. While most EAP actuators have been synthesised to operate in liquid electrolytes for numerous biomedical uses [3] and [4], multi-layer EAP actuators prepared by separating two electroactive polymer (PPy) films by an insulating soft, porous film ...
This paper reports on the prediction of the expected positioning errors of robot manipulators due... more This paper reports on the prediction of the expected positioning errors of robot manipulators due to the errors in their geometric parameters. A Swarm Intelligence (SI) based algorithm, which is known as Particle Swarm Optimization (PSO), has been used to generate error estimation functions. The experimental system used is a Motoman SK120 manipulator. The error estimation functions are based on the robot position data provided by a high precision laser measurement system. The functions have been verified for three test trajectories, which contain various configurations of the manipulator. The experimental results demonstrate that the positioning errors of robot manipulators can be effectively predicted using some constant coefficient polynomials whose coefficients are determined by employing the PSO algorithm. It must be emphasized that once the estimation functions are obtained, there may be no need of any further experimental data in order to determine the expected positioning errors for a subsequent use in the error correction process.
In the past, adaptive tuned vibration absorbers (ATVAs) based on magnetorheological elastomers (M... more In the past, adaptive tuned vibration absorbers (ATVAs) based on magnetorheological elastomers (MREs) have mainly been developed in a shear working mode. The enhancing effect of MREs in squeeze mode has already been investigated, but ATVAs in squeeze mode have rarely been studied. This paper reports the development of a compact squeeze MRE absorber and its subsequent performance in various magnetic fields characterized under various frequencies by a vibration testing system. The results revealed that the natural frequency of the MRE absorber working in squeeze mode can be tuned from 37 Hz to 67 Hz. Following this, a theoretical model based on magnetic dipole theory was developed to investigate the dynamic performance of the squeeze MRE absorber, and the vibration attenuation of the squeeze MRE absorber was then verified by mounting it on a beam with supports under both ends. The results revealed that the squeeze MRE absorber extended its vibration attenuation range from 37 Hz to 67 Hz while the passive absorber was only effective around 53 Hz.
Magneto-rheological elastomers (MREs) have attracted notable credits in the development of smart ... more Magneto-rheological elastomers (MREs) have attracted notable credits in the development of smart isolators and absorbers due to their controllable stiffness and damping properties. For the purpose of mitigating unwanted structural and/or machinery vibrations, the traditional MRE-based isolators have been generally proven effective because the MR effect can increase the stiffness when the magnetic field is strengthened. This study presents a novel MRE isolator that experienced reduced stiffness when the applied current was increased. This innovative work was accomplished by applying a hybrid magnet (electromagnet and permanent magnets) onto a multilayered MRE structure. To characterise this negative changing stiffness concept, a multilayered MRE isolator with a hybrid magnet was first designed, fabricated and then tested to measure its properties. An obvious reduction of the effective stiffness and natural frequency of the proposed MRE isolator occurred when the current was continuously adjusted. This device could also work as a conventional MRE isolator as its effective stiffness and natural frequency also increased when a negative current was applied. Further testing was carried out on a one-degree-of-freedom system to assess how effectively this device could isolate vibration. In this experiment, two cases were considered; in each case, the vibration of the primary system was obviously attenuated under ON-OFF control logic, thus demonstrating the feasibility of this novel design as an alternative adaptive vibration isolator.
IEEE transactions on biomedical circuits and systems, Dec 14, 2017
In this paper, we proposed a microparticle manipulation approach, by which particles are able to ... more In this paper, we proposed a microparticle manipulation approach, by which particles are able to be guided to different equilibrium positions through modulating the Reynolds number. In the microchannel with arc-shaped groove arrays, secondary flow vortex arisen due to the pressure gradient varies in the aspects of both magnitude and shape with the increase of Reynolds number. And the variation of secondary flow vortex brings about different focusing modes of microparticles in the microchannel. We investigated the focusing phenomenon experimentally and analyzed the mechanism through numerical simulations. At a high Reynolds number (Re = 127.27), the geometry-induced secondary flow rotates constantly along a direction, and most particles are guided to the equilibrium position near one side of the microchannel. However, at a low Reynolds number (Re = 2.39), the shapes of geometry-induced secondary flow vortices are obviously different, forming a variant Dean-like vortex that consists o...
