Karan Kaler

Karan Kaler
The University of Calgary | HBI · Department of Electrical and Computer Engineering

About

130
Publications
10,943
Reads
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2,112
Citations
Citations since 2016
7 Research Items
608 Citations
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2016201720182019202020212022020406080100
2016201720182019202020212022020406080100
2016201720182019202020212022020406080100
Introduction
Skills and Expertise

Publications

Publications (130)
Article
Full-text available
Nucleic acid based diagnostic techniques are routinely used for the detection of infectious agents. Most of these assays rely on nucleic acid extraction platforms for the extraction and purification of nucleic acids and a separate real-time PCR platform for quantitative nucleic acid amplification tests (NATs). Several microfluidic lab on chip (LOC)...
Article
Full-text available
Nanocrystalline Tin Oxide (SnO 2) is Non-Stoichiometric in Nature with Functional Properties Suitable for gas sensing. In this study, SnO 2 nanoparticles were prepared by the sol–gel technique, which were then characterised using X-ray diffraction. The nanoparticles showed tetragonal structure with an average crystallite size of 18 nm. The stretchi...
Article
Full-text available
Quantitative, reverse transcription, polymerase chain reaction (qRT-PCR) is facilitated by leveraging droplet microfluidic (DMF) system, which due to its precision dispensing and sample handling capabilities at microliter and lower volumes has emerged as a popular method for miniaturization of the PCR platform. This work substantially improves and...
Article
Full-text available
In this investigation, various metal oxide (ZrO2, MgO, TiO2) nanoparticles were prepared using the hot-air spray pyrolysis method. The prepared nanoparticles were characterized using the X-ray diffraction (XRD) technique, scanning electron microscopy (SEM), and transmission electron microscopy. The colloidal silica (SiO2) sol was prepared using the...
Article
Full-text available
Droplet microfluidics (DMF) is a fluidic handling technology that enables precision control over dispensing and subsequent manipulation of droplets in the volume range of microliters to picoliters, on a micro-fabricated device. There are several different droplet actuation methods, all of which can generate external stimuli, to either actively or p...
Article
Full-text available
In this work, nano-sized spherical MnO2 particles with large surface area were synthesized employing spray pyrolysis for application in a Zn/MnO2 primary cell. Furthermore, we experimentally investigated the performance of nano-sized MnO2 particles when mixed with conductive additives, such as graphite and Vulcan carbon. The effect of particle size...
Article
Miniaturized bio-diagnostic devices have the potential to allow for rapid pathogen screening in clinical patient samples, as a low cost and portable alternative to conventional bench-top equipment. Miniaturization of key bio-diagnostic techniques, such as: nucleic acid detection and quantification, polymerase chain reaction (PCR), DNA fingerprintin...
Article
Lipid bilayer membranes in biological cells are an essential component of cellular infrastructure and furthermore responsible for various transductional afunctionalities. Synthetic lipid membranes can be deposited as supported lipid bilayer (SLB) on functionalized solid surfaces or, as large bilayer lipid vesicles (BLV). Such artificial lipid membr...
Article
Nano-textured super hydrophobic (SH) surfaces can achieve very high droplet contact angles (typically >150°) and are furthermore associated with reduced surface adsorption of enzymes and other macro-molecules. The advantages of such SH surfaces have already been explored for electrostatic based digital microfluidic (DMF) devices where the high CA a...
Article
Dielectrophoresis (DEP) is one of the principle electrokinetic methods of handling and processing micro-sized dielectric particles and biological cells immersed in aqueous media. Example applications include the utility of DEP to affect separation of cells based on polarization, cell trapping/concentration, cell aggregation, etc. More recently the...
Article
One of the key structural features of a surface microfluidic (SMF) device is the surface coating, since it directly affects both the performance and reliability of the SMF device. This work examines and compares the performance of liquid dielectrophoresis (LDEP) SMF devices, fabricated with conventional spin-coated Teflon® surface to those coated w...
