Elbuken Research Group
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  • H. Guner, E. Ozgur, G. Kokturk, M. Celik, E. Esen, A. E. Topal, S. Ayas, Y. Uludag, C. Elbuken and A. Dana, “A smartphone based surface plasmon resonance imaging (SPRi) platform for on-site biodetection,” Sens. Actuators B, v. 239, p. 571–577, Feb 2017 [link]. DOI: 10.1016/j.snb.2016.08.061 [pdf]
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      We demonstrate a surface plasmon resonance imaging platform integrated with a  smartphone to be used in the field with high-throughput biodetection. Inexpensive and disposable SPR substrates are produced by metal coating of commercial Blu-ray discs. A compact imaging apparatus is fabricated using a 3D printer which allows taking SPR measurements from more than 20.000 individual pixels. Real-time bulk refractive index change measurements yield noise equivalent refractive index changes as low as 4.12 × 10−5 RIU which is comparable with the detection performance of commercial instruments. As a demonstration of a biological assay, we have shown capture of mouse IgG antibodies by immobilized layer of rabbit anti-mouse (RAM) IgG antibody with nanomolar level limit of detection. Our approach in miniaturization of SPR biosensing in a cost-effective manner could enable realization of portable SPR measurement systems and kits for point-of-care applications.

    Z. Isiksacan, O. Erel and C. Elbuken, “A portable microfluidic system for rapid measurement of the erythrocyte sedimentation rate,” Lab Chip, v. 24, p. 4682–4690, Nov 2016 (cover article) [link]. DOI: 10.1039/c6lc01036a [pdf]
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      The erythrocyte sedimentation rate (ESR) is a frequently used 30 min or 60 min clinical test for screening of several inflammatory conditions, infections, trauma, and malignant diseases, as well as non-inflammatory conditions including prostate cancer and stroke. Erythrocyte aggregation (EA) is a physiological process where erythrocytes form face-to-face linear structures, called rouleaux, at stasis or low shear rates. In this work, we proposed a method for ESR measurement from EA. We developed a microfluidic opto-electro-mechanical system, using which we experimentally showed a significant correlation (R2 = 0.86) between ESR and EA. The microfluidic system was shown to measure ESR from EA using fingerprick blood in 2 min. 40 μl of whole blood is filled in a disposable polycarbonate cartridge which is illuminated with a near infrared emitting diode. Erythrocytes were disaggregated under the effect of a mechanical shear force using a solenoid pinch valve. Following complete disaggregation, transmitted light through the cartridge was measured using a photodetector for 1.5 min. The intensity level is at its lowest at complete disaggregation and highest at complete aggregation. We calculated ESR from the transmitted signal profile. We also developed another microfluidic cartridge specifically for monitoring the EA process in real-time during ESR measurement. The presented system is suitable for ultrafast, low-cost, and low-sample volume measurement of ESR at the point-of-care.

    M. Kanik, M. Marcali, M. Yunusa, C. Elbuken and M. Bayindir, “Continuous Triboelectric Power Harvesting and Biochemical Sensing Inside Poly(vinylidene fluoride) Hollow Fibers Using Microfluidic Droplet Generation,” Adv. Mater. Technol., 1600190, Nov 2016 [link] DOI:10.1002/admt.201600190 [pdf]
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      Triboelectric power harvesting and biochemical sensing inside poly(vinylidene fluoride) hollow fibers. Fiber-based microfluidic energy harvesting system, which is also utilized as self-powered chemical and biosensor. In vitro device concept demonstrating that triboelectric effect can be used for cell detection.

    M. Serhatlioglu, B. Ortac, C. Elbuken, N. Biyikli and M. E. Solmaz, “CO2 laser polishing of microfluidic channels fabricated by femtosecond laser assisted carving,” J. Micromech. Microeng., v. 26, p. 115011, Oct 2016 [link] DOI:10.1088/0960-1317/26/11/115011 [pdf]
    • show abstract

      We demonstrate a surface plasmon resonance imaging platform integrated with a  smartphone to be used in the field with high-throughput biodetection. Inexpensive and disposable SPR substrates are produced by metal coating of commercial Blu-ray discs. A compact imaging apparatus is fabricated using a 3D printer which allows taking SPR measurements from more than 20.000 individual pixels. Real-time bulk refractive index change measurements yield noise equivalent refractive index changes as low as 4.12 × 10−5 RIU which is comparable with the detection performance of commercial instruments. As a demonstration of a biological assay, we have shown capture of mouse IgG antibodies by immobilized layer of rabbit anti-mouse (RAM) IgG antibody with nanomolar level limit of detection. Our approach in miniaturization of SPR biosensing in a cost-effective manner could enable realization of portable SPR measurement systems and kits for point-of-care applications.