There has been a growing interest in smart actuators typified by conducting polymer actuators, es... more There has been a growing interest in smart actuators typified by conducting polymer actuators, especially in their (i) fabrication, modeling and control with minimum external data and (ii) applications in bio-inspired devices, robotics and mechatronics. Their control is a challenging research problem due to the complex and nonlinear properties of these actuators, which cannot be predicted accurately. Based on an input-shaping technique, we propose a new method to improve the conducting polymer actuators' command-following ability, while minimizing their electric power consumption. We applied four input functions with smooth characteristics to a trilayer conducting polymer actuator to experimentally evaluate its command-following ability under an open-loop control strategy and a simulated feedback control strategy, and, more importantly, to quantify how the type of input function affects the dynamic response of this class of actuators. We have found that the four smooth inputs consume less electrical power than sharp inputs such as a step input with discontinuous higher-order derivatives. We also obtained an improved transient response performance from the smooth inputs, especially under the simulated feedback control strategy, which we have proposed previously [X Xiang, R Mutlu, G Alici, and W Li, 2014 "Control of conducting polymer actuators without physical feedback: simulated feedback control approach with particle swarm optimization', Journal of Smart Materials and Structure, 23]. The idea of using a smooth input command, which results in lower power consumption and better control performance, can be extended to other smart actuators. Consuming less electrical energy or power will have a direct effect on enhancing the operational life of these actuators.
2014 IEEE/ASME International Conference on Advanced Intelligent Mechatronics, 2014
Electroactive Polymer actuators (EAPs), also known as EAP artificial muscles, offer a great poten... more Electroactive Polymer actuators (EAPs), also known as EAP artificial muscles, offer a great potential for soft robotics. They are suitable for bio-inspired robotic applications due to their built-in actuation property within the mechanical body. In this paper, we report on a fully compliant micro-stage with built-in actuation. It has been fabricated as one piece inspired from twining structures in nature. We have employed a soft robotic modeling approach and finite element modeling to predict the mechanical output of the stage as a function of the input voltage. Experiments were conducted under a range of electrical inputs (0.25-1.00 V). For a given electrical stimulus, the compliant mechanism results in a linear motion in the middle of the active compliant mechanism, as expected. Experiments and simulation results are in good correlation. The active compliant mechanism can be used as a micro stage as well as an optical zoom mechanism for mobile phone cameras and similar devices.
This paper presents the design and analysis of a new adaptive fuzzy (AF) logic and hybrid (skyhoo... more This paper presents the design and analysis of a new adaptive fuzzy (AF) logic and hybrid (skyhook plus groundhook) control technique applied to a semi-active suspension system of a quarter car mode. The hybrid control is applied because of its very good performance in ride comfort and road handling. Meanwhile, Fuzzy adaptive system is suitable for analysis of stability with non-linear performances. The adaptive fuzzy algorithm is used to approximate the estimated mass of the variable damping in the Hybrid loop. This model is adopting a Takagi-Sugeno configuration with a back propagation learning method typically used in a neural network configuration, which uses a product inference engine, singleton fuzzifier, centre average defuzzifier, and Gaussian membership function. Numerical simulations were conducted based on Simulink/Matlab using Fuzzy Logic Toolbox. It is found that the semi-active suspension system with the proposed adaptive fuzzyhybrid yields superior performance compared to both the Hybrid and the Passive counterparts.
