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  • Patent
    Georgiou P, Prodromakis T, Constandinou TG, Toumazou Cet al., 2011,

    Sensor Array for Measuring Neural Activity

    A sensor system comprising a substrate and integrated onto the substrate an array (7) of sensor elements (1), each sensor element comprising one or more inductors (3), one or more electrochemical sensors (4), and one or more optical sensors (2). The system further comprising a controller configured in use to separately address each of the sensor elements (1) to drive the respective inductors and receive outputs of the respective sensors.
  • Conference paper
    Sole M, Sanni A, Vilches A, Toumazou C, Constandinou TGet al., 2011,

    A Bio-Implantable Platform for Inductive Data and Power Transfer with Integrated Battery Charging

    , IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 2605-2608

    This paper describes a mixed signal subsystem for the inductive transfer of power and data to a fully-implantable medical device. The design includes circuits for the inductive power recovery and energy storage (charging), in addition to data recovery and demodulation. The data link is used to upload (at a data rate of up to 180Kbps) calibration and configuration data to the implanted device and integrates both error detection and correction on the recovered bitstream. The system incorporates an implanted Li-Ion micro-battery with supporting charging hardware to provide an uninterrupted power supply for autonomous deployment. This is to provide continuous operation without the requirement for an externally worn unit and additionally ensures registry (i.e. patient calibration) settings are maintained. The circuit has been implemented in a commercially available 0.35um CMOS technology without requiring high-voltage device options.
  • Conference paper
    Paraskevopoulou S, Constandinou TG, 2011,

    A sub-1μW Neural Spike-Peak Detection and Spike-Count Rate Encoding Circuit

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

    In this paper we present a circuit for determining neural spike features such as peak occurrence, peak amplitude and spike count rate in continuous-time. The system achieves these functions concurrently and in real-time achieving an accuracy higher than a typical digital solution (constrained by a the sampling time and/or resolution). For an average spike rate of 50$spikes/s$ the system consumes 815nW designed in a commercially-available 0.18μm CMOS technology. The complete circuit core (excluding bondpads) occupies a total area of approximately 0.022mm²
  • Conference paper
    Luan S, Eftekhar A, Murphy O, Constandinou TGet al., 2011,

    Towards an Inductively Coupled Power/Data Link for Bondpad-Less Silicon Chips

    , IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 7-10

    This paper explores the concept of developing a bondpad-less fullyintegrated inductive link for power/data transfer between a silicon chip and a PCB. A key feature of the implemented system is that it requires no off-chip components. The proposed chip uses a standard 0.35um process and occupies an area of 2.5 x 2.5 mm^2. 9mW power was designed to be obtained on-chip through 900MHz carrier wave. Binary Phase Shift Keying (BPSK) and Load shift keying (LSK) are used for the the PCB-to-chip and chip-to-PCB link respectively for half-duplex communication.
  • Conference paper
    Constandinou TG, Georgiou P, Prodromakis T, Toumazou Cet al., 2010,

    A CMOS-based Lab-on-Chip Array for the Combined Magnetic Stimulation and Opto-Chemical Sensing of Neural Tissue

    , Berkeley, CA, 2010 12th International Workshop on Cellular Nanoscale Networks and their Applications (CNNA), Publisher: IEEE, Pages: 1-6

    This paper presents a novel CMOS-based lab-on-chip platform for non-contact magnetic stimulation and recording of neural tissue. The proposed system is the first of its kind to integrate magnetic-stimulation and opto-chemical sensing in a single pixel, tesselated to form an 8 × 8 array. Fabricated in a commercially-available 0.35 ¿m CMOS technology, the system can be intrinsically used for both optical imaging and pH sensing and includes mechanisms for calibrating out sensor variation and mismatch. In addition to sensory acquisition via an integrated 10-bit ADC, a 64-instruction spatiotemporal pattern generator has been embedded within the array for driving the microscale magnetic neural stimulation. In this application the ISFET-based sensors are used to capacitively-couple neuronal charge in close proximity to the floating gate. Optical imaging hardware has also been embedded to provide topographic detail of the neural tissue.
  • Conference paper
    Eftekhar A, Paraskevopoulou S, Constandinou TG, 2010,

    Towards Next Generation Neural Interfaces: Optimizing Power, Bandwidth and Data Quality

    , IEEE Biomedical Circuits and Systems (BioCAS) Conference, Publisher: IEEE, Pages: 122-125

