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203
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Introduction
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November 2008 - present
Publications
Publications (203)
Prostate cancer (PCa) is the second most common cancer among men and the fifth leading cause of cancer death. Circulating tumor cell (CTC) enumeration and characterisation in PCa has been shown to provide valuable information on prognosis of disease, therapy management and detection of resistance. Here, Cellsway’s microfluidic platform for high-thr...
In recent years, single cell isolation and analysis have become crucial, driven by the need to study rare cells in cell biology research, diagnostics, and personalized medicine. However, existing platforms for isolating small cell numbers are expensive, labor-intensive, and not widely accessible. To address this, we present a low-cost, repeatable m...
Realizations of fully implantable cochlear implants (FICIs) for providing adequate solution to esthetic concerns and frequent battery replacement have lacked of addressing system level criteria as a complete device. Here, we present a full-custom FICI that considers design of both an implantable sensor for wide range sound sensing and a signal cond...
The growing interest in microfluidic biosensors has led to improvements in the analytical performance of various sensing mechanisms. Although various sensors can be integrated with microfluidics, electrochemical ones have been most commonly employed due to their ease of miniaturization, integration ability, and low cost, making them an established...
This paper presents an acoustic transducer for fully implantable cochlear implants (FICIs), which can be implanted on the hearing chain to detect and filter the ambient sound in eight frequency bands between 250 and 6000 Hz. The transducer dimensions are conventional surgery compatible. The structure is formed with 3 × 3 × 0.36 mm active space for...
The isolation of circulating tumor cells (CTCs) from peripheral blood with high efficiency remains a challenge hindering the utilization of CTC enrichment methods in clinical practice. Here, we propose a microfluidic channel design for the size-based hydrodynamic enrichment of CTCs from blood in an epitope-independent and high-throughput manner. Th...
Microfluidics enables the integration of whole protocols performed in a laboratory, including sample loading, reaction, extraction, and measurement steps on a single system, which offers significant advantages thanks to small-scale operation combined with precise fluid control. These include providing efficient transportation mechanisms and immobil...
Platinum (Pt) is widely used in MEMS applications due to its inert nature and high temperature stability. In general, Pt is patterned using dry etching methods which require expensive machinery. In this study, we propose wet etching of Pt electrodes of piezoelectric transducers in hot Aqua Regia at 60 °C using a thick photoresist as a masking mater...
Circulating tumor cells (CTCs) present in the bloodstream are strongly linked to the invasive behavior of cancer; therefore, their detection holds great significance for monitoring disease progression. Currently available CTC isolation tools are often based on tumor-specific antigen or cell size approaches. However, these techniques are limited due...
This paper presents a multi-channel acoustic transducer that works within the audible frequency range (250-5500 Hz) and mimics the operation of the cochlea by filtering incoming sound. The transducer is composed of eight thin film piezoelectric cantilever beams with different resonance frequencies. The transducer is well suited to be implanted in m...
This article presents an area efficient fully autonomous piezoelectric energy harvesting system to scavenge energy from periodic vibrations. Extraction rectifier utilized in the system is based on synchronized switch harvesting on inductor (SSHI) technique which enables system to outperform standard passive rectifiers. Compared to conventional SSHI...
We report the development of a lab-on-a-chip system, that facilitates coupled dielectrophoretic detection (DEP-D) and impedimetric counting (IM-C), for investigating drug resistance in K562 and CCRF-CEM leukemia cells without (immuno) labeling. Two IM-C units were placed upstream and downstream of the DEP-D unit for enumeration, respectively, befor...
Low powered fully implantable cochlear implants (FICIs) untangle the aesthetic concerns and battery replacement problems of conventional cochlear implants. However, the reported FICIs lack proper charge balancing and require multiple external supplies to operate. In this work, a complete low power FICI interface circuit is designed that operates wi...
This paper presents a low-profile and autonomous piezoelectric energy harvesting system consisting of an extraction rectifier and a maximum power point tracking (MPPT) circuit for powering portable electronics. Synchronized switch harvesting on capacitor-inductor (SSHCI) technique with its unique two-step voltage flipping process is utilized to dow...