Microfluidic diagnostic devices often require handling particles or cells with different sizes. I... more Microfluidic diagnostic devices often require handling particles or cells with different sizes. In this investigation, a tunable hydrophoretic device was developed which consists of a polydimethylsiloxane (PDMS) slab with hydrophoretic channel, a PDMS diaphragm with pressure channel, and a glass slide. The height of the hydrophoretic channel can be tuned simply and reliably by deforming the elastomeric diaphragm with pressure applied on the pressure channel. This operation allows the device to have a large operating range where different particles and complex biological samples can be processed. The focusing performance of this device was tested using blood cells that varied in shape and size. The hydrophoretic channel had a large cross section which enabled a throughput capability for cell focusing of $15 000 cells s À1 , which was more than the conventional hydrophoretic focusing and dielectrophoresis (DEP)-active hydrophoretic methods. This tunable hydrophoretic focuser can potentially be integrated into advanced lab-on-a-chip bioanalysis devices. V
Plasma is a complex substance that contains proteins and circulating nucleic acids and viruses th... more Plasma is a complex substance that contains proteins and circulating nucleic acids and viruses that can be utilised for clinical diagnostics, albeit a precise analysis depends on the plasma being totally free of cells. We proposed the use of a dielectrophoresis (DEP)-active hydrophoretic method to isolate plasma from blood in a high-throughput manner. This microfluidic device consists of anisotropic microstructures embedded on the top of the channel which generate lateral pressure gradients while interdigitised electrodes lay on the bottom of the channel which can push particles or cells into a higher level using a negative DEP force. Large and small particles or cells (3 μm and 10 μm particles, and red blood cells, white blood cells, and platelets) can be focused at the same time in our DEP-active hydrophoretic device at an appropriate flow rate and applied voltage. Based on this principle, all the blood cells were filtrated from whole blood and then the plasma was extracted with a purity of 94.2% and a yield of 16.5% at a flow rate of 10 μL min−1. This solved the challenging problem caused by the relatively low throughput of the DEP based device. Our DEP-active hydrophoretic device is a flexible and tunable system that can control the lateral positions of particles by modulating the external voltages without redesigning and fabricating a new channel, and because it is easy to operate, it is easily compatible with other microfluidic platforms that are used for further detection.
IEEE/ASME International Conference on Advanced Intelligent Mechatronics, AIM, 2012
Kinematic analysis of electroactive polymer actuators as soft and smart Kinematic analysis of ele... more Kinematic analysis of electroactive polymer actuators as soft and smart Kinematic analysis of electroactive polymer actuators as soft and smart structures with more DoF than inputs structures with more DoF than inputs
2013 IEEE/ASME International Conference on Advanced Intelligent Mechatronics: Mechatronics for Human Wellbeing, AIM 2013, 2013
Centrifuge-on-a-chip" is a versatile and multifunctional microfluidic chip which can conduct oper... more Centrifuge-on-a-chip" is a versatile and multifunctional microfluidic chip which can conduct operations of selective trapping, enrichment, labeling and solution exchange. In this work, the mechanism of selective trapping ability was studied by both the experiments and numerical simulation. We proved the existence of shear gradient lift force in the expansion-contraction cavity and derived an explicit expression of it. Also, a numerical modeling was developed to study the trapping process of micro-particles in a "Centrifuge-on-achip". The effects of flow condition and particle size on the trapping process were investigated. It demonstrates that the derived expression and developed model are suitable for the prediction of particles' trapping process, which can assist the design of "Centrifuge-on-a-chip".
In this paper, we report the development of a simple inertial microfluidic device with serpentine... more In this paper, we report the development of a simple inertial microfluidic device with serpentine channel for efficiently separating blood cells from plasma. The working mechanism of this device relies on the two-sided secondary flow aided inertial focusing of particles in a serpentine channel. Specifically, blood cells were focused along two sides of channel, while the blood plasma was collected at the cell-free region within the channel centre. The device was tested with diluted (1/20) whole blood. A relatively high flow rate of 350 μl/min with a purity of ~99.75% was achieved in a single process. A further improvement to 99.95% purity was obtained after a second process. Parallelization with eight parallel serpentine channels achieved a high flow rate of 2.8 ml/min and a massive throughput of 7×10 8 cells/min. Our device could be easily integrated with other sample preparation processes or detection units to form a sample-to-answer lab-on-a-chip system.