Article
Chip based pathogen detection is one of the prime motivation for research in the field of microfluidics. Thus far, on-chip detection has primarily been demonstrated using closed-channel microfluidic devices, which are prone to certain limitations in terms of detection threshold and complexity of sample handling. Present day pathogen detection metho...
Article
Full-text available
Giant unilamellar vesicles (GUVs) [1], typically >10 μm in diameter, can serve as interesting models for mimicking biological membranes and furthermore can be usefully leveraged in drug delivery and bio-sensor applications. In this paper, we have demonstrated a chip based vesicle dispensing scheme that utilizes liquid dielectrophoresis (L-DEP) to d...
Article
Full-text available
Lipid bilayer vesicles when assembled with specific bio-probes or markers can serve as bio-sensors with potential utility in micro-biotechnology, serving as tailored bio-sensors, drug-delivery agents and mimicking cellular behavior. We report on a Surface Microfluidic (SMF) chip based vesicle dispensing scheme to rapidly dispense variable sized lar...
Article
Droplet based microfluidic systems, in recent years, have demonstrated numerous advantages and exciting potential for Lab-On-a Chip applications. In order to fully realize the potential benefits of this technology, one requires precision dispensing and manipulation of droplets of known volume and sample concentration, in a rapid and controlled mann...
Article
Full-text available
Liquid dielectrophoresis (L-DEP), when deployed at microscopic scales on top of hydrophobic surfaces, offers novel ways of rapid and automated manipulation of very small amounts of polar aqueous samples for microfluidic applications and development of laboratory-on-a-chip devices. In this article we highlight some of the more recent developments an...
Article
We predict the complex polarizability of a realistic model of a red blood cell (RBC), with an inhomogeneous dispersive and anisotropic membrane. In this model, the frequency-dependent complex electrical parameters of the individual cell layers are described by the Debye equation while the dielectric anisotropy of the cell membrane is taken into acc...
Article
To circumvent the complexity of the detection systems of microfluidic devices, Hartley et al. recently reported on a CMOS optical active pixel sensor (APS) for near-field detection and counting of microscopic particles. To further enhance the digital cytometric capabilities of the original sensor, we modified and utilized a dual APS-array scheme to...
Conference Paper
Quantitative analysis of chemical and biochemical molecules is an important requirement in many biochemical assays and can be a challenging task in microfluidic systems due to the smaller sample volumes. In the present study, we report on the detection and quantification of nucleic acid samples contained in nanoliter (nL) and picoliter (pL) droplet...
Article
Full-text available
Vesicles, also known as liposome, are bilayers of lipid molecules enclosing a fluidic media. Vesicles can be formed by spontaneous assembling of phospholipid bilayer separating two different solvent media. Alternatively, vesicles can be formed as solid supported membranes. Such vesicles have potential in understanding the structural and other prope...
Article
Liquid Dielectrophoresis (L-DEP) has been successfully leveraged at microscopic scales and shown to provide a controllable means of on-chip precision dispensing and manipulation of sub-nanoliter single emulsion droplets. In this paper, we report on the dynamics of a DEP actuated emulsion jet prior to break-up and compare its characteristic behavior...
Article
Surface microfluidic systems have emerged as an attractive alternative to conventional closed-channel microfluidic devices. In many such systems, electric fields are leveraged for the manipulation and transport of discrete nanoliter droplets on open planar surfaces. The present research work discusses dielectrophoretic liquid and droplet actuations...
Conference Paper
A Dielectrophoresis (DEP) based Surface Microfluidic (SMF) device has been successfully configured to facilitate multiplexed DNA hybridization assay. In this paper, we have demonstrated the utility of a 2×2 multiplexed DEP based droplet dispensing and conveyance schemes to manipulate sub-nanoliter DNA sample droplets and facilitate high throughput...
