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  • Conference paper
    Kalofonou M, Toumazou C, 2014,

    An ISFET based analogue ratiometric method for DNA methylation detection

    , IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 1832-1835, ISSN: 0271-4302

    This paper presents the concept of a ratiometric approach for DNA methylation detection using the “Methylation Cell” for the indication of epigenetic abnormalities related to cancer. The “Methylation Cell” allows real-time detection of pH signals resulting from DNA based reactions using ISFET sensors, performing continuous computation of the ratio of DNA methylation, giving a discrete output signal when DNA methylation exceeds a certain predefined percentage. Fabricated in a typical 0.35μm CMOS process, it uses current-mode translinear circuits to perform computation in low power. Experimental results are presented, demonstrating its capabilities through an integration in a Lab-on-Chip (LoC) set-up using a microfluidic assembly.
  • Journal article
    Trantidou T, Rao C, Barrett H, Camelliti P, Pinto K, Yacoub MH, Athanasiou T, Toumazou C, Terracciano CM, Prodromakis Tet al., 2014,

    Selective hydrophilic modification of Parylene C films: a new approach to cell micro-patterning for synthetic biology applications

    , Biofabrication, Vol: 6, ISSN: 1758-5090

    We demonstrate a simple, accurate and versatile method to manipulate Parylene C, a material widely known for its high biocompatibility, and transform it to a substrate that can effectively control the cellular microenvironment and consequently affect the morphology and function of the cells in vitro. The Parylene C scaffolds are fabricated by selectively increasing the material's surface water affinity through lithography and oxygen plasma treatment, providing free bonds for attachment of hydrophilic biomolecules. The micro-engineered constructs were tested as culture scaffolds for rat ventricular fibroblasts and neonatal myocytes (NRVM), toward modeling the unique anisotropic architecture of native cardiac tissue. The scaffolds induced the patterning of extracellular matrix compounds and therefore of the cells, which demonstrated substantial alignment compared to typical unstructured cultures. Ca2+ cycling properties of the NRVM measured at rates of stimulation 0.5–2 Hz were significantly modified with a shorter time to peak and time to 90% decay, and a larger fluorescence amplitude (p < 0.001). The proposed technique is compatible with standard cell culturing protocols and exhibits long-term pattern durability. Moreover, it allows the integration of monitoring modalities into the micro-engineered substrates for a comprehensive interrogation of physiological parameters.
  • Journal article
    Leene LB, Constandinou TG, 2014,

    Ultra-low power design strategy for two-stage amplifier topologies

    , Electronics Letters, Vol: 50, Pages: 583-585, ISSN: 0013-5194

    A novel two-stage amplifier topology and ultra-low power design strategy for two-stage amplifiers that utilises pole zero cancellation to address the additional power requirements for stability are presented. For a 288 nA total bias, the presented amplifier achieves a 1.07 MHz unity gain frequency with a 8560 pF MHz/mA figure of merit.
  • Journal article
    Lang Z, Gurrala R, Kaye S, Toumazou C, Cooke Get al., 2014,

    POC diagnostic test for HLA B<SUP>☆</SUP>5701 using pH-based label-free detection

    , HIV MEDICINE, Vol: 15, Pages: 71-71, ISSN: 1464-2662
  • Journal article
    Pagkalos I, Herrero P, Toumazou C, Georgiou Pet al., 2014,

    Bio-Inspired Glucose Control in Diabetes Based on an Analogue Implementation of a β-Cell Model

    , IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS, Vol: 8, Pages: 186-195, ISSN: 1932-4545
  • Journal article
    Toumazou C, Thay TSLK, Georgiou P, 2014,

    A new era of semiconductor genetics using ion-sensitive field-effect transistors: the gene-sensitive integrated cell

    , PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES, Vol: 372, ISSN: 1364-503X
  • Journal article
    Luan S, Constandinou TG, 2014,