This paper proposes a novel concept of dielectrophoresis (DEP)-active hydrophoretic focusing of m... more This paper proposes a novel concept of dielectrophoresis (DEP)-active hydrophoretic focusing of micro-particles and murine erythroleukemia (MEL) cells. The DEP-active hydrophoretic platform consists of crescent shaped grooves and interdigitated electrodes that generate lateral pressure gradients. These embedded electrodes exert a negative DEP force onto the particles by pushing them into a narrow space in the channel where the particle to groove interaction is intensive and hydrophoretic ordering occurs. Particles passing through the microfluidic device are directed towards the sidewalls of the channel. The critical limitation of DEP operating at a low flow rate and the specific hydrophoretic device for focusing particles of given sizes were overcome with the proposed microfluidic device. The focusing pattern can be modulated by varying the voltage. High throughput was achieved (maximum flow rate ~150 μL min(-1)) with good focusing performance. The non-spherical MEL cells were utili...
In this work, we explored the possibility of combining dielectrophoresis (DEP) and inertial focus... more In this work, we explored the possibility of combining dielectrophoresis (DEP) and inertial focusing in a fully coupled manner and proposed a new concept, which is called DEP-inertial microfluidics. A vertical DEP force is used to tune the inertial focusing pattern and position in three dimensions.
High-throughput particle manipulation by hydrodynamic, electrokinetic, and dielectrophoretic effe... more High-throughput particle manipulation by hydrodynamic, electrokinetic, and dielectrophoretic effects in an integrated microfluidic chip Biomicrofluidics 7, 024106 (2013);
The wireless capsule endoscope (WCE) is a first-line medical tool for the diagnosis of many gastr... more The wireless capsule endoscope (WCE) is a first-line medical tool for the diagnosis of many gastrointestinal (GI) tract diseases such as obscure GI bleeding, Crohn's disease, small bowel tumors, and Celiac disease. Over the past few years, significant research attention has been paid to upgrading the WCE from a diagnostic-only tool to an active medical robot having not only diagnostic capabilities but therapeutic functionalities, such as biopsy, microsurgery, and targeted drug delivery, as well. One of the major limitations that impedes the development of such a robotic-type endoscope is the lack of a highly accurate localization system. In this paper, we present an experimental evaluation of a new real-time localization method (patent pending) based on tracking three positron emission markers embedded in the cover of an endoscopic capsule. Coincidence gamma rays emitted from the markers are detected by surrounding gamma ray detectors. The position and orientation information of the capsule can then be extracted by an effective tracking algorithm. The experiments were conducted in two different commercial positron emission technology (PET) scanners: Philips Allegro and Philips TF64. The experimental results show that the proposed localization method could provide less than 0.5-mm position error and 2.4° orientation error in a localization time interval of 50 ms with an average computational time of 6 ms per time interval. Zero power consumption and zero space occupation inside the capsule are additional advantages of this localization method.
2013 IEEE/ASME International Conference on Advanced Intelligent Mechatronics, 2013
Modeling and experimental investigation on the mechanical behavior of a Modeling and experimental... more Modeling and experimental investigation on the mechanical behavior of a Modeling and experimental investigation on the mechanical behavior of a spiral-type capsule in the small intestine spiral-type capsule in the small intestine
2012 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM), 2012
This paper reports on the magnetic propulsion of a spiral-type endoscopic mircorobot in a real sm... more This paper reports on the magnetic propulsion of a spiral-type endoscopic mircorobot in a real small intestine. Magnetic modeling was carried out to design and commission an external electromagnetic system, which wirelessly provides power to the robotic agent. The capsules with different spiral structures were magnetically propelled inside a segment of porcine small intestine. From the results, it is shown that the propulsive velocities of the tested capsules are in the range of 2.5 ~ 35 mm/s when rotating frequencies varying between 1 ~ 5 Hz are applied. Among all the capsules prepared for this study, the capsule No. 5, with one spiral and a helical angle of 20° and spiral height of 1 mm, shows the best performance. The effects of the spiral parameters, such as helical angle, number of spirals and spiral height, are evaluated by using the propulsion velocity and the slip ratio as the evaluation criteria.
Individually released polystyrene-platinum bimorph microcantilevers that have potential applicati... more Individually released polystyrene-platinum bimorph microcantilevers that have potential applications as MEMS/NEMS thermal actuators are produced using focused ion beam micromachining technique. The microcantilevers are sharply defined and triangular in cross-section, and are about 20µm long, 2 µm wide and 1.5 µm thick. The fabrication process is fast (< 3 hours) and does not require any mask or resist. The nanometer-scale displacement of the resulting bimorph microactuator with respect to temperature change is recorded via imaging in a scanning electron microscope, equipped with a heating stage. By increasing the temperature to ca. 55 °C, a tip deflection of ca. 380 nm was measured. This result is compared with the numerical result obtained from a finite element analysis (FEA).