Article
Dielectrophoresis based liquid and droplet actuations have been successfully leveraged at microscale to dispense multiple arrays of sample and reagent droplets and furthmore mix them in all possible binary combinations. We demonstrate a multiplexed (2X2 matrix) surface microfluidic device that could dispense multiple droplets of 4 different samples...
Conference Paper
A hybrid integrated CMOS/Microfluidic system has been developed for cytometric applications. The active area of the CMOS sensor consists of two linear arrays of Active Pixel Sensor (APS). Near-field coupling of the CMOS sensor to the microfluidic system is achieved using a flip chip solder-reflow technique. The experimental results show that the sy...
Conference Paper
We report on the development of a feedback control system that utilizes a custom CMOS optical sensor, to facilitate controlled and precise dispensing and transport of nano-liter liquid sample droplets by leveraging liquid-DEP (L-DEP) and droplet-DEP (D-DEP) actuation schemes. Operationally, L-DEP and D-DEP typically require application of AC voltag...
Article
A miniaturized microfluidic device was developed to facilitate electromanipulation of bacterial respiratory pathogens. The device comprises a microchip with circular aluminum electrodes patterned on glass, which is housed in a microfluidic system fabricated utilizing polydimethylsiloxane. The device provides sample preparation capability by exploit...
Article
Miniaturized fluidic systems have been developed in recent years and offer new and novel means of leveraging the domain of microfluidics for the development of micro-total analysis systems (microTAS). Initially, such systems employed closed microchannels in order to facilitate chip-based biochemical assays, requiring very small quantities of sample...
Article
Integrated PCR–CE chip technology has immense potential to be applied in clinical diagnostics. In this work we demonstrate the application of our integrated PCR–CE chip for the detection of the respiratory pathogen Bordetella pertussis. A series of experiments with varying cell concentrations (200,000–2cfu) were performed to obtain the analytical d...
Article
Twenty-four-hour ambulatory pH monitoring is an essential tool for diagnosing gastroesophageal reflux disease (GERD). Simultaneous impedance and pH monitoring of the esophagus improves the detection and characterization of GERD. Conventional catheter-based monitoring systems are uncomfortable and interfere with the normal activity of the patient. T...
Article
A reconfigurable microfluidic chip system is described which facilitates multiple electrode contacts to a PDMS micro-fluidic chip. The PDMS micro-channels are reversibly bonded on to the chip, and are readily removed for cleaning, changing analytes or to allow different micro-fluidic channel or electrode geometries to be used. Up to 60 independent...
Article
We investigated the adsorption of Taq enzyme, using sessile droplets, on different microfluidic materials. In propagating adsorption materials, the contact angle (CA) of a sessile Taq droplet continually recedes and collapses due to adsorption. Contrastingly, in contained adsorption materials it exhibits an initial reduced CA due to an instantaneou...
Article
Analysis of chemical and biological samples requires one or more of the following sequential steps: sampling, sample transport, sample pretreatment and sample processing. As a result of miniaturization, such total analysis systems offer manifold advantages such as mass production, portability and hence on-site operation, ease of use, low sample con...
Article
Full-text available
We present a prototype microfluidic device developed for the continuous dielectrophoretic (DEP) fractionation and purification of sample suspensions of biological cells. The device integrates three fully functional and distinct units consisting of an injector, a fractionation region, and two outlets. In the sheath and sample injection ports, the ce...
Article
Reported are motivations and approaches for the integration of custom sensors with microfluidic devices for cytometry on a chip and related fluid metering applications. To demonstrate, details of a digital 16-element mixed-signal CMOS active pixel optical sensor with adaptive spatial filtering is first described. The 0.18-mum CMOS fabricated sensor...
Article
An integrated microfluidic system for combined manipulation, pre-concentration, and lysis of samples containing Bordetella pertussis by dielectrophoresis and electroporation has been developed and implemented. The microfluidic device was able to pre-concentrate the amount of B. pertussis cells present in 200 microl of a B. pertussis suspension stoc...