    P. Beyazkilic, U. Tuvshindorj, A. Yildirim, C. Elbuken and M. Bayindir, “Robust superhydrophilic patterning of superhydrophobic ormosil surfaces for high throughput on-chip screening applications,” RSC Advances, v. 6, p. 80049-80054, Aug 2016 [link]. DOI:  10.1039/c6ra19669a. [pdf]
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      Droplet-based microfluidic systems offer tremendous benefits for high throughput biochemical assays. Despite the wide use of electrical detection for microfluidic systems, application of impedimetric sensing for droplet systems is very limited. This is mainly due to the insulating oil-based continuous phase used for most aqueous samples of interest. We present modelling and experimental verification of impedimetric detection of hemagglutination in microdroplets. We have detected agglutinated red blood cells in microdroplets and screened whole blood samples for multiple antibody sera using conventional microelectrodes. We were able to form antibody and whole blood microdroplets in PDMS microchannels without any tedious chemical surface treatment. Following the injection of a blood sample into antibody droplets, we have detected the agglutination-positive and negative droplets in an automated manner. In order to understand the characteristics of impedimetric detection inside microdroplets, we have developed the lumped electrical circuit equivalent of an impedimetric droplet content detection system. The empirical lumped element values are in accordance with similar models developed for single phase electrical impedance spectroscopy systems. The presented approach is of interest for label-free, quantitative analysis of droplets. In addition, the standard electronic equipment used for detection allows miniaturized detection circuitries that can be integrated with a fluidic system for a quantitative microdroplet-based hemagglutination assay that is conventionally performed in well plates.

    M. Marcali and C. Elbuken, “Impedimetric detection and lumped element modelling of a hemagglutination assay in microdroplets,” Lab Chip, v. 16, pp. 2494-2503, May 2016 [link]. DOI: 10.1039/c6lc00623j [pdf]
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      Droplet-based microfluidic systems offer tremendous benefits for high throughput biochemical assays. Despite the wide use of electrical detection for microfluidic systems, application of impedimetric sensing for droplet systems is very limited. This is mainly due to the insulating oil-based continuous phase used for most aqueous samples of interest. We present modelling and experimental verification of impedimetric detection of hemagglutination in microdroplets. We have detected agglutinated red blood cells in microdroplets and screened whole blood samples for multiple antibody sera using conventional microelectrodes. We were able to form antibody and whole blood microdroplets in PDMS microchannels without any tedious chemical surface treatment. Following the injection of a blood sample into antibody droplets, we have detected the agglutination-positive and negative droplets in an automated manner. In order to understand the characteristics of impedimetric detection inside microdroplets, we have developed the lumped electrical circuit equivalent of an impedimetric droplet content detection system. The empirical lumped element values are in accordance with similar models developed for single phase electrical impedance spectroscopy systems. The presented approach is of interest for label-free, quantitative analysis of droplets. In addition, the standard electronic equipment used for detection allows miniaturized detection circuitries that can be integrated with a fluidic system for a quantitative microdroplet-based hemagglutination assay that is conventionally performed in well plates.

    Z. Isiksacan, M. T. Guler, B. Aydogdu, I. Bilican and C. Elbuken, “Rapid fabrication of microfluidic PDMS devices from reusable PDMS molds using laser ablation,”  J. Micromech. Microeng., v. 26, p. 035008, Feb 2016 [link] DOI:10.1088/0960-1317/26/3/035008 [pdf]
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      The conventional fabrication methods for microfluidic devices require cleanroom processes that are costly and time-consuming. We present a novel, facile, and low-cost method for rapid fabrication of polydimethylsiloxane (PDMS) molds and devices. The method consists of three main fabrication steps: female mold (FM), male mold (MM), and chip fabrication. We use a CO2 laser cutter to pattern a thin, spin-coated PDMS layer for FM fabrication. We then obtain reusable PDMS MM from the FM using PDMS/PDMS casting. Finally, a second casting step is used to replicate PDMS devices from the MM. Demolding of one PDMS layer from another is carried out without any potentially hazardous chemical surface treatment. We have successfully demonstrated that this novel method allows fabrication of microfluidic molds and devices with precise dimensions (thickness, width, length) using a single material, PDMS, which is very common across microfluidic laboratories. The whole process, from idea to device testing, can be completed in 1.5 h in a standard laboratory.

    M. T. Guler, I. Bilican, S. Agan and C. Elbuken, “A simple approach for the fabrication of 3D microelectrodes for impedimetric sensing,”  J. Micromech. Microeng., v. 25, p. 095019, Aug 2015 [link]. DOI:10.1088/0960-1317/25/9/095019 [pdf]
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      In this paper, we present a very simple method to fabricate three-dimensional (3D) microelectrodes integrated with microfluidic devices. We form the electrodes by etching a microwire placed across a microchannel. For precise control of the electrode spacing, we employ a hydrodynamic focusing microfluidic device and control the width of the etching solution stream. The focused widths of the etchant solution and the etching time determine the gap formed between the electrodes. Using the same microfluidic device, we can fabricate integrated 3D electrodes with different electrode gaps. We have demonstrated the functionality of these electrodes using an impedimetric particle counting setup. Using 3D microelectrodes with a diameter of 25 μm, we have detected 6 μm-diameter polystyrene beads in a buffer solution as well as erythrocytes in a PBS solution. We study the effect of electrode spacing on the signalto-noise ratio of the impedance signal and we demonstrate that the smaller the electrode spacing the higher the signal obtained from a single microparticle. The sample stream is introduced to the system using the same hydrodynamic focusing device, which ensures the alignment of the sample in between the electrodes. Utilising a 3D hydrodynamic focusing approach, we force all the particles to go through the sensing region of the electrodes. This fabrication scheme not only provides a very low-cost and easy method for rapid prototyping, but which can also be used for applications requiring 3D electric field focused through a narrow section of the microchannel.