In this work, a wide input/output range triple mode rectifier circuit operating at 13.56 MHz is implemented to power up medical implants. The proposed novel multi-mode rectifier circuit charges the load for an extended coupling range and eliminates the requirement of alignment magnets. The charging process is achieved in three different modes based...
BioMEMS, the biological and biomedical applications of micro-electro-mechanical systems (MEMS), has attracted considerable attention in recent years and has found widespread applications in disease detection, advanced diagnosis, therapy, drug delivery, implantable devices, and tissue engineering. One of the most essential and leading goals of the B...
Being one of the major pillars of liquid biopsy, isolation and characterization of circulating tumor cells (CTCs) during cancer management provides critical information on the evolution of cancer and has great potential to increase the success of therapies. In this article, we define a novel strategy to effectively enrich CTCs from whole blood base...
In this study, we investigated the performance of 2D simulations to predict the droplet sizes under varying flow conditions. Simple 2D models are lacking in presenting correct results because the top and bottom wall boundaries are excluded despite their significant effect on the flow construction. Here, we added an extra drag term representing
the...
We investigated the cell focusing performance of a CEA type microchannel, which comprises several throttles connecting circular wells in a zigzag arrangement. By obtaining the spatial distribution of the lift force using direct numerical simulations (DNS), we revealed the expected particle trajectories for CEA microchannel by sampling the
circular...
Microbial Fuel Cells (MFCs) are biological fuel cells based on the oxidation of fuels by electrogenic bacteria to generate an electric current in electrochemical cells. There are several methods that can be employed to improve their performance. In this study, the effects of gold surface modification with different thiol molecules were investigated...
This paper presents an analytical model to estimate the actuation potential of an electrostatic parylene-C diaphragm, processed on a glass wafer using standard microelectromechanical systems (MEMS) process technology, and integrable to polydimethylsiloxane (PDMS) based lab-on-a-chip systems to construct a normally-closed microvalve for flow manipul...
The detection of circulating tumor cells (CTCs) in blood is crucial to assess metastatic progression and to guide therapy. Dielectrophoresis (DEP) is a powerful cell surface marker‐free method that allows intrinsic dielectric properties of suspended cells to be exploited for CTC enrichment/isolation from blood. Design of a successful DEP‐based CTC...
This paper presents a self-powered interface circuit to rectify and manage the AC output of the piezoelectric energy harvesters (PEH) by utilizing Self-Investing Synchronous Electric Charge Extraction technique (SI-SECE). The system invests charges from the battery
to PEH to improve the electromechanical coupling factor and consequently the energy...
This paper presents a multi-channel piezoelectric acoustic transducer that is working within the audible frequency band (250- 5500 Hz). The transducer consists of eight cantilevers with thin film PLD-PZT piezoelectric layers. The transducer is well suited to be implanted in middle ear cavity with an active volume of 5×5×0.6 mm 3 and mass of 4.8 mg...
This paper presents an ultra-low power current-mode circuit for a bionic ear interface. Piezoelectric (PZT) sensors at the system input transduce sound vibrations into multi-channel electrical signals, which are then processed by the proposed circuit to stimulate the auditory nerves consistently with the input amplitude level. The sensor outputs ar...
This paper presents a self-adapting synchronized-switch harvesting (SA-SSH) interface circuit to extract energy from vibration-based piezoelectric energy harvesters (PEHs). The implemented circuit utilizes a novel switching technique to recycle optimum amount of harvested charge on piezoelectric capacitance to strengthen the damping-force, and simu...
This paper presents an ultralow power interface circuit for a fully implantable cochlear implant (FICI) system that stimulates the auditory nerves inside cochlea. The input sound is detected with a multifrequency piezoelectric (PZT) sensor array, is signal-processed through a front-end circuit module, and is delivered to the nerves through current...
This paper presents a novel self-powered and fully
autonomous interface circuit to extract piezoelectric energy from
vibrations available in the environment for supplying DC voltage
to electronic loads. A new energy extraction technique called
Synchronized Switch Harvesting on Capacitor-Inductor (SSHCI)
is utilized, which reduces system cost throug...
