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• Journal article
  Dassau E, Hennings T, Fazio J, Atlas E, Phillip Met al., 2013,

  Closing the Loop

  , DIABETES TECHNOLOGY & THERAPEUTICS, Vol: 15, Pages: S29-S39, ISSN: 1520-9156
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• Journal article
  Salaoru I, Prodromakis T, Khiat A, Toumazou Cet al., 2013,

  Resistive switching of oxygen enhanced TiO₂ thin-film devices

  , APPLIED PHYSICS LETTERS, Vol: 102, ISSN: 0003-6951
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  • Citations: 50
• Journal article
  Premanode B, Toumazou C, 2013,

  Improving prediction of exchange rates using Differential EMD

  , EXPERT SYSTEMS WITH APPLICATIONS, Vol: 40, Pages: 377-384, ISSN: 0957-4174
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  • Citations: 51
• Conference paper
  Sohbati M, Georgiou P, Toumazou C, 2013,

  A Piecewise Linear Approximating ISFET Readout

  , IEEE Biomedical Circuits and Systems Conference (BioCAS), Publisher: IEEE, Pages: 37-40, ISSN: 2163-4025
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  • Citations: 3
• Conference paper
  Berdan R, Prodromakis T, Khiat A, Salaoru I, Toumazou C, Perez-Diaz F, Vasilaki Eet al., 2013,

  Temporal Processing with Volatile Memristors

  , IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 425-428, ISSN: 0271-4302
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  • Citations: 4
• Conference paper
  Sohbati M, Georgiou P, Toumazou C, 2013,

  REFET Replication for ISFET-based SNP Detection Arrays

  , IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 185-188, ISSN: 0271-4302
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  • Citations: 6
• Conference paper
  Trantidou T, Tariq M, Chang Y-C, Toumazou C, Prodromakis Tet al., 2013,

  Free-standing Parylene C Thin Films As Flexible pH Sensing Membranes

  , 12th IEEE Sensors Conference, Publisher: IEEE, Pages: 1827-1830, ISSN: 1930-0395
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• Conference paper
  Herrero P, Georgiou P, Oliver N, Reddy M, El Sharkawy M, Pesl P, Johnston D, Toumazou Cet al., 2013,

  In-Silico Comparison of a Bio-Inspired Glucose Controller vs. a PID controller with Insulin Feedback

  , Advanced Technologies & Treatments for Diabetes (ATTD)

  A recently developed bio-inspired glucose controller (BIAP) based on a model of β-cell physiology is compared against a recently published PID controller with insulin feedback (PID-IF) using the UVa/Padova T1DM metabolic simulator.Both controllers were tuned using a 24-hour scenario containing a 40g(10am) carbohydrates meal and initial blood glucose of 160mg/dl. A single tuning parameter was adjusted to stabilize glucose around 100mg/dl, avoiding dropping below 80mg/dl. To compare controllers, a 24-hour scenario containing 3 meals (30g(6am), 40g(2pm), 20g(10pm)) was employed. In both controllers, a partial bolus corresponding to 50% of the required insulin to cover a meal was delivered at the time of ingestion. Standard metrics provided by the simulator were employed for comparison purposes.See table for results of BIAP and PID-IF in n=10 adult, n=10 adolescent and n=10 children in-silico subjects. Mean blood glucose with PID-IF was lower than with BIAP in the adult cohort, percentage of time below target with BIAP was lower in the children cohort, percentage of time within target with BIAP was higher in the adolescents cohort and risk index was lower with BIAP in the adult and adolescent groups.The tuning parameter in BIAP correlated very well with the insulin sensitivity factor of the test subjects (R2=0.9), while the correlation observed within PID-IF was lower (R2=0.6).The BIAP glucose controller performed comparably to the PID-IF controller in in-silico setting with superior metrics in an adolescent cohort. The BIAP controller can be easily tuned by using a simple correlation with the insulin sensitivity factor.

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• Journal article
  Trantidou T, Prodromakis T, Tsiligkiridis V, Chang YC, Toumazou Cet al., 2013,

  Sensing H+ with conventional neural probes

  , Applied Physics Letters, Vol: 102, ISSN: 1077-3118

  In this paper, we demonstrate a technique for transforming commercially available neural probes used for electrical recordings, into chemical sensing devices for detection of ionic concentrations in electrolytes, with particular emphasis to pH. This transformation requires a single post-processing step to incorporate a thin indium tin oxide membrane for sensing H+. Measured results indicate a chemical sensitivity of 28 mV/pH, and relatively low leakage currents (2–10 nA) and drifts (1–10 mV/h). The proposed sensing device demonstrates the possibility of a low-cost implementation that can be reusable and thus versatile, with potential applications in real-time extracellular but mainly intracellular chemical monitoring.