    A Charge-Metering Method for Voltage-Mode Neural Stimulation

    , Journal of Neuroscience Methods, Vol: 224, Pages: 39-47, ISSN: 0165-0270

    Electrical Neural Stimulation is the technique used to modulate neural activity by inducing an instantaneous charge imbalance. This is typically achieved by injecting a constant current and controlling the stimulation time. However, constant voltage stimulation is found to be more energy-efficient although it is challenging to control the amount of charge delivered. This paper presents a novel, fully-integrated circuit for facilitating charge-metering in constant voltage stimulation. It utilises two complementary stimulation paths. Each path includes a small capacitor, a comparator and a counter. They form a mixed-signal integrator that integrates the stimulation current onto the capacitor whilst monitoring its voltage against a threshold using the comparator. The pulses from the comparator are used to increment the counter and reset the capacitor. Therefore, by knowing the value of the capacitor, threshold voltage and output of the counter, the quantity of charge delivered can be calculated. The system has been fabricated in 0.18μm CMOS technology, occupying a total active area of 339μm×110μm. Experimental results were taken using: (1) a resistor-capacitor EEI model and (2) platinum electrodes with ringer solution. The viability of this method in recruiting action potentials has been demonstrated using a cuff electrode with Xenopus Sciatic nerve. For a 10nC target charge delivery, the results of (2) show a charge delivery error of 3.4% and a typical residual charge of 77.19pC without passive charge recycling. The total power consumption is 45μW. The performance is comparable with other publications. Therefore, the proposed stimulation method can be used as a new approach for neural stimulation.
  • Conference paper
    Herrero P, Liu C, Georgiou P, Oliver N, El Sharkawy A, Pesl P, Reddy M, Johnston D, Toumazou Cet al., 2014,

    HYPOGLYCEMIA PREDICTION BASED ON EXTENDED KALMAN FILTER USING A PHYSIOLOGICAL MODEL OF GLUCOSE REGULATION

    , Publisher: MARY ANN LIEBERT, INC, Pages: A82-A83, ISSN: 1520-9156
  • Conference paper
    Reddy M, Oliver N, Herrero P, Georgiou P, El Sharkawy M, Pesl P, Jugnee N, Thomson H, Toumazou C, Johnston Det al., 2014,

    GLYCAEMIC VARIABILITY AND QUALITY OF LIFE IN SUBJECTS WITH TYPE 1 DIABETES MELLITUS - IS THERE A CORRELATION?

    , Publisher: MARY ANN LIEBERT, INC, Pages: A59-A59, ISSN: 1520-9156
  • Conference paper
    Reddy M, Oliver N, Herrero P, Georgiou P, Misra S, El Sharkawy M, Pesl P, Jugnee N, Toumazou C, Johnston Det al., 2014,

    THE IMPACT OF INSULIN INFUSION RATE VARIABILITY ON GLYCAEMIC VARIABILITY IN ADULTS WITH TYPE 1 DIABETES

    , Publisher: MARY ANN LIEBERT, INC, Pages: A59-A59, ISSN: 1520-9156
  • Journal article
    Barsakcioglu D, Liu Y, Bhunjun P, Navajas J, Eftekhar A, Jackson A, Quian Quiroga R, Constandinou TGet al., 2014,

    An Analogue Front-End Model for Developing Neural Spike Sorting Systems

    , IEEE Transactions on Biomedical Circuits and Systems, Vol: 8, Pages: 216-227
  • Conference paper
    Guven O, Eftekhar A, Hoshyar R, Frattini G, Kindt W, Constandinou TGet al., 2014,

