45 results found
Kassanos P, 2021, Bioimpedance Sensors: A Tutorial, IEEE SENSORS JOURNAL, Vol: 21, Pages: 22190-22219, ISSN: 1530-437X
Moreddu R, Mahmoodi N, Kassanos P, et al., 2021, Stretchable nanostructures as optomechanical strain sensors for ophthalmic applications, ACS APPLIED POLYMER MATERIALS, Vol: 3, Pages: 5416-5424, ISSN: 2637-6105
The intraocular pressure (IOP) is a physiological parameter that plays a crucial role in preventing, diagnosing, and treating ocular diseases. For example, lowering the IOP is the primary focus of glaucoma management. However, IOP is a widely varying parameter, and one-off measurements are prompt to errors. Developing portable solutions for continuous monitoring the IOP is a critical goal in ophthalmology. Here, stretchable nanostructures were developed as strain-tunable diffraction gratings and integrated into a contact lens. They exhibited a limit of detection (LOD) <2 mmHg and a linear response in the range of interest (15–35 mmHg). Nanopatterns were characterized under monochromatic laser sources and further integrated into a soft contact lens. A smartphone readout method based on preferentially reflected colors was proposed to pave the way toward smartphone-based ocular health monitoring.
Moreddu R, Nasrollahi V, Kassanos P, et al., 2021, Lab-on-a-contact lens platforms fabricated by multi-axis femtosecond laser ablation, Small, Vol: 17, ISSN: 1613-6810
Contact lens sensing platforms have drawn interest in the last decade for the possibility of providing a sterile, fully integrated ocular screening technology. However, designing scalable and rapid contact lens processing methods while keeping a high resolution is still an unsolved challenge. In this article, femtosecond laser writing is employed as a rapid and precise procedure to engrave microfluidic networks into commercial contact lenses. Functional microfluidic components such as flow valves, resistors, multi-inlet geometries, and splitters are produced using a bespoke seven-axis femtosecond laser system, yielding a resolution of 80 µm. The ablation process and the tear flow within microfluidic structures is evaluated both experimentally and computationally using finite element modeling. Flow velocity drops of the 8.3%, 20.8%, and 29% were observed in valves with enlargements of the 100%, 200%, and 300%, respectively. Resistors yielded flow rate drops of 20.8%, 33%, and 50% in the small, medium, and large configurations, respectively. Two applications were introduced, namely a tear volume sensor and a tear uric acid sensor (sensitivity 16 mg L−1), which are both painless alternatives to current methods and provide reduced contamination risks of tear samples.
Kassanos P, Seichepine F, Yang G-Z, 2021, A Comparison of Front-End Amplifiers for Tetrapolar Bioimpedance Measurements, IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT, Vol: 70, ISSN: 0018-9456
Keshavarz M, Chowdhury AKMRH, Kassanos P, et al., 2020, Self-assembled N-doped Q-dot carbon nanostructures as a SERS-active biosensor with selective therapeutic functionality, Sensors and Actuators B: Chemical, Vol: 323, Pages: 128703-128703, ISSN: 0925-4005
Kassanos P, 2020, Analog-digital computing let robots go through the motions, SCIENCE ROBOTICS, Vol: 5, ISSN: 2470-9476
Keshavarz M, Wales DJ, Seichepine F, et al., 2020, Induced neural stem cell differentiation on a drawn fiber scaffold-toward peripheral nerve regeneration, Biomedical Materials, Vol: 15, ISSN: 1748-6041
To achieve regeneration of long sections of damaged nerves, restoration methods such as direct suturing or autologous grafting can be inefficient. Solutions involving biohybrid implants, where neural stem cells are grown in vitro on an active support before implantation, have attracted attention. Using such an approach, combined with recent advancements in microfabrication technology, the chemical and physical environment of cells can be tailored in order to control their behaviors. Herein, a neural stem cell polycarbonate fiber scaffold, fabricated by 3D printing and thermal drawing, is presented. The combined effect of surface microstructure and chemical functionalization using poly-ʟ-ornithine (PLO) and double-walled carbon nanotubes (DWCNTs) on the biocompatibility of the scaffold, induced differentiation of the neural stem cells (NSCs) and channeling of the neural cells was investigated. Upon treatment of the fiber scaffold with a suspension of DWCNTs in PLO (0.039 gL-1) and without recombinants a high degree of differentiation of NSCs into neuronal cells was confirmed by using nestin, galactocerebroside (GalC) and doublecortin (Dcx) immunoassays. These findings illuminate the potential use of this biohybrid approach for the realization of future nerve regenerative implants.