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• Journal article
  Eftekhar A, Toumazou C, Drakakis EM, 2013,

  Empirical Mode Decomposition: Real-Time Implementation and Applicationss

  , Journal of Signal Processing Systems, Vol: 73, Pages: 43-58, ISSN: 1939-8018
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• Conference paper
  Leene L, Liu Y, Constandinou TG, 2013,

  A Compact Recording Array for Neural Interfaces

  , IEEE Biomedical Circuits and Systems (BioCAS) Conference

  This paper presents a 44-channel front-end neural interface for recording both Extracellular Action Potentials (EAPs) and Local Field Potentials (LFPs) with 60dB dynamic range. With a silicon footprint of only 0.011mm² per recording channel this allows an unprecedented order of magnitude area reduction over state-of-the-art implementations in 0.18μm CMOS. This highly compact configuration is achievable by introducing an in-channel Sigma Delta assisted Successive Approximation Register (ΣΔ-SAR) hybrid data converter integrated into the analogue front-end. A pipelined low complexity FIR filter is distributed across 44-channels to resolve a 10-bit PCM output. The proposed system achieves an input referred noise of 6.41μVrms with a 6kHz bandwidth and sampled at 12.5kS/s, with a power consumption of 2.6μW per channel.

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• Journal article
  Berdan R, Prodromakis T, Salaoru I, Khiat A, Toumazou Cet al., 2012,

  Memristive devices as parameter setting elements in programmable gain amplifiers

  , APPLIED PHYSICS LETTERS, Vol: 101, ISSN: 0003-6951
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  • Citations: 24
• Journal article
  Herrero P, Calm R, Vehi J, Armengol J, Gerogiou P, Oliver N, Toumazou Cet al., 2012,

  Robust Fault Detection System For Insulin Pump Therapy using Continuous Glucose Monitoring

  , Journal of Diabetes Science and Technology, Vol: 6, Pages: 1131-1141

  Background:The popularity of continuous subcutaneous insulin infusion (CSII), or insulin pump therapy, as a way to deliver insulin more physiologically and achieve better glycemic control in diabetes patients has increased. Despite the substantiated therapeutic advantages of using CSII, its use has also been associated with an increased risk of technical malfunctioning of the device, which leads to an increased risk of acute metabolic complications, such as diabetic ketoacidosis. Current insulin pumps already incorporate systems to detect some types of faults, such as obstructions in the infusion set, but are not able to detect other types of fault such as the disconnection or leakage of the infusion set. Methods:In this article, we propose utilizing a validated robust model-based fault detection technique, based on interval analysis, for detecting disconnections of the insulin infusion set. For this purpose, a previously validated metabolic model of glucose regulation in type 1 diabetes mellitus (T1DM) and a continuous glucose monitoring device were used. As a first step to assess the performance of the presented fault detection system, a Food and Drug Administration-accepted T1DM simulator was employed.Results:Of the 100 in silico tests (10 scenarios on 10 subjects), only two false negatives and one false positive occurred. All faults were detected before plasma glucose concentration reached 300 mg/dl, with a mean plasma glucose detection value of 163 mg/dl and a mean detection time of 200 min.Conclusions:Interval model-based fault detection has been proven (in silico) to be an effective tool for detecting disconnection faults in sensor-augmented CSII systems. Proper quantification of the uncertainty associated with the employed model has been observed to be crucial for the good performance of the proposed approach.

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• Journal article
  Berdan R, Prodromakis T, Toumazou C, 2012,

  High precision analogue memristor state tuning

  , ELECTRONICS LETTERS, Vol: 48, Pages: 1105-1106, ISSN: 0013-5194
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  • Citations: 36
• Conference paper
  Paraskevopoulou SE, Constandinou TG, 2012,

  An Ultra-Low-Power Front-End Neural Interface with Automatic Gain for Uncalibrated Monitoring

  , International Symposium on Circuits and Systems (ISCAS), ISSN: 0271-4302

  This paper presents a dynamic front-end towards achieving unsupervised single-neuron activity monitoring. By implementing at the front-end, an automatic gain control that is optimised for neural signal dynamics, subsequent processing can be achieved without the need for calibration. The system uses three amplification stages (low-noise first stage, variable-gain second stage and high-gain third stage), a tuneable high-pass filter, and a feedback loop to tune the variable gain. The circuit has been implemented in a commercially-available 0.18um CMOS technology with total power consumption between 1.79 and 1.95$uW$ The front-end achieves a variable gain from 52 to 86.4dB with 3kHz bandwidth and a high-pass filter that is tuneable from 100-300Hz. The input referred noise is 9.66uV with a total harmonic distortion of under 1%.