This study aimed to measure and compare the cytoplasmic ion concentrations of the parental cells and their drug resistant progenies. High-level laboratory and clinically-relevant multidrug resistance (MDR) cell line models were developed and investigated for K562 and CCRF-CEM cells, respectively. Measurements were achieved using a modified version...
This paper presents an efficient hybrid energy harvesting interface to synergistically scavenge power from electromagnetic (EM) and piezoelectric (PE) sources, and drive a single load. The EM harvester output is rectified through a self-powered active doubler structure, and stored on a storage capacitor. The stored energy is then transferred to the...
This paper presents a method for realizing energy neutral operation on energy harvesting wireless sensor nodes (WSN) and its implementation, regarding that the available environmental energy is unpredictable and changes over time. The method utilizes adaptive duty cycling which provides energy-neutral operation according to the energy available in...
This paper reports the development of a single cantilever thin film PLD-PZT transducer prototype. The device was experimentally characterized by attaching it on an acoustically vibrating membrane resembling the behavior of the eardrum. Acceleration characteristic of the sensor attached on the membrane was obtained by using a Laser Doppler Vibromete...
This paper presents a self-powered interface circuit to extract energy from ambient vibrations for powering up microelectronic devices. The circuit interfaces a piezoelectric energy harvesting MEMS device to scavenge acoustic energy. Synchronous electric charge extraction (SECE) technique is deployed through the implementation of a novel multi-stag...
Isolation and characterization of circulating tumor cells (CTCs) have important clinical significance in terms of prognosis and early detection of response to treatment. Moreover, downstream characterization of CTCs may help better patient stratification and therapy guidance. However, CTCs are extremely rare (~10 CTCs/1010 peripheral blood cells) a...
This paper presents an optimization study for a miniature electromagnetic energy harvester, by incorporating a non-magnetic inertial mass (tungsten) along with the axially oriented moving magnets. The aim is to decrease the operation frequency and increase the output power of the harvester with the usage of higher density material and larger magnet...
Methods for isolation and quantification of circulating tumor cells (CTCs) are attracting more attention every day, as the data for their unprecedented clinical utility continue to grow. However, the challenge is that CTCs are extremely rare (as low as 1 in a billion of blood cells) and a highly sensitive and specific technology is required to isol...
This paper presents a novel read-out approach both for eliminating parasitic feedthrough current and for enhancing the quality-factor (Q) of the resonating system at the same time. A new resonance characterization method based on sensing second harmonic component of the resonators was developed. Utilizing this method, the feedthrough current was el...
This paper presents an LOC system combining microfluidic DEP channel with a CMOS image sensor for label and lens free detection and real-time counting of MCF-7 cells under continuous flow. Trapped and then released MCF-7 cells are accurately detected and counted under flow with a CMOS image sensor integrated underneath the DEP channel, for the firs...
In this study, a MEMS-based microfluidic device combining DEP-based cell manipulation with size-based filtration for the enrichment of CTCs from blood with high-throughput was developed. Positive-DEP (pDEP) force and the hydrodynamic force have been used to fine-tune the cell movement over the planar electrodes (sliding) at a high flow rate (30 μl/...
Micro-Electro-Mechanical Systems (MEMS) has been an emerging field since early 1960s. In the last years, there have been number of MEMS based industrial applications from automotive to smart phones (gyroscopes, accelerometers, etc.). Utilizing MEMS in biomedical applications leads a promising research area, BioMEMS. BioMEMS enables miniaturization...
The number of circulating tumor cells (CTCs) in blood is associated with prognosis in several types of cancer. Isolation and characterization of CTCs have important clinical significance in terms of prognosis and early detection of response to treatment. Moreover, downstream characterization of CTCs may help better patient stratification and therap...
This study presents a triple hybrid energy harvesting system that combines harvested power from thermoelectric (TE), vibration-based electromagnetic (EM) and piezoelectric (PZT) harvesters into a single DC supply. A power management circuit is designed and implemented in 180 nm standard CMOS technology based on the distinct requirements of each har...