    P. K. Isgor, M. Marcali, M. Keser and C. Elbuken, “Microfluidic droplet content detection using integrated capacitive sensors,”  Sens. Actuators B, v. 210, p. 669-675, Jan 2015 [link] DOI:10.1016/j.snb.2015.01.018 [pdf]
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      Microfluidic capacitive sensors have been used for detection of droplets, however they have been lacking the sensitivity required for detecting the content of droplets. In this study, we developed a scalable, portable, robust and  high sensitivity capacitive microdroplet content detection system using coplanar electrodes with nanometer thick silicon dioxide (SiO2) passivation layer and off-the-shelf capacitive sensors. The microfluidic chip we have designed provides easy and rapid modification of droplet content by mixing two aqueous liquids at any given ratio. The change in dielectric constant of the droplet content leads to the change in capacitive signal. The dielectric content of droplets was modified continuously while corresponding capacitance signal was measured. The resolution of the system was measured as 3 dielectric permittivity units. The results were verified using a semiconductor parameter analyzer. The application specific integrated circuit used in this work enables a portable, low-cost detection system and matches the performance of bench-top analyzers. Automated and precise measurement of dielectric content in droplets for biochemical assay monitoring is a major application of the presented system.

    O. Cakmak, C. Elbuken, E. Ermek,  A. Mostafazadeh,  I. Baris,  B. E. Alaca,  I.H. Kavakli and H. Urey, “Microcantilever based blood plasma viscosity sensor,”  Elsevier Methods, v. 63, issue 3, p. 225-232, Oct. 2013 (cover article)  [link]  DOI:10.1016/j.ymeth.2013.07.009 [pdf]
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      This paper proposes a novel method for measuring blood plasma and serum viscosity with a microcantilever-based MEMS sensor. MEMS cantilevers are made of electroplated nickel and actuated remotely with magnetic field using an electro-coil. Real-time monitoring of cantilever resonant frequency is performed remotely using diffraction gratings fabricated at the tip of the dynamic cantilevers. Only few nanometer cantilever deflection is sufficient due to interferometric sensitivity of the readout. The resonant frequency of the cantilever is tracked with a phase lock loop (PLL) control circuit. The viscosities of liquid samples are obtained through the measurement of the cantilever’s frequency change with respect to a reference measurement taken within a liquid of known viscosity. We performed measurements with glycerol solutions at different temperatures and validated the repeatability of the system by comparing with a reference commercial viscometer. Experimental results are compared with the theoretical predictions based on Sader’s theory and agreed reasonably well. Afterwards viscosities of different Fetal Bovine Serum and Bovine Serum Albumin mixtures are measured both at 23 °C and 37 °C, body temperature. Finally the viscosities of human blood plasma samples taken from healthy donors are measured. The proposed method is capable of measuring viscosities from 0.86 cP to 3.02 cP, which covers human blood plasma viscosity range, with a resolution better than 0.04 cP. The sample volume requirement is less than 150 μl and can be reduced significantly with optimized cartridge design. Both the actuation and sensing are carried out remotely, which allows for disposable sensor cartridges.

     T. Glawdel, C. Elbuken and  C. L. Ren, “Droplet formation in microfluidics T-junction generators operating in the transitional regime. II – Modelling,” Phy. Review E, v. 85, issue 1, p. 016323, Jan. 2012 [link] DOI: 10.1103/PhysRevE.85.016323 [pdf]
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      This is the second part of a two-part study on the generation of droplets at a microfluidic T-junction operating in the transition regime. In the preceding paper [Phys. Rev. E 85, 016322 (2012)], we presented our experimental observations of droplet formation and decomposed the process into three sequential stages defined as the lag, filling, and necking stages. Here we develop a model that describes the performance of microfluidic T-junction generators working in the squeezing to transition regimes where confinement of the droplet dominates the formation process. The model incorporates a detailed geometric description of the drop shape during the formation process combined with a force balance and necking criteria to define the droplet size, production rate, and spacing. The model inherently captures the influence of the intersection geometry, including the channel width ratio and height-to-width ratio, capillary number, and flow ratio, on the performance of the generator. The model is validated by comparing it to speed videos of the formation process for several T-junction geometries across a range of capillary numbers and viscosity ratios.