Kassanos P, Berthelot M, Kim JA, et al., 2020, Smart sensing for surgery from tethered devices to wearables and implantables, IEEE Systems Man and Cybernetics Magazine, Vol: 6, Pages: 39-48, ISSN: 2333-942X
Recent developments in wearable electronics have fueled research into new materials, sensors, and microelectronic technologies for the realization of devices that have increased functionality and performance. This is further enhanced by advances in fabr ication methods and printing techniques, stimulating research on implantables and the advancement of existing medical devices. This article provides an overview of new designs, embodiments, fabrication methods, instrumentation, and informatics as well as the challenges in developing and deploying such devices and clinical applications that can benefit from them. The need for and use of these technologies across the perioperative surgical-care pathway are highlighted, along with a vision for the future and how these tools can be adopted by potential end users and health-care systems.
Kassanos P, Seichepine F, Kassanos I, et al., 2020, Development and Characterization of a PCB-Based Microfluidic YChannel*, 2020 42nd Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) in conjunction with the 43rd Annual Conference of the Canadian Medical and Biological Engineering Society, Publisher: IEEE
Ranque P, George C, Dubey RK, et al., 2020, Scalable Route to Electroactive and Light Active Perylene Diimide Dye Polymer Binder for Lithium-Ion Batteries, ACS APPLIED ENERGY MATERIALS, Vol: 3, Pages: 2271-2277, ISSN: 2574-0962
Keshavarz M, Kassanos P, Tan B, et al., 2020, Metal-oxide surface-enhanced Raman biosensor template towards point-of-care EGFR detection and cancer diagnostics, NANOSCALE HORIZONS, Vol: 5, Pages: 294-307, ISSN: 2055-6756
Kassanos P, Rosa BG, Keshavarz M, et al., 2020, From wearables to implantables-clinical drive and technical challenges, Wearable Sensors: Fundamentals, Implementation and Applications, Pages: 29-84, ISBN: 9780128192467
With an increasingly aging population and a need for decentralization of health care and remote, at-home, and bedside monitoring, there is a growing necessity for wearables and implantables with advanced capabilities that provide data suitable for clinical diagnostics. In this chapter, musculoskeletal applications serve as the exemplar for these technologies. The clinical drives for sensing and augmented therapy are highlighted for conditions including bone fractures, nonunions, ligament tears, stroke, and arthritis. Piezoresistive strain sensors based on elastomeric composites, hydrogels, liquid-metals, and magnetoelastic sensors are discussed, together with electrophysiological recordings to monitor mechanical loading and muscle activity coupled with discussions on bioimpedance, motion sensors, hydrogels, regenerative methods, and electrical stimulation. Passive approaches based on resonant systems with sensing capabilities are highlighted as an approach for implantables. The necessity for biocompatibility and appropriate packaging, as well as the potential for biodegradability, are also emphasized.