    Realtime ECG Baseline Removal: An Isoelectric Point Estimation Approach

    , IEEE Biomedical Circuits and Systems (BioCAS) Conference, Pages: 29-32

    This paper presents a novel method for ECG baseline drift removal while preserving the integrity of the ST segment. Baseline estimation is achieved by tracking 3 isoelectric points within the ECG waveform as fiducial markers used in an interpolation filter. These points are determined relative to the QRS complex, which is extracted using a known method (Pan-Tompkins algorithm). The proposed algorithm has been tested extensively using synthetic signals and also validated with real data. The synthetic signals assume a 2mV p-p ECG signal and 300uV p-p baseline drift in the presence of noise artefacts including EMG pickup (20 dB – max. 200uV), and residual power-line interference (50uV p-p). The results show a maximum (worst-case ST-segment distortion) error of 34.7uV (mean), 27.8uV (median) and 21.2uV (std. dev.) across 50 randomly generated synthetic ECG signals each containing 100 heartbeats. Validation of the algorithm applied to signals from the MIT-BIH arrhythmia databases reveals maximum error per P-T intervalwith mean, median and std. dev. of 34.4uV, 35.2uV and 9.6uV respectively with suppressed motion artefacts.
  • Conference paper
    Yang Y, Boling S, Eftekhar A, Paraskevopoulou SE, Constandinou TG, Mason AJet al., 2014,

    Computationally efficient feature denoising filter and selection of optimal features for noise insensitive spike sorting

    , IEEE Annual Meeting of the Engineering in Biology and Medicine Society (EMBC), Publisher: IEEE
  • Conference paper
    Trantidou T, Tariq M, Pinto K, Toumazou C, Terracciano C, Prodromakis Tet al., 2014,

    A lab-on-chip approach for monitoring the electrochemical activity of biorealistic cell cultures

    , IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 642-645, ISSN: 0271-4302
  • Conference paper
    Sohbati M, Toumazou C, 2014,

    A Temperature Insensitive Continuous Time Δ<i>pH</i> to Digital Converter

    , IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 37-40, ISSN: 0271-4302
  • Conference paper
    Herrero P, El Sharkawy M, Pesl P, Reddy M, Oliver N, Johnston D, Toumazou C, Georgiou Pet al., 2014,

    Live Demonstration: A Handheld Bio-inspired Artificial Pancreas for Treatment of Diabetes

    , IEEE Biomedical Circuits and Systems Conference (BioCAS), Publisher: IEEE, Pages: 172-172, ISSN: 2163-4025
  • Conference paper
    Pesl P, Herrero P, Reddy M, Oliver N, Johnston D, Toumazou C, Georgiou Pet al., 2014,

    Live Demonstration: An Advanced Bolus Calculator for Diabetes Management - A Clinical and Patient Platform

    , IEEE Biomedical Circuits and Systems Conference (BioCAS), Publisher: IEEE, Pages: 175-175, ISSN: 2163-4025
  • Journal article
    Navajas J, Barsakcioglu D, Eftekhar A, Jackson A, Constandinou TG, Quian Quiroga Ret al., 2014,

    Minimum Requirements for Accurate and Efficient Real-Time On-Chip Spike Sorting

    , Journal of Neuroscience Methods, Pages: 51-64
  • Book chapter
    Shepherd LM, Constandinou TG, Toumazou C, 2014,

    Towards ultra-low power bio-inspired processing

    , Body Sensor Networks, Publisher: Springer London, Pages: 273-299, ISBN: 9781447163732

    The natural world is analogue and yet the modern microelectronic world with which we interact represents real world data using discrete quantities manipulated by logic. In the human space, we are entering a new wave of body-worn biosensor technology for medical diagnostics and therapy. This new trend is beginning to see the processing interface move back to using continuous quantities, which are more or less in line with the biological processes. We label this computational paradigm “bio-inspired” because of the ability of silicon chip technology which enables the use of inherent device physics, allowing us to approach the computational efficiencies of biology. From a conceptual viewpoint, this has led to a number of more specific morphologies including neuromorphic and retinomorphic processing. These have led scientists to model biological systems such as the cochlea and retina and gain not only superior computational resource efficiency (to conventional hearing aid or camera technology), but also an increased understanding of biological and neurological processes.
  • Conference paper
    Zheng L, Leene L, Liu Y, Constandinou TGet al., 2014,

    An Adaptive 16/64 kHz, 9-bit SAR ADC with Peak-Aligned Sampling for Neural Spike Recording

    , IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 2385-2388

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