     T. Glawdel, C. Elbuken and  C. L. Ren, “Droplet formation in microfluidics T-junction generators operating in the transitional regime. I – Experimental observations,” Phy. Review E, v. 85, issue 1, p. 016322, Jan. 2012 [link]  DOI: 10.1103/PhysRevE.85.016322 [pdf]
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      This is the first part of a two-part study on the generation of droplets at a microfluidic T-junction operating in the transition regime where confinement of the droplet creates a large squeezing pressure that influences droplet formation. In this regime, the operation of the T-junction depends on the geometry of the intersection (height-to-width ratio, inlet width ratio), capillary number, flow ratio, and viscosity ratio of the two phases. Here in paper I we presented our experimental observations through the analysis of high-speed videos of the droplet formation process. Various parameters are tracked during the formation cycle such as the shape of the droplet (penetration depth and neck), interdroplet spacing, production rate, and flow of both phases across several T-junction designs and flow conditions. Generally, the formation process is defined by a two-stage model consisting of an initial filling stage followed by a necking stage. However, video evidence suggests the inclusion of a third stage, which we term the lag stage, at the beginning of the formation process that accounts for the retraction of the interface back into the injection channel after detachment. Based on the observations made in this paper, a model is developed to describe the formation process in paper II, which can be used to understand the design and operation of T-junction generators in the transition regime.

     C.  Elbuken, T. Glawdel, D. Chan, and  C. L. Ren, “Detection of microdroplet size and speed using capacitive sensors,”  Sens. Actuators A, v. 171, issue 2, pp. 55-62, Nov. 2011 [link]  DOI:10.1016/j.sna.2011.07.007 [pdf]
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      Detection of the presence, size and speed of microdroplets in microfluidic devices is presented using commercially available capacitive sensors which make the droplet based microfluidic systems scalable and inexpensive. Cross-contamination between the droplets is eliminated by introducing a passivation layer between the sensing electrodes and droplets. A simple T-junction generator is used to generate droplets in microchannels. Coplanar electrodes are used to form a capacitance through the microfluidic channel. The change in capacitance due to the presence of a droplet in the sensing area is detected and used to determine the size and speed of the droplet. The design of a single pair of electrodes is used to detect the presence of a droplet and the interdigital finger design is used to detect the size and speed of the droplet. An analytical model is developed to predict the detection signal and guide the experimental optimization of the sensor geometry. The measured droplet information is displayed through a Labview interface in real-time. The use of capacitance sensors to monitor droplet sorting at a T-junction is also presented. The discussions in this paper can be generalized to any droplet detection application and can serve as a guideline in sensor selection.

    T.  Glawdel, C. Elbuken and C. L. Ren, “Passive droplet trafficking at microfluidic junctions under geometric and flow asymmetries,” Lab Chip, v. 11, pp 3774-3784, Sep. 2011 (cover article) [link]  DOI: 10.1039/C1LC20628A [pdf]
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      When droplets enter a junction they sort to the channel with the highest flow rate at that instant.Transport is regulated by a discrete time-delayed feedback that results in a highly periodic behavior where specific patterns can continue to cycle indefinitely. Between these highly ordered regimes are chaotic structures where no pattern is evident. Here we develop a model that describes droplet sorting under various asymmetries: branch geometry (length, cross-section), droplet resistance and pressures. First, a model is developed based on the continuum assumption and then, with the assistance of numerical simulations, a discrete model is derived to predict the length and composition of the sorting pattern. Furthermore we derive all unique sequences that are possible for a given distribution and develop a preliminary estimation of why chaotic regimes form. The model is validated by comparing it to numerical simulations and results from microfluidic experiments in PDMS chips with good agreement.

    M. Shameli, C. Elbuken, J. Ou, C. L. Ren and J. Pawliszyn. “Fully integrated PDMS/SU-8/quartz microfluidic chip with a novel macroporous poly dimethylsiloxane (PDMS) membrane for isoelectric focusing of proteins using whole-channel imaging detection,” Electrophoresis, v. 32, pp 333-339, Feb. 2011 [link]  DOI 10.1002/elps.201000643 [pdf]
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      A fully integrated polydimethylsiloxane (PDMS)/modified PDMS membrane/SU-8/ quartz hybrid chip was developed for protein separation using isoelectric focusing (IEF) mechanism coupled with whole-channel imaging detection (WCID) method. This microfluidic chip integrates three components into one single chip: (i) modified PDMS membranes for separating electrolytes in the reservoirs from the sample in the microchannel and thus reducing pressure disturbance, (ii) SU-8 optical slit to block UV light (below 300 nm) outside the channel aiming to increase detection sensitivity, and (iii) injection and discharge capillaries for continuous operation. Integration of all these components on a single chip is challenging because it requires fabrication techniques for perfect bonding between different materials and is prone to leakage and blockage. This study has addressed all the challenges and presented a fully integrated chip, which is more robust with higher sensitivity than the previously developed IEF chips. This chip was tested by performing protein and pI marker separation. The separation results obtained in this chip were compared with that obtained in commercial cartridges. Sideby-side comparison validated the developed chip and fabrication techniques.

     B. Y. Yu, C. Elbuken, C. L. Ren and J. P. Huissoon, “Image processing and classification algorithm for yeast cell morphology in a microfluidic chip,”  J. of Biomedical Optics, v. 16(6), 066008, June 2011 (selected for Virtual Journal of Biological Physics Research) [link]  DOI:10.1117/1.3589100 [pdf]
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      The study of yeast cell morphology requires consistent identification of cell cycle phases based on cell bud size. A computer-based image processing algorithm is designed to automatically classify microscopic images of yeast cells in a microfluidic channel environment. The images were enhanced to reduce background noise, and a robust segmentation algorithm is developed to extract geometrical features including compactness, axis ratio, and bud size. The features are then used for classification, and the accuracy of various machine-learning classifiers is compared. The linear support vector machine, distance-based classification, and k-nearest-neighbor algorithm were the classifiers used in this experiment. The performance of the system under various illumination and focusing conditions were also tested. The results suggest it is possible to automatically classify yeast cells based on their morphological characteristics with noisy and low-contrast images.