Sunny AI, Rahman M, Koutsoupidou M, et al., 2019, Feasibility Experiments to Detect Skin Hydration Using a Bio-Impedance Sensor, 2019 41ST ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY (EMBC), Pages: 6032-6035, ISSN: 1557-170X
Kassanos P, Seichepine F, Wales D, et al., 2019, Towards a Flexible/Stretchable Multiparametric Sensing Device for Surgical and Wearable Applications, IEEE Biomedical Circuits and Systems Conference (BioCAS), Publisher: IEEE, ISSN: 2163-4025
Kassanos P, Seichepine F, Keshavarz M, et al., 2019, Towards a Flexible Wrist-Worn Thermotherapy and Thermoregulation Device, 19th Annual IEEE International Conference on Bioinformatics and Bioengineering (BIBE), Publisher: IEEE, Pages: 644-648, ISSN: 2471-7819
Kassanos P, Seichepine F, Yang G-Z, 2019, Characterization and Modeling of a Flexible Tetrapolar Bioimpedance Sensor and Measurements of Intestinal Tissues, 19th Annual IEEE International Conference on Bioinformatics and Bioengineering (BIBE), Publisher: IEEE, Pages: 686-690, ISSN: 2471-7819
Kassanos P, Anastasova S, Yang G-Z, 2018, Towards Low-Cost Cell Culturing Platforms with Integrated Sensing Capabilities, IEEE Biomedical Circuits and Systems Conference (BioCAS) - Advanced Systems for Enhancing Human Health, Publisher: IEEE, Pages: 327-330, ISSN: 2163-4025
Kassanos P, Anastasova S, Yang G-Z, 2018, A Low-Cost Amperometric Glucose Sensor Based on PCB Technology, 17th IEEE SENSORS Conference, Publisher: IEEE, Pages: 1031-1034, ISSN: 1930-0395
Anastasova S, Kassanos P, Yang G-Z, 2018, Electrochemical Sensor Designs for Biomedical Implants, Implantable Sensors and Systems: From Theory to Practice, Editors: Yang, Publisher: Springer, Pages: 19-98, ISBN: 978-3-319-69748-2
The need to record directly the sensing target of interest in the vicinity of where a physiological and clinically relevant event takes place, rather than indirectly or through surrogate measures, has led to the need for implantable monitoring devices. In addition to ensuring the sensitivity and specificity of sensor responses, issues related to sensor fouling, drift, biocompatibility, and hermeticity of the packaging are important considerations. This chapter examines the current state of the art of sensing techniques, focusing on electrochemical methods (potentiometry, amperometry, and voltammetry), due to their simplicity in design and fabrication , as well as low-power operation.
Kassanos P, Ip H, 2018, Ultra-Low Power Application-Specific Integrated Circuits for Sensing, Implantable Sensors and Systems: From Theory to Practice, Editors: Yang, Publisher: Springer, Pages: 281-437, ISBN: 978-3-319-69748-2
In the quest for ever-reducing system size and increased integration and functionality, application-specific integrated circuit (ASIC) technology plays a pivotal role in modern implants, where custom circuits designed at transistor and device levels are replacing off-the-shelf commercial chips and bulky benchtop systems. Recently, commercial system-on-chip (SoC) devices encompassing digital microcontrollers, radio, and analog–digital converters, as well as reconfigurable amplifier circuits, are widely available. Despite this, further development of ASIC-specific implantable systems is required, particularly in the area of multi-channel array sensor interfaces, ultra-low power data acquisition, and circuits that work with specialized micro-sensors for implants. ASICs designed to focus on a particular application have given designers the freedom to optimize power consumption for a set task, unlike general-purpose SoCs that have to cater for a wide range of applications and hence typically consume more power. In this chapter, we begin with a survey on the latest development of ASICs and related integrated systems from literature. This is followed by an overview of technological trends in integrated circuit/sensor fabrication and fusion. The rest of the chapter focuses on a number of engineering aspects related to ultra-low power ASIC circuits appropriate for implantable sensors and sensor front-ends, covering bioimpedance, neural and electrochemical sensor measurement circuits, as well as low-power analog-to-digital converter design and architectures.