This paper presents design and fabrication of a MEMS-based thin film piezoelectric transducer to be placed on an eardrum for fully-implantable cochlear implant (FICI) applications. Resonating at a specific frequency within the hearing band, the transducer senses eardrum vibration and generates the required voltage output for the stimulating circuit...
This paper presents the first acoustic experimental results of a MEMS based bulk piezoelectric transducer for use in fully implantable cochlear implants (FICI). For this purpose, the transducer was attached onto an acoustically vibrating membrane. Sensing and energy harvesting performances were measured using neural stimulation and rectifier circui...
This paper presents the investigation of two different capacitive feedthrough current elimination methods with an analysis of the effect of the capacitive feedthrough current on the resonance characteristics of electrostatically actuated and sensed resonant MEMS sensors. Electrostatically actuated and sensed resonators have various applications, su...
This paper presents a compact model for threshold self-compensated rectifiers that can be used to optimize circuit parameters early in the design phase instead of time-consuming transient simulations. A design procedure is presented for finding the optimum aspect ratio of transistors used in the converter and number of rectifying stages to achieve...
In this study, a fabrication method utilizing parylene bonding for gravimetric resonant based mass sensors is presented. First, parylene bonding was experimentally tested and compared with the literature. Average shear strength was measured as 16.3 MPa (σ=3MPa). Then, resonators located on top of a microchannel for real-time detection were fabricat...
This letter presents a threshold-compensated UHF rectifier with a local self-calibrator in a 0.18-μm CMOS process. The self-calibrator compensates the intrinsic-Vth voltage for a broad range of input power intensity to decrease the sensitivity of the rectifier's power conversion efficiency (PCE) to the input power fluctuations. This makes the struc...
This paper presents a self-powered interface enabling battery-like operation with a regulated 3 V output from ac signals as low as 0.4 Vpeak, generated by electromagnetic energy harvesters under low frequency vibrations. As the first stage of the 180 nm standard CMOS circuit, harvested signal is rectified through an ac/dc doubler with active diodes...
This study presents a novel triple hybrid system that combines simultaneously generated power from thermoelectric (TE), vibration-based electromagnetic (EM) and piezoelectric (PZT) harvesters for a relatively high power supply capability. In the proposed solution each harvesting source utilizes a distinct power management circuit that generates a D...
This paper reports the design, fabrication, and testing of a microliter scale Microbial Fuel Cell (μMFC) based on silicon MEMS fabrication technology. μMFC systems are operated under different loads or open circuit to compare the effect of different acclimatization conditions on start-up time. Shewanella oneidensis MR-1 is preferred to be the bioca...
This paper presents a battery-less wireless sensor network (WSN) equipped with electromagnetic (EM) energy harvesters and sensor nodes with adjustable time-interval based on stored the energy. A wearable EM energy harvesting system is developed and optimized to power-up a typical wireless sensor mote from body motion. This is realized through chara...
This paper presents a novel biosensor structure consisting of a resonator placed at the top wall of a microchannel (Resonator-on-Microchannel: RoM). The proposed biosensor structure is aimed to be used for real-time gravimetric detection of microscale biological targets in liquid environment by tracking the resonance frequency change of the system...
This paper presents a new time-efficient modelling approach for UHF Dickson rectifiers. Due to the very low computation time, the approach can provide a quick and effective alternative to the standard transient simulations. The presented approach results in better estimation of the generated DC voltage and power conversion efficiency compared with...
This paper presents an optimization study to decrease the operation frequency and increase the output power of a miniature electromagnetic (EM) energy harvester, by incorporating a non-magnetic inertial mass together with the moving magnet. The harvester coil position has been optimized through FEM, and validated through tests. Experimental studies...
This study presents a novel hybrid system that combines the power generated simultaneously by a vibration-based Electromagnetic (EM) harvester and a UHF band RF harvester. The novel hybrid scavenger interface uses a power management circuit in 180 nm CMOS technology to step-up and to regulate the combined output. At the first stage of the system, t...