     T.  Glawdel, C. Elbuken, C. L. Ren and L. E. J. Lee. “Microfluidic system with integrated electroosmotic pumps, concentration gradient generator and fish cell line (RTgill-W1) – towards water toxicity testing,” Lab Chip, v. 9, pp. 3243-3250, Sep 2009 [link]  DOI: 10.1039/B911412M [pdf]
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      This study presents a microfluidic system that incorporates electroosmotic pumps, a concentration gradient generator and a fish cell line (rainbow trout gill) to perform toxicity testing on fish cells seeded in the system. The system consists of three mechanical components: (1) a toxicity testing chip containing a microfluidic gradient generator which creates a linear concentration distribution of toxicant in a cell test chamber, (2) an electroosmotic (EO) pump chip that controls the flow rate and operation of the toxicity chip, and (3) indirect reservoirs that connect the two chips allowing for the toxicant solution to be pumped separately from the electroosmotic pump solution. The flow rate and stability of the EO pumps was measured and tested by monitoring the gradient generator using fluorescence microscopy. Furthermore, a lethality test was performed with this system setup using a rainbow trout gill cell line (RTgill-W1) as the test cells and sodium dodecyl sulfate as a model toxicant. A gradient of sodium dodecyl sulfate, from 0 to 50 µg mL−1, was applied for 1 hr to the attached cells, and the results were quantified using a Live/DeadTMcell assay. This work is a preliminary study on the application of EO pumps in a living cell assay, with the potential to use the pumps in portable water quality testing devices with RTgill-W1 cells as the biosensors.

    C. Elbuken, M. B. Khamesee and M. Yavuz. “Design and implementation of a micromanipulation system using a magnetically levitated microgripper,” IEEE Tran. Mechatronics, v. 14, no. 4, pp. 434-445, Aug 2009 [link]  DOI: 10.1109/TMECH.2009.2023648 [pdf]
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      Magnetic levitation of microrobots is presented as a new technology for micromanipulation tasks. The microrobots were fabricated based on microelectromechanical systems technology and weigh less than 1 g. The robots can be positioned in 3-D using magnetic field. It is shown that microrobots can be produced using commercially available magnets or electrodeposited magnetic films. A photothermal microgripper is integrated to the microrobots to perform micromanipulation operations. The microgrippers can be actuated remotely by laser focusing that makes the microrobot free of any wiring. This leads to increased motion range with more functionality in addition to dust-free motion and ability to work in closed environments. The 3-D motion capability of the microrobots is verified experimentally and it was demonstrated that the microgrippers can be operated in a vertical range of 4 mm and a horizonal range of 4 mm × 5 mm. Micromanipulation experiments such as pick-and-place, pushing, and pulling were demonstrated using objects with 100 µm and 1 mm diameter.

    C. Elbuken, N. Topaloglu, P. M. Nieva, M. Yavuz and J. P. Huissoon. “Modeling and analysis of a novel 2-DOF bidirectional electro-thermal microactuator,” Microsystem Technologies, v. 15, no. 5, pp. 713-722, May 2009 [link]  DOI:10.1117/12.776594 [pdf]
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      In this paper, a four hot-arm U-shape electro-thermal actuator that can achieve bidirectional motion in two axes is introduced. By selectively applying voltage to different pairs of its four arms, the device can provide actuation in four directions starting from its rest position. It is shown that independent in-plane and out-of-plane motions can be obtained by tailoring the geometrical parameters of the system. The lumped model of the microactuator was developed using electro-thermal and thermo-mechanical analyses and validated using finite element simulations. The device has been fabricated using PolyMUMPs and experimental results are in good agreement with the theoretical predictions. Total in-plane deflections of 4.8 μm (2.4 μm in either direction) and upward out-of-plane deflections of 8.2 μm were achieved at 8 V of input voltage. The large achievable deflections and the higher degree-of-freedom of the proposed device compared to its counterparts, foresee its use in diverse MEMS applications.