Kassanos P, Anastasova S, Yang G-Z, 2018, Sensor Embodiment and Flexible Electronics, Implantable Sensors and Systems: From Theory to Practice, Editors: Yang, Publisher: Springer, Pages: 197-279, ISBN: 978-3-319-69748-2
Sensor embodiment and packaging are particularly important for implantable systems. One key element is the development of flexible electronics. Traditional electronics, based on rigid silicon technologies, is associated with a number of intrinsic disadvantages. The inherent brittleness of inorganic semiconductors and stiffness of Si wafer-based devices represent a major issue when interfaced with tissues. This is because our internal organs are complex and they have innate responses to reject foreign bodies. Furthermore, tissues are soft, and they undergo constant motion and deformation. In this chapter, we will discuss current progress in flexible printed circuit board (FPC/FPCB) technologies and provide a review of new fabrication techniques and materials for making soft devices and interconnects suitable for implantable applications. Issues related to geometrical designs for mechanically resilient flexible devices, hermetic packaging, biocompatibility and encapsulation are addressed.
Kassanos P, Anastasova S, Yang G-Z, 2018, Electrical and Physical Sensors for Biomedical Implants, Implantable Sensors and Systems: From Theory to Practice, Editors: Yang, Publisher: Springer, Pages: 99-195, ISBN: 978-3-319-69748-2
In addition to the electrochemical sensors discussed in Chap. 2, a range of other sensing modalities are also important for biomedical and implantable applications. The frequency-dependent electrical properties of tissues are essential for assessing various physiological parameters. This, for example, can be quantified via electrical bioimpedance measurements, which can be combined and corroborated with electrochemical sensors. The human body is a dynamic system in constant motion; therefore, sensors for the measurement of physical properties such as strain and pressure are also important. Sensors for these applications rely on the measurement of resistance, capacitance, and sometimes inductance, and these will also be discussed in this chapter for completeness. Temperature is an important health marker for various applications, and consequently the current state of the art in temperature sensors is also discussed, in terms of both monolithic integration and discrete sensor solutions. Monitoring of the electrical response of the nervous system and the delivery of stimuli represent an important family of applications for neuroscience research and neuroprosthetic devices. These will be addressed in this chapter, along with various application scenarios. Other aspects to be discussed include sensor metrics, such as sensitivity, limit of detection, stability, linear range, selectivity, and specificity.
Kassanos P, Yang G-Z, 2017, A CMOS Programmable Phase Shifter for Compensating Synchronous Detection Bioimpedance Systems, 24th IEEE International Conference on Electronics, Circuits and Systems (ICECS), Publisher: IEEE, Pages: 218-221
Electrical bioimpedance is used in a wide variety of biomedical applications. A common circuit topology for extracting tissue impedance from voltage measurements following excitation with an ac current, is synchronous detection (SD), which requires both quadrature (Q) and in phase (I) signals. These are often obtained by a quadrature oscillator, which also drives a voltage controlled current source (VCCS). At high frequencies the VCCS introduces phase delays to the output current, leading to frequency dependent errors in the calculated impedance, as the injected current will no longer be in phase or in quadrature with I and Q. In this paper, a novel low power programmable CMOS phase shifter is presented, which is driven by two quadrature sine waves to produce an output signal between 0° and 90°. The proposed technique is implemented with linearized transconductors operating in weak inversion for linear transconductance programmability. In contrast to other solutions, the phase delay is not a function of the power supply or a capacitor, and thus it is not affected by changes in the power supply and is more chip area efficient. Preliminary simulation results demonstrating the operation of the topology are presented with a 0.18 pm TSMC technology.