... an electro-chemical reaction [2]. While most EAP actuators have been synthesised to operate i... more ... an electro-chemical reaction [2]. While most EAP actuators have been synthesised to operate in liquid electrolytes for numerous biomedical uses [3] and [4], multi-layer EAP actuators prepared by separating two electroactive polymer (PPy) films by an insulating soft, porous film ...
This paper reports on the prediction of the expected positioning errors of robot manipulators due... more This paper reports on the prediction of the expected positioning errors of robot manipulators due to the errors in their geometric parameters. A Swarm Intelligence (SI) based algorithm, which is known as Particle Swarm Optimization (PSO), has been used to generate error estimation functions. The experimental system used is a Motoman SK120 manipulator. The error estimation functions are based on the robot position data provided by a high precision laser measurement system. The functions have been verified for three test trajectories, which contain various configurations of the manipulator. The experimental results demonstrate that the positioning errors of robot manipulators can be effectively predicted using some constant coefficient polynomials whose coefficients are determined by employing the PSO algorithm. It must be emphasized that once the estimation functions are obtained, there may be no need of any further experimental data in order to determine the expected positioning errors for a subsequent use in the error correction process.
In the past, adaptive tuned vibration absorbers (ATVAs) based on magnetorheological elastomers (M... more In the past, adaptive tuned vibration absorbers (ATVAs) based on magnetorheological elastomers (MREs) have mainly been developed in a shear working mode. The enhancing effect of MREs in squeeze mode has already been investigated, but ATVAs in squeeze mode have rarely been studied. This paper reports the development of a compact squeeze MRE absorber and its subsequent performance in various magnetic fields characterized under various frequencies by a vibration testing system. The results revealed that the natural frequency of the MRE absorber working in squeeze mode can be tuned from 37 Hz to 67 Hz. Following this, a theoretical model based on magnetic dipole theory was developed to investigate the dynamic performance of the squeeze MRE absorber, and the vibration attenuation of the squeeze MRE absorber was then verified by mounting it on a beam with supports under both ends. The results revealed that the squeeze MRE absorber extended its vibration attenuation range from 37 Hz to 67 Hz while the passive absorber was only effective around 53 Hz.
Magneto-rheological elastomers (MREs) have attracted notable credits in the development of smart ... more Magneto-rheological elastomers (MREs) have attracted notable credits in the development of smart isolators and absorbers due to their controllable stiffness and damping properties. For the purpose of mitigating unwanted structural and/or machinery vibrations, the traditional MRE-based isolators have been generally proven effective because the MR effect can increase the stiffness when the magnetic field is strengthened. This study presents a novel MRE isolator that experienced reduced stiffness when the applied current was increased. This innovative work was accomplished by applying a hybrid magnet (electromagnet and permanent magnets) onto a multilayered MRE structure. To characterise this negative changing stiffness concept, a multilayered MRE isolator with a hybrid magnet was first designed, fabricated and then tested to measure its properties. An obvious reduction of the effective stiffness and natural frequency of the proposed MRE isolator occurred when the current was continuously adjusted. This device could also work as a conventional MRE isolator as its effective stiffness and natural frequency also increased when a negative current was applied. Further testing was carried out on a one-degree-of-freedom system to assess how effectively this device could isolate vibration. In this experiment, two cases were considered; in each case, the vibration of the primary system was obviously attenuated under ON-OFF control logic, thus demonstrating the feasibility of this novel design as an alternative adaptive vibration isolator.