      C. Elbuken, L. Gui, C. L. Ren, M. Yavuz and M. B. Khamesee. “Design and analysis of a polymeric photo-thermal actuator,” Sens. Actuators A, v. 147, pp. 292-299, July 2008 [link]  DOI:10.1016/j.sna.2008.04.019 [pdf]
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      This paper presents the modeling, simulation and characterization of a photo-thermally actuated bent-beam microactuator. The microactuator consists of a single polymeric layer (SU-8) fabricated with conventional photolithography techniques. The principle of operation is based on the thermal expansion of the bent-beams that absorb the required heat by laser illumination. This provides an effective non-contact actuation mechanism by laser beam focusing. A theoretical model of the microactuator is derived and verified by finite element simulations and experiments. The experiments show that a bent-beam actuator with 800 μm long, 40 μm wide, 100 μm thick and 6° bent arms achieves a tip displacement of 16 μm with an incident laser beam of 50 mW power while keeping the maximum temperature less than 125 °C. This study merges the advantages of photo-thermal actuation with practicality of polymeric materials. To verify the effectiveness of the proposed microactuator mechanism, a microgripper with bent-beam actuator was fabricated and characterized. It has been demonstrated that the opening of the gripping fingers can be increased from 20 to 50 μm for a microgripper with 1000 μm long fingers with an incident laser power of 50 mW. This polymeric microgripper with photo-thermal actuation provides a way of gentle grasping with electrical isolation, high repeatability and low temperature operation that is particularly crucial for biomanipulation applications. The polymeric photo-thermal actuator described in this study expands the practical applications of microactuators/microgrippers which are critical tools in bioMEMS devices.

    C. Elbuken, M. Yavuz and M. B. Khamesee. “Development of crystalline magnetic thin films for microlevitation,” AIP J. of Applied Physics 104, 044905, Aug 2008  (selected for Sep 2008 issue of Virtual J. Nanoscale Science & Technology) [link] DOI: 10.1063/1.2969832 [pdf]
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      In recent years, magnetic levitation is finding interesting applications in various fields related to microdevices. Producing inexpensive microfabricated magnetic films is of high importance to all magnetically levitated microdevices. This paper introduces a microlevitation system and presents the fabrication of Co–Ni–Mn–P films using electrodeposition. The fabrication parameters are varied such that magnetization direction of the film is varied by changing the crystal structure. The magnetic properties of the films such as coercivity, remanence, and maximum energy product demonstrate that hexagonal structure promotes out-of-plane magnetization whereas cubic structure reinforces in-plane magnetization. The performance of the Co–Ni–Mn–P films is evaluated by magnetic levitation experiments of silicon samples. Satisfactory results are obtained toward the goal of realization of a magnetically levitated microgripper.

     C. Elbuken, E. Shameli and M. B. Khamesee. “Modeling and analysis of eddy current damping for high precision magnetic levitation of a small magnet,” IEEE Tran. on Magnetics, v. 43, no. 1, pp. 26-32, Jan 2007 [link]  DOI:10.1109/TMAG.2006.885859 [pdf]
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      This paper presents modeling and analysis of eddy-current damping that is formed by a conductive plate placed below the levitating object in order to suppress vibrations and ensure stability. It is demonstrated that vibrations should be damped to preserve stability and precision especially for stepwise motion. The levitated object is a small permanent magnet in our experiments. A magnetic drive unit is used for vertical motion of the magnet. Eddy-current distribution in the plate is calculated by solving diffusion equation for vector magnetic potential. The eddy force applied to the object is derived by a coil model representation. It is shown that if a 20 mm radius, 9 mm thick aluminum circular plate is used for eddy-current damping, the levitated object can closely follow a step input with a steadystate precision varying between 0.04 and 0.07 mm depending on the plate object distance. Eddy-current damping is a key technique that improves levitation performance to increase the diversity of applications of magnetic levitation systems in micromanipulation and microelectronic fabrication.

      C. Elbuken, M. B. Khamesee and M. Yavuz. “Eddy current damping for magnetic levitation: Downscaling from macro to micro levitation,” J. Phys. D: Appl. Phys., v. 39, pp 3932-3938, Sep 2006 [link] DOI:10.1088/0022-3727/39/18/002 [pdf]
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      Magnetic levitation of miniaturized objects is investigated in this paper. A magnetic levitation setup is built to implement one-dimensional magnetic levitation motion. It was observed that as the levitated object becomes smaller, magnetic levitation suffers more from undesired vibrations. As a solution, eddy current damping is offered and implemented successfully by placing conductive plates close to the levitated object. An analytical expression for damping coefficient is derived. Experimentally, it is shown that eddy current damping can reduce the RMS positioning error to the level of more than one third of its original value for a 0.386 g object levitated in an air-gap region of 290 mm. The proposed system has the potential to be used for micro-manipulation purposes in a high motion range of 39.8 mm.

  • Z. Isiksacan and C. Elbuken, “Microfluidic measurement of erythrocyte sedimentation rate and monitoring of erythrocyte aggregation,” 20th International Conf. on Miniaturized Systems, MicroTAS 2016, Dublin, Ireland, 9 – 13 October 2016.

    Z. Isiksacan and C. Elbuken, “Point-of-care measurement of erythrocyte sedimentation rate,” 3rd International Congress on Biosensors, Ankara, Turkey, 5 – 7 October 2016.

    A. Kalantarifard and C. Elbuken, “Highly monodispersed droplet generation using a microfluidic system,” 3rd International Congress on Biosensors, Ankara, Turkey, 5 – 7 October 2016.

    Z. Isiksacan and C. Elbuken, “Ultra fast microfluidic measurement of erythrocyte sedimentation rate,” Microfluidics 2016, EMBL Heidelberg, Germany, 24 – 26 July 2016.