Article
Clinical diagnostics and genomic research often require performing numerous genetic tests. While microfluidic devices provide a low-cost alternative to such demands, integrated microfluidic devices are fabricated using expensive technology not always affordable for single use. However, carryover cross-contamination (CXC) concerns (i.e. either false...
Article
In clinical applications and life science research, genetic analysis based on PCR amplification of DNA fragments and subsequent CE detection, has become an indispensable technique. An integrated microfluidic PCR and CE chip offer an attractive alternative to conventional laboratory DNA processing due to reduced reagent consumption, increased device...
Conference Paper
The ability to manipulate volumes of liquid and their constituent components, such as cells, organelles and their nucleic acids, utilizing very small (microliter) sample volumes provides new and novel opportunities and capabilities in microchip based bio-analysis and detection or lab-on-a-chip based diagnostics. The low sample volume requirements a...
Patent
Full-text available
A swallowable electronic bolus or "pill" that can monitor any one or more of the following parameters in real time as the bolus moves through the esophagus: (i) acceleration of the bolus; (ii) velocity of the bolus; (iii) position of the bolus; and (iv) contractile force on the bolus that pushes it through the gastrointestinal tract.
Article
Esophageal motility disorders are diagnosed by monitoring pressure, pH, and bolus transit in the lumen of the organ. However, an integrated multichannel esophageal catheter capable of monitoring all these phenomena in a single clinical test is still lacking. The present work proposes innovative techniques and methods to develop a multichannel integ...
Article
A miniaturized system for sample preparation of relevant bacterial pathogens has been developed using a variety of microfabrication techniques. The system manipulates and disrupts Eschericha coli bacterial cells using dielectrophoresis, electroporation and enzymes. The microchip consisted of circular gold electrodes patterned on glass using standar...
Article
Full-text available
This paper presents a novel current-mode instrumentation amplifier (CMIA) that utilizes an operational floating current conveyor (OFCC) as a basic building block. The OFCC, as a current-mode device, shows flexible properties with respect to other current- or voltage-mode circuits. The advantages of the proposed CMIA are threefold. First, it offers...
Patent
Full-text available
The lack of Safe, reliable, automated and clinically accept able blood Sampling has been the main problem precluding the development of real-time Systems for blood analysis and Subsequent closed-loop physiological function control. While the analysis of a static blood sample in laboratory conditions has been rapidly advancing in reliability and blo...
Conference Paper
In this paper, we present a new architecture for dielectrophoresis (DEP) analysis with programmable planar arrays of micro-electrodes called Lexel™. This software configurable architecture is able to implement a variety of AC electrokinetic techniques. The architecture is developed as a flexible IP (intellectual property) block and in conjunction w...
Article
Two possible system integration approaches for portable real time cytometry in microfluidic applications are discussed. An ocular mounted linear CMOS image sensor configured for real time detection of particles being transported in microfluidic channels is first described. This system delivers cytometry functionality utilizing standard microfluidic...
Conference Paper
This study presents the design, implementation, and testing of microelectromechanical system (MEMS)-based actuators. The concepts of electrostatic and thermal microactuation are discussed. Geometrically identical fixed-fixed microbeams were fabricated to compare quantitatively the two different actuation principles. The beams are implemented with M...
Conference Paper
Biomedical optical impedance sensors involve image processing of light blobs to extract information regarding a process such as pressure. These sensors utilize a light source to illuminate an imager chip. The edges of the light blob, its diameter and location are parameters of interest to characterize pressure dynamics. CMOS technology allows the c...
Conference Paper
Full-text available
In this article we report on a planar miniaturized dielectrophoretic (DEP) microfluidic device developed for the purpose of continuous fractionation and purification of sample suspensions of microscopic particles or biological cells, employing specially shaped nonuniform (isomotive) electric fields. The device integrates three fully functional and...
Conference Paper
Full-text available
Dielectrophoresis (DEP) has been successfully applied and demonstrated to provide novel and non-invasive means for characterizing, manipulating, trapping, separating and isolating microscopic sized particles, including biological cells. In this article, we report on the design, fabrication and performance of a novel, low cost, integrated Poly(dimet...