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• Conference paper
  Haaheim B, Constandinou TG, 2012,

  A Sub-1μW, 16kHz Current-Mode SAR-ADC for Neural Spike Recording

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

  This paper presents an ultra-low-power 8-bit asynchronous current-mode (CM) successive approximation (SAR) analogue-to-digital converter (ADC) for single-neuron spike recording. The novel design exploits CM techniques to support operation at supply voltages down to 1.2V, consuming under500nA at 16kSamples/s. The design features easy scalability, and allows for a tuneable sampling frequency and dynamic range (DR). The circuit is designed in a commercially-available 0.18u mCMOS technology and occupies a chip area of 0.078 sq.mm. The system requires a single, post-fabrication current calibration supportedby on-chip circuitry to ensure robust operation through process and mismatch variations.

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• Conference paper
  Mirza KB, Luan S, Constandinou TG, 2012,

  Towards a Fully-Integrated Solution for Capacitor-Based Neural Stimulation

  , International Symposium on Circuits and Systems (ISCAS), ISSN: 0271-4302

  Charge-mode stimulation (ChgMS) is a relatively new method being explored in the field of electrical neural stimulation. One of the key challenges in such a system is to overcome charge sharing between the storage capacitor and the double layer capacitor in the Electrode-Electrolyte-Interface (EEI). In this work, this issue is overcome by using a second-generation negative current conveyor (CCII-) with low current tracking error. The level of charge sharing in the circuit is expressed by a new figure of merit (charge delivery efficiency) introduced in this paper. The proposed system has a maximum power efficiency of 76.6% and a total power consumption of 270uW per electrode for a target charge stimulus of 0.9nC. Crucially, the system achieves a minimum charge delivery efficiency of 98.22%.

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• Conference paper
  Luan S, Constandinou TG, 2012,

  A Novel Charge-Metering Method for Voltage Mode Neural Stimulation

  , International Symposium on Circuits and Systems (ISCAS), ISSN: 0271-4302

  This paper presents a novel, fully-integrated circuit for achieving change-balanced voltage-mode neural stimulation based on a charge-metering technique. The proposed system uses two small on-chip capacitors, a counter, two comparators and a control-logic circuit to measure the charge delivered to the tissue. The circuit has been designed to deliver a maximum charge of 10.24nC to the tissue within 100us. It is shown that the charge delivery error is 0.4-4% with a maximum residual charge of -73pC. Implemented in a standard 0.18um CMOS technology, the total power consumption is 42uW (excluding stimulus).

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• Conference paper
  Guilvard A, Eftekhar A, Luan S, Toumazou C, Constandinou TGet al., 2012,

  A Fully-Programmable Neural Interface for Multi-Polar, Multi-Channel Stimulation Strategies

  , International Symposium on Circuits and Systems (ISCAS), ISSN: 0271-4302

  This paper describes a novel integrated electrodeinterface for multi-polar stimulation of multi-electrode arrays. This interface allows for simultaneous stimulation using multiple electrodes configured as source or sink with different phase and amplitudes in order to perform field shaping inside the tissue. The system is designed in an high voltage 0.18 μm CMOS process with 8 channels. It features an output voltage swing of 16V and current up to 0.5mA for electrode impedences of up to 30kΩ which is suitable for cuff and cortical grid arrays. This electrode interface comprise a digital module which stores stimulation settings and operates the different electrode channels. Here we present the full system architecture and simulation results.

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• Conference paper
  Williams I, Constandinou TG, 2012,

  An Energy-Efficient, Dynamic Voltage Scaling Neural Stimulator for a Proprioceptive Prosthesis

  , International Symposium on Circuits and Systems (ISCAS), ISSN: 0271-4302

  This paper presents an energy-efficient neuralstimulator capable of providing charge-balanced asymmetric pulses. Power consumption is reduced by implementing a fully-integrated DC-DC converter that uses a reconfigurable switched capacitor topology to provide 4 output voltages for DynamicVoltage Scaling (DVS). DC conversion efficiencies of between 63% and 76% are achieved using integrated capacitances of under 1nF and the DVS approach offers power savings of up to 53.5%compared to the front end of a typical current controlled neural stimulator. Charge balancing is achieved to a low level of accuracy on a single pulse and a much higher accuracy over a series ofpulses. The method used is robust to process and component variation and does not require any initial or ongoing calibration. Monte-Carlo simulations indicate that the charge imbalance willbe less than 0.014% (at 3 sigma ) of charge delivered for a series of pulses. The circuit has been designed in a commercially-available0.18 m HV CMOS technology and requires a die areaof <0.5 sq. mm for a 16 channel implementation.

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