    M. Serhatlioglu, B. Ortac, C. Elbuken, N. Biyikli and M.E. Solmaz, “CO2 polishing of femtosecond laser micromachined microfluidic channels,”CLEO: Science and Innovations 2016, 5-10 June 2016.

    Z. Isiksacan and C. Elbuken, “A point-of-care device for fast erythrocyte sedimentation rate measurement,” International Conference of Microfluidics, Nanofluidics and Lab-on-a-Chip, Dalian, China, 10-12 June 2016.

    Z. Isiksacan and C. Elbuken, “Development of an optomechanical point-of-care device for erythrocyte sedimentation rate measurement,” Biosensors 2016, Gothenburg, Sweden, 25-27 May, 2016.

    B. Garipcan, O. Oztürk,F. Z. Erkoc, M. Marcali, C. Elbuken and R. Rasier, “Development of artificial corneal endothelium microenvironment by biomimetic and bioinspired approaches,” Bio-inspired Materials 2016, Potsdam, Germany, 22 – 25 February 2016.

    M.T. Guler, I. Bilican, Z. Isiksacan, S. Agan, C. Elbuken, “An in situ fabrication technique to form integrated microelectrodes,” 19th International Conf. on Miniaturized Systems, MicroTAS 2015, Gyeongju, Korea, 25 – 29 October 2015.

    M. Marcali, C. Elbuken, “Automated detection of blood type inside microfluidic droplets”, 2nd International Congress on Biosensors ,Izmir, Turkey, 10-12 June 2015

    P. K. Isgor, C. Elbuken, “On-PCB droplet detection and sorting”, 2nd International Congress on Biosensors, Izmir, Turkey, 10-12 June 2015 (poster)

    Z. Isiksacan, M. T. Guler, B. Aydogdu, I. Bilican, C. Elbuken, “A novel rapid prototyping method for PDMS-based microfluidic platforms”,  2nd International Congress on Biosensors, Izmir, Turkey, 10-12 June 2015 (poster)

    M.T Guler, I. Bilican, M. Yuksel, S. Agan, C. Elbuken, “Electrical detection of single bacterium from drinking water”, 2nd International Congress on Biosensors ,Izmir, Turkey, 10-12 June 2015 (poster)

    I. Bilican, M.T Guler, M. Yuksel, S. Agan, C. Elbuken, “Electrical detection of red blood cells on a microfluidic device”, 2nd International Congress on Biosensors ,Izmir, Turkey, 10-12 June 2015 (poster)

    M.Marcali, C.Elbuken, “Impedimetric detection of agglutination reaction inside microfluidic droplets”, Microfluidics, Physics and Chemistry of Microscale Technology for Advancing and Translating Discovery, Mount Snow, VT, USA, 31 May-5 June 2015 (poster)

    I. Bilican, M.T. Guler, M. Yuksel, S. Agan, C. Elbuken, “Solvent sensing from capacitance based on interdigitated microelectrodes” OEMT 2015, 1st International Conferece on Organic Electronic Material Technologies, Elazig, Turkey, 25-28 March 2015

     M.T. Guler, I. Bilican, T. Tekinay, S. Agan, C. Elbuken, “Electrical detection of microbeads in dry medium” OEMT 2015, 1st International Conferece on Organic Electronic Material Technologies, Elazig, Turkey, 25-28 March 2015

    C. Elbuken, “A Microfluidic device for rapid determination of erythrocyte sedimentation rate”, Selectbio Conference on Lab-on-a-chip & Microfluidics, Berlin, Germany, 17-18 March 2015 (poster)

    I. Bilican, M.T. Guler, M. Yuksel, S. Agan, C. Elbuken, “Easy and cost effective fabrication method of 3D electrodes for impedance based detection” MIDEM, Society for Microelectronics, Electronic Components and Materials, Ljubljana, Slovenia, 6-10 October 2014

    I. Bilican, M.T. Guler, S. Agan, C. Elbuken, “Cost effective 3D electrodes for impedance based single particle detection,” EMBL Microfluidics 2014, Heidelberg, Germany, 23 June 2014  (poster)

    P.K. Isgor, M. Marcali, and C. Elbuken, “Capacitive microfluidic droplet content detection,” EMBL Microfluidics 2014, Heidelberg, Germany, 23 June 2014  (poster)

    O. Cakmak, N. Kilinc, E. Ermek, A. Mostafazadeh, C. Elbuken, G. G Yaralioglu and H. Urey. LoC sensor array platform for real-time coagulation measurements, IEEE 27th Conf. on MEMS, 330-333, San Francisco, CA, USA, Jan. 2014

    T. Glawdel, C. Elbuken, and C. Ren. Droplet Formation in Microfluidic T-junction Generators Operating in the Transitional Regime, APS Meeting, 34004, Baltimore, MD, USA, March 2013

    O. Cakmak, C. Elbuken, E. Ermek, S. Bulut, Y. Kilinc¸ I. Baris, H. Kavaklı, E. Alaca, H. Urey, “MEMS biosensor for blood plasma viscosity measurements” New Biotechnology vol 29 S, September 2012

    L. Lee, T. Glawdel, C. Elbuken, B. Sansom, N. Vo, and C. Ren. Fish and Chips Towards the Development of Portable Water Testing Devices, In Vitro Cellular & Developmental Biology – Animal, 46, S41-S42, 2010