IEEE transactions on biomedical circuits and systems, Dec 14, 2017
In this paper, we proposed a microparticle manipulation approach, by which particles are able to ... more In this paper, we proposed a microparticle manipulation approach, by which particles are able to be guided to different equilibrium positions through modulating the Reynolds number. In the microchannel with arc-shaped groove arrays, secondary flow vortex arisen due to the pressure gradient varies in the aspects of both magnitude and shape with the increase of Reynolds number. And the variation of secondary flow vortex brings about different focusing modes of microparticles in the microchannel. We investigated the focusing phenomenon experimentally and analyzed the mechanism through numerical simulations. At a high Reynolds number (Re = 127.27), the geometry-induced secondary flow rotates constantly along a direction, and most particles are guided to the equilibrium position near one side of the microchannel. However, at a low Reynolds number (Re = 2.39), the shapes of geometry-induced secondary flow vortices are obviously different, forming a variant Dean-like vortex that consists o...
There has been a growing interest in smart actuators typified by conducting polymer actuators, es... more There has been a growing interest in smart actuators typified by conducting polymer actuators, especially in their (i) fabrication, modeling and control with minimum external data and (ii) applications in bio-inspired devices, robotics and mechatronics. Their control is a challenging research problem due to the complex and nonlinear properties of these actuators, which cannot be predicted accurately. Based on an input-shaping technique, we propose a new method to improve the conducting polymer actuators' command-following ability, while minimizing their electric power consumption. We applied four input functions with smooth characteristics to a trilayer conducting polymer actuator to experimentally evaluate its command-following ability under an open-loop control strategy and a simulated feedback control strategy, and, more importantly, to quantify how the type of input function affects the dynamic response of this class of actuators. We have found that the four smooth inputs consume less electrical power than sharp inputs such as a step input with discontinuous higher-order derivatives. We also obtained an improved transient response performance from the smooth inputs, especially under the simulated feedback control strategy, which we have proposed previously [X Xiang, R Mutlu, G Alici, and W Li, 2014 "Control of conducting polymer actuators without physical feedback: simulated feedback control approach with particle swarm optimization', Journal of Smart Materials and Structure, 23]. The idea of using a smooth input command, which results in lower power consumption and better control performance, can be extended to other smart actuators. Consuming less electrical energy or power will have a direct effect on enhancing the operational life of these actuators.
2014 IEEE/ASME International Conference on Advanced Intelligent Mechatronics, 2014
Electroactive Polymer actuators (EAPs), also known as EAP artificial muscles, offer a great poten... more Electroactive Polymer actuators (EAPs), also known as EAP artificial muscles, offer a great potential for soft robotics. They are suitable for bio-inspired robotic applications due to their built-in actuation property within the mechanical body. In this paper, we report on a fully compliant micro-stage with built-in actuation. It has been fabricated as one piece inspired from twining structures in nature. We have employed a soft robotic modeling approach and finite element modeling to predict the mechanical output of the stage as a function of the input voltage. Experiments were conducted under a range of electrical inputs (0.25-1.00 V). For a given electrical stimulus, the compliant mechanism results in a linear motion in the middle of the active compliant mechanism, as expected. Experiments and simulation results are in good correlation. The active compliant mechanism can be used as a micro stage as well as an optical zoom mechanism for mobile phone cameras and similar devices.
This paper presents the design and analysis of a new adaptive fuzzy (AF) logic and hybrid (skyhoo... more This paper presents the design and analysis of a new adaptive fuzzy (AF) logic and hybrid (skyhook plus groundhook) control technique applied to a semi-active suspension system of a quarter car mode. The hybrid control is applied because of its very good performance in ride comfort and road handling. Meanwhile, Fuzzy adaptive system is suitable for analysis of stability with non-linear performances. The adaptive fuzzy algorithm is used to approximate the estimated mass of the variable damping in the Hybrid loop. This model is adopting a Takagi-Sugeno configuration with a back propagation learning method typically used in a neural network configuration, which uses a product inference engine, singleton fuzzifier, centre average defuzzifier, and Gaussian membership function. Numerical simulations were conducted based on Simulink/Matlab using Fuzzy Logic Toolbox. It is found that the semi-active suspension system with the proposed adaptive fuzzyhybrid yields superior performance compared to both the Hybrid and the Passive counterparts.