Conference Paper
Monitoring bolus transit in the esophagus has been pivotal for the diagnosis of achalasia, diffuse spasm, motor abnormalities associated with systemic disorders, and gastro-esophageal reflux disease. Despite recent advances in X-ray imaging and the introduction of multichannel intraluminal impedancometry, these studies remain moderately invasive. B...
Article
Full-text available
In this study we present an innovative design idea for a semi-invasive blood sampling, analysis and drug delivery device called “Electronic Mosquito” (“e-Mosquito”). The major building blocks of the device are discussed. The principle of operation is described and its feasibility is demonstrated. The integration of the microsystem is outlined and i...
Conference Paper
This paper presents the development and experimental verification of the lexel (electric field element) array, a programmable two-dimensional array of discrete, independent microelectrodes that constructs arbitrary electric field shapes to manipulate microscopic particles and cells. The lexel array forms the base structure of a future low-power bio...
Conference Paper
Integrated, automated microfluidic chips offer fast, inexpensive and sensitive detection of molecular characteristics of cancer, e.g. diagnostic/monitoring tests that include RT-PCR, capillary electrophoresis, and/or fluorescent staining. Devices that include sample processing capability require minute amounts of tissue. Analysis of molecular signa...
Conference Paper
Pressure, pH and bolus transit measurements are commonly used for diagnosing esophageal motility disorders. In the present study, a probe that integrates novel techniques for monitoring all variables of interest for esophageal testing is proposed. Innovative catheter design offers proper selection of frequencies and electrode arrangement for enhanc...
Conference Paper
Full-text available
Dielectrophoresis (DEP), traveling wave dielectrophoresis (TWD) and electrorotation (ROT) are established electro-kinetic methods that can be usefully applied for the selective and controlled manipulation, isolation, concentration, separation and characterization of electrically polarizable particles, such as intact cells. Using a custom integrated...
Article
The study of the dielectric properties of micrometer- or nanometer-scale particles is of particular interest in present-day applications of biomedical engineering. Electrokinetics utilises electrically energised microelectrode structures within microfluidic chambers to noninvasively probe the physiological structure of live cancer cells. A system i...
Conference Paper
We present a method to assess microchip performance for on-chip electrophoretic separations. The assessment is realized through electrophoretic manipulation of a DNA size standard using specially designed electric voltage programs. Results achieved from the assessment could be used as an indicator of microchip "aging" in terms of lowered resolution...
Article
This work integrates rapid techniques for mutation detection by producing single-stranded DNA and (renatured) double-stranded DNA on-chip, labeling these with fluorescent DNA stains and then performing two complementary methods of mutation detection-single stranded conformation polymorphism (SSCP) analysis and heteroduplex analysis (HA). This invol...
Article
This paper presents the development and experimental verification of a DEP fluidic system capable of fractionation of intact biological cells in suspension into purer subpopulations. This was accomplished by employing a specially shaped nonuniform electric field, synthesized by microfabricated planar microelectrode arrays, housed on an insulating g...
Article
At present there is an enormous discrepancy between our nanotechnological capabilities (particularly our nanobiotechnologies), our social wisdom, and consensus on how to apply them. To date, cost considerations have greatly constrained our application of nanotechnologies. However, novel advances in microsystem platform technologies are about to gre...
Article
Full-text available
Electromanipulation of microparticles utilizing microelectrodes has demonstrated considerable promise for the characterization, separation and handling of biological cells. Presently considerable research and development effort is directed towards the development of miniaturized fluidic systems with integrated dielectrophoresis (DEP) electrodes. Th...
Conference Paper
In the past, a variety of complementary techniques such as dielectrophoretic levitation, electrorotation and travelling wave dielectrophoresis (TWD) have each been individually and effectively applied in demonstrating the promising applications of DEP in the life and biological science. In this regard, however, little effort has been devoted to the...