    T. Glawdel, C. Elbuken, and C. L. Ren. Modeling of T-junction droplet generator in the transition regime, ASME 2010, Vancouver, Canada, Nov. 2010

    C. Elbuken, T. Glawdel, D. Chan and C. L. Ren. Real-time capacitive detection of microdroplets, ASME 2010, Vancouver, Canada, Nov. 2010

    S.M. Shameli, C. Elbuken, J. Ou, C. L. Ren, and J. Pawliszyn. Integration of a PDMS/SU-8/Quartz microfluidic chip with a novel macroporous poly dimethylsiloxane (PDMS) membrane for membrane isoelectric focusing of proteins using whole-channel imaging detection, ICNMM 2010, Montreal, Canada, Aug. 2010

    T. Glawdel, C. Elbuken, C. L. Ren. Modeling of T-junction generator operating in the transitional regime: defining the fitting parameters, 16th USNCTAM, University Park, PA USA, July 2010

    T. Glawdel, C. Elbuken, C. L. Ren and L. E. J. Lee. Electro-osmotic pumps with steady long-term performance for cytotoxicology studies, MicroTAS 2009, Jeju, Korea, Nov. 2009

    L.E. Lee, T. Glawdel, C. Elbuken, N. C. Bols and C. L. Ren. Development of microfluidic-based Lab-on-a-Chip devices with fish cell lines as biosensors for aquatic contaminants, Ann.l Main Meeting of the Society of Experimental Biology, Glasgow, UK, June 2009

    C. Elbuken M. B. Khamesee and M. Yavuz. Magnetic levitation as a micromanipulation technique for MEMS, IEEE ICMA 2009, Changchun, Jilin, China, Aug. 2009

    C. Elbuken, L. Gui, C. L. Ren, M. Yavuz and M. B. Khamesee. Design and characterization of a polymeric photo-thermal microgripper for micromanipulation, ASME 2008, Boston, MA, USA, Nov. 2008

    C. Elbuken, L. Gui, C. L. Ren, M. Yavuz and M. B. Khamesee. A Monolithic polymeric microgripper with photo-thermal actuation for biomanipulation, IEEE ICMA 2008, Takamatsu, Kagawa, Japan, August 2008

    N. Topaloglu, C. Elbuken, P. M. Nieva, M. Yavuz and J. P. Huissoon. Modeling and simulation of a 2-DOF bidirectional electrothermal microactuator, NDE’08, San Diego, USA. Proc. SPIE vol. 6926, 692605, Apr. 2008

    C. Elbuken, M. B. Khamesee and M. Yavuz. Large air-gap magnetic levitation of electrodeposited Co-Ni-Mn-P films, IEEE ICMA 2007, Harbin, China, Aug 2007, pp. 3272–3277

    C. Elbuken, M. Yavuz, M. B. Khamesee, S. Kambe and O. Ishii. Investigation of electrodeposited Co-based films used for magnetic levitation application, MST 2007, Detroit, Michiganm USA, Sep. 2007, pp. 195-205

    C. Elbuken, M. B. Khamesee and M. Yavuz. Magnetic levitation of Co-Ni-Mn-P coated silicon samples toward microlevitation, CANCAM’07, Toronto, Canada, June 2007

    C. Elbuken, M. Yavuz and M. B. Khamesee. Structural and mechanical properties of electrodeposited Co-Ni-Mn-P films, CANCAM’07, Toronto, Canada, June 2007

    C. Elbuken, M. B. Khamesee and M. Yavuz. Damping control in magnetic levitation of micro objects, IECON’06, Paris, France, Nov. 2006, pp. 4170-4175

    M. Yavuz, M. S. Boybay, C. Elbuken, M. J. Andrews, C. R. Hu and J.H. Ross. Bi-Sr-Ca-Cu-O superconducting thin films: theory and experiment, EUCAS’05, Vienna, Austria, Conference Series 43, July 2006, pp. 277-280
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  • US20160091509A1, Cartridge device with segmented fluidics for assaying coagulation in fluid samples , Katrina Petronilla Di Tullio, Jay Kendall Taylor, John Lewis Emerson Campbell, Caglar Elbuken, Shelia Diane Ball, Noam Saul Lightstone

     PCT/EP2012/070947A method and an apparatus for the detection of a tagging material in fluids, Hakan Urey, Havva Yagci Acar, Caglar Elbuken, Basarbatu Can, Osman Vedat Akgun, Fahri Kerem Uygurmen

    T. Glawdel, C. Elbuken and  C. L. Ren, “ Droplet Generation in Microfluidics,”  Encyclopedia of Microfluidics and Nanofluidics,  2012 [link]. DOI 10.1007/978-3-642-27758-0_1713-1

     

     

  • New Scientist Magazine, “Getting rid of wobbles at tiny scales” issue 2569, pg 30, 2006

    The Economist, “Look, no wires” Science & Technology“, April 2009

    The Records, “Tiny flying robots to learn surgery”

    CNN Turk, “Manyetik alanda kontrollü uçabilen robot” April 2009 (in Turkish)