Anastasova-Ivanova S, Kassanos P, Yang G-Z, 2017, Multi-Parametric Rigid and Flexible, Low-Cost, Disposable Sensing Platforms for Biomedical Applications, Biosensors and Bioelectronics, Vol: 102, Pages: 668-675, ISSN: 0956-5663
The measurement of Na+, K+ and H+ is essential in medicine and plays an important role in the assessment of tissue ischemia. Microfabrication, inkjet- and screen-printing can be used for solid contact ion selective electrodes (ISE) realization; these, however, can be non-standardized, costly and time consuming processes. We present the realization of ISEs on post-processed electrodes fabricated via standardized printed circuit board (PCB) manufacturing techniques. In vitro results are presented from two rigid platforms (32 ISEs) for liquid sample dip-stick measurements and two flexible platforms (6 and 32 ISEs) for post-surgical intestinal tissue monitoring, each with a common reference electrode (RE). These are combined with optimized tetrapolar bioimpedance sensors for tissue ischemia detection. Both electroless and hard gold PCB finishes are examined. Apart from the electroless rigid platform, the rest demonstrated comparable and superior performance, with the pH sensors demonstrating the greatest deviation; the flexible hard gold platform achieved a sensitivity 4.6 mV/pH and 49.2 mV/pH greater than the electroless flexible and rigid platforms, respectively. The best overall performance was achieved with the hard gold flexible platform with sensitivities as large as 73.4 mV/pH, 56.3 mV/log [Na+], and 57.4 mV/log [K+] vs. custom REs on the same substrate. Simultaneous measurements of target analytes is demonstrated with test solutions and saliva samples. The results exhibit superior performance to other PCB-based pH sensors, demonstration of Na+ and K+ PCB-based sensors with comparable performance to potentiometric sensors fabricated with other techniques, paving the way towards mass-produced, low-cost, disposable, multi-parametric chemical sensing diagnostic platforms.
Kassanos P, Ip HMD, Yang G-Z, 2015, A Tetrapolar Bio-Impedance Sensing System for Gastrointestinal Tract Monitoring, IEEE 12th International Conference on Wearable and Implantable Body Sensor Networks (BSN), Publisher: IEEE
Kassanos P, Triantis IF, 2014, A CMOS Multi-Sine Signal Generator for Multi-Frequency Bioimpedance Measurements, International Symposium on Circuits and Systems, ISCAS, Publisher: IEEE
Kassanos P, Constantinou L, Triantis IF, et al., 2014, An Integrated Analog Readout for Multi-Frequency Bioimpedance Measurements, IEEE Sensors Journal
Bioimpedance spectroscopy is used in a wide range of biomedical applications. This paper presents an integrated analog readout, which employs synchronous detection to perform galvanostatic multi-channel, multi-frequency bioimpedancemeasurements. The circuit was fabricated in a 0.35-μm CMOS technology, occupying an area of 1.52 mm2. The effect of random dc offsets is investigated, along with the use of chopping to minimize them. Impedance measurements of a known RC load and skin (using commercially available electrodes) demonstratethe operation of the system over a frequency range up to 1 MHz. The circuit operates from a ±2.5 V power supply and has a power consumption of 3.4-mW per channel.
Kassanos P, Triantis IF, 2014, A low-complexity CMOS multi-frequency signal generator for impedimetric applications, 24thWorld Congress on Biosensors
Kassanos P, Triantis IF, Demosthenous A, 2013, A CMOS Magnitude/Phase Measurement Chip for Impedance Spectroscopy, IEEE SENSORS JOURNAL, Vol: 13, Pages: 2229-2236, ISSN: 1530-437X
Kassanos P, Triantis IF, Demosthenous A, 2011, A novel front-end for impedance spectroscopy, Sensors, 2011 IEEE, Publisher: IEEE, Pages: 327-330, ISSN: 1930-0395
A novel method for calculating unknown impedances is presented. In contrast to synchronous detection (SD), which provides the real and imaginary components, the magnitude and phase of the impedance are calculated. Non-accurate generation of the required in-phase and quadrature signals required in SD and mismatches between the channels generate large errors. The proposed method does not require such signals. The measured potential across the sensor is rectified and then low-pass filtered to obtain the magnitude. The phase is calculated by two comparators followed by an XOR gate. A prototype of the system was built using discrete components and proof of concept measurements were carried out using resistors and capacitors of known values.
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