Microfluidic diagnostic devices often require handling particles or cells with different sizes. I... more Microfluidic diagnostic devices often require handling particles or cells with different sizes. In this investigation, a tunable hydrophoretic device was developed which consists of a polydimethylsiloxane (PDMS) slab with hydrophoretic channel, a PDMS diaphragm with pressure channel, and a glass slide. The height of the hydrophoretic channel can be tuned simply and reliably by deforming the elastomeric diaphragm with pressure applied on the pressure channel. This operation allows the device to have a large operating range where different particles and complex biological samples can be processed. The focusing performance of this device was tested using blood cells that varied in shape and size. The hydrophoretic channel had a large cross section which enabled a throughput capability for cell focusing of $15 000 cells s À1 , which was more than the conventional hydrophoretic focusing and dielectrophoresis (DEP)-active hydrophoretic methods. This tunable hydrophoretic focuser can potentially be integrated into advanced lab-on-a-chip bioanalysis devices. V
Plasma is a complex substance that contains proteins and circulating nucleic acids and viruses th... more Plasma is a complex substance that contains proteins and circulating nucleic acids and viruses that can be utilised for clinical diagnostics, albeit a precise analysis depends on the plasma being totally free of cells. We proposed the use of a dielectrophoresis (DEP)-active hydrophoretic method to isolate plasma from blood in a high-throughput manner. This microfluidic device consists of anisotropic microstructures embedded on the top of the channel which generate lateral pressure gradients while interdigitised electrodes lay on the bottom of the channel which can push particles or cells into a higher level using a negative DEP force. Large and small particles or cells (3 μm and 10 μm particles, and red blood cells, white blood cells, and platelets) can be focused at the same time in our DEP-active hydrophoretic device at an appropriate flow rate and applied voltage. Based on this principle, all the blood cells were filtrated from whole blood and then the plasma was extracted with a purity of 94.2% and a yield of 16.5% at a flow rate of 10 μL min−1. This solved the challenging problem caused by the relatively low throughput of the DEP based device. Our DEP-active hydrophoretic device is a flexible and tunable system that can control the lateral positions of particles by modulating the external voltages without redesigning and fabricating a new channel, and because it is easy to operate, it is easily compatible with other microfluidic platforms that are used for further detection.
IEEE/ASME International Conference on Advanced Intelligent Mechatronics, AIM, 2012
Kinematic analysis of electroactive polymer actuators as soft and smart Kinematic analysis of ele... more Kinematic analysis of electroactive polymer actuators as soft and smart Kinematic analysis of electroactive polymer actuators as soft and smart structures with more DoF than inputs structures with more DoF than inputs
2013 IEEE/ASME International Conference on Advanced Intelligent Mechatronics: Mechatronics for Human Wellbeing, AIM 2013, 2013
Centrifuge-on-a-chip" is a versatile and multifunctional microfluidic chip which can conduct oper... more Centrifuge-on-a-chip" is a versatile and multifunctional microfluidic chip which can conduct operations of selective trapping, enrichment, labeling and solution exchange. In this work, the mechanism of selective trapping ability was studied by both the experiments and numerical simulation. We proved the existence of shear gradient lift force in the expansion-contraction cavity and derived an explicit expression of it. Also, a numerical modeling was developed to study the trapping process of micro-particles in a "Centrifuge-on-achip". The effects of flow condition and particle size on the trapping process were investigated. It demonstrates that the derived expression and developed model are suitable for the prediction of particles' trapping process, which can assist the design of "Centrifuge-on-a-chip".
In this paper, we report the development of a simple inertial microfluidic device with serpentine... more In this paper, we report the development of a simple inertial microfluidic device with serpentine channel for efficiently separating blood cells from plasma. The working mechanism of this device relies on the two-sided secondary flow aided inertial focusing of particles in a serpentine channel. Specifically, blood cells were focused along two sides of channel, while the blood plasma was collected at the cell-free region within the channel centre. The device was tested with diluted (1/20) whole blood. A relatively high flow rate of 350 μl/min with a purity of ~99.75% was achieved in a single process. A further improvement to 99.95% purity was obtained after a second process. Parallelization with eight parallel serpentine channels achieved a high flow rate of 2.8 ml/min and a massive throughput of 7×10 8 cells/min. Our device could be easily integrated with other sample preparation processes or detection units to form a sample-to-answer lab-on-a-chip system.
This paper proposes a novel concept of dielectrophoresis (DEP)-active hydrophoretic focusing of m... more This paper proposes a novel concept of dielectrophoresis (DEP)-active hydrophoretic focusing of micro-particles and murine erythroleukemia (MEL) cells. The DEP-active hydrophoretic platform consists of crescent shaped grooves and interdigitated electrodes that generate lateral pressure gradients. These embedded electrodes exert a negative DEP force onto the particles by pushing them into a narrow space in the channel where the particle to groove interaction is intensive and hydrophoretic ordering occurs. Particles passing through the microfluidic device are directed towards the sidewalls of the channel. The critical limitation of DEP operating at a low flow rate and the specific hydrophoretic device for focusing particles of given sizes were overcome with the proposed microfluidic device. The focusing pattern can be modulated by varying the voltage. High throughput was achieved (maximum flow rate ~150 μL min(-1)) with good focusing performance. The non-spherical MEL cells were utili...
In this work, we explored the possibility of combining dielectrophoresis (DEP) and inertial focus... more In this work, we explored the possibility of combining dielectrophoresis (DEP) and inertial focusing in a fully coupled manner and proposed a new concept, which is called DEP-inertial microfluidics. A vertical DEP force is used to tune the inertial focusing pattern and position in three dimensions.
High-throughput particle manipulation by hydrodynamic, electrokinetic, and dielectrophoretic effe... more High-throughput particle manipulation by hydrodynamic, electrokinetic, and dielectrophoretic effects in an integrated microfluidic chip Biomicrofluidics 7, 024106 (2013);
The wireless capsule endoscope (WCE) is a first-line medical tool for the diagnosis of many gastr... more The wireless capsule endoscope (WCE) is a first-line medical tool for the diagnosis of many gastrointestinal (GI) tract diseases such as obscure GI bleeding, Crohn's disease, small bowel tumors, and Celiac disease. Over the past few years, significant research attention has been paid to upgrading the WCE from a diagnostic-only tool to an active medical robot having not only diagnostic capabilities but therapeutic functionalities, such as biopsy, microsurgery, and targeted drug delivery, as well. One of the major limitations that impedes the development of such a robotic-type endoscope is the lack of a highly accurate localization system. In this paper, we present an experimental evaluation of a new real-time localization method (patent pending) based on tracking three positron emission markers embedded in the cover of an endoscopic capsule. Coincidence gamma rays emitted from the markers are detected by surrounding gamma ray detectors. The position and orientation information of the capsule can then be extracted by an effective tracking algorithm. The experiments were conducted in two different commercial positron emission technology (PET) scanners: Philips Allegro and Philips TF64. The experimental results show that the proposed localization method could provide less than 0.5-mm position error and 2.4° orientation error in a localization time interval of 50 ms with an average computational time of 6 ms per time interval. Zero power consumption and zero space occupation inside the capsule are additional advantages of this localization method.
2013 IEEE/ASME International Conference on Advanced Intelligent Mechatronics, 2013
Modeling and experimental investigation on the mechanical behavior of a Modeling and experimental... more Modeling and experimental investigation on the mechanical behavior of a Modeling and experimental investigation on the mechanical behavior of a spiral-type capsule in the small intestine spiral-type capsule in the small intestine
2012 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM), 2012
This paper reports on the magnetic propulsion of a spiral-type endoscopic mircorobot in a real sm... more This paper reports on the magnetic propulsion of a spiral-type endoscopic mircorobot in a real small intestine. Magnetic modeling was carried out to design and commission an external electromagnetic system, which wirelessly provides power to the robotic agent. The capsules with different spiral structures were magnetically propelled inside a segment of porcine small intestine. From the results, it is shown that the propulsive velocities of the tested capsules are in the range of 2.5 ~ 35 mm/s when rotating frequencies varying between 1 ~ 5 Hz are applied. Among all the capsules prepared for this study, the capsule No. 5, with one spiral and a helical angle of 20° and spiral height of 1 mm, shows the best performance. The effects of the spiral parameters, such as helical angle, number of spirals and spiral height, are evaluated by using the propulsion velocity and the slip ratio as the evaluation criteria.
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Papers by gursel alici