    In this paper, we review the state-of-the-art in neural interface recording architectures. Through this we identify schemes which show the trade-off between data information quality (lossiness), computation (i.e. power and area requirements) and the number of channels. These trade-offs are then extended by considering the front-end amplifier bandwidth to also be a variable. We therefore explore the possibility of band-limiting the spectral content of recorded neural signals (to save power) and investigate the effect this has on subsequent processing (spike detection accuracy). We identify the spike detection method most robust to such signals, optimize the threshold levels and modify this to exploit such a strategy.
  • Conference paper
    Eftekhar A, Constandinou TG, Abbruzzese D, Woods V, Triantis IF, Drakakis EM, Toumazou Cet al., 2009,

    A Programmable Neural Interface for Investigating Arbitrary Stimulation Strategies

    , 14th Annual International FES Society Conference
  • Conference paper
    Constandinou TG, Georgiou J, Toumazou C, 2009,

    A Neural Implant ASIC for the Restoration of Balance in Individuals with Vestibular Dysfunction

    , IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 641-644
  • Journal article
    Constandinou TG, Georgiou J, 2008,

    A Micropower Arcsine Circuit for Tilt Processing

    , Electronics Letters, Vol: 44, Pages: 1336-1338, ISSN: 0013-5194

    This letter describes an analogue circuit for producing an arcsine transfer based on a differential pair with source degeneration. The application uses this circuit to post-process an accelerometer signal by normalising with respect to the gravitational acceleration vector to extract inclination. Using diode-connected MOS devices operating in weak inversion, the appropriate trigonometric function, i.e. an arcsine, has been realised to compute tilt. The hardware has been implemented in AMS 0.35μm 2P4M CMOS technology.
  • Journal article
    Constandinou TG, Georgiou J, Toumazou C, 2008,

    A Partial-Current-Steering Biphasic Stimulation Driver for Vestibular Prostheses

    , IEEE Transactions on Biomedical Circuits and Systems, Vol: 2, Pages: 106-113, ISSN: 1932-4545

    This paper describes a novel partial-current-steering stimulation circuit for implantable vestibular prostheses. The drive hardware momentarily delivers a charge-balanced asymmetric stimulus to a dummy load before steering towards the stimulation electrodes. In this fashion, power is conserved while still gaining from the benefits of current steering. The circuit has been designed to be digitally programmable as part of an implantable vestibular prosthesis. The hardware has been implemented in AMS 0.35μm 2P4M CMOS technology.
  • Journal article
    Constandinou TG, Georgiou J, Toumazou C, 2008,

    Towards an Integrated, Fully-Implantable Vestibular Prosthesis for Balance Restoration

    , Journal of Advances in Science and Technology, Vol: 57, Pages: 210-215

    Neuroprosthetics is a relatively new topic but it has already shown its potential. Since the application of this science, it has already significantly improved the quality of life of over 60,000 individuals who previously suffered from severely impaired hearing or total deafness. Today, through use of cochlear implants, children born totally deaf can enjoy going to regular schools and communicating normally. Individuals suffering from dizziness and balance disorders can also benefit from the progress made in cochlear prosthetics. The inner ear's vestibular system provides cues about self-motion and help stabilise vision during movement. Damage to this system can result in dizziness, imbalance, blurred vision and instability in locomotion, a leading cause of death in the elderly. We propose a hybrid CMOS/MEMS platform for bypassing a dysfunctional pathway in individuals that suffer from balance-related disorders. Combining MEMS-based inertia sensing with CMOS-based neural monitoring and processing electronics, this prosthesis aims to deliver a corrective artificial stimulus to the vestibulocochlear (VIII) nerve. We describe a novel system outlining the architectural aspects and implementation methodology used in the design.
  • Conference paper
    Constandinou TG, Georgiou J, Toumazou C, 2008,

    A Fully-Integrated Semicircular Canal Processor for an Implantable Vestibular Prosthesis

    , IEEE International Conference on Electronics, Circuits and Systems (ICECS), Publisher: IEEE, Pages: 81-84
  • Conference paper
    Constandinou TG, Georgiou J, Toumazou C, 2008,

    A Partial-Current-Steering Biphasic Stimulation Driver for Neural Prostheses

    , IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 2506-2509
  • Journal article
    Constandinou TG, Georgiou J, 2008,

    Micro-Optoelectromechanical Tilt Sensor

    , Journal of Sensors, Pages: 1-7, ISSN: 1687-725X

    This paper presents a novel hybrid CMOS/MEMS tilt sensor with a 5∘ resolution over a 300∘ range. The device uses a MEMS-based semicircular mass suspended from a rigid body, projecting a shadow onto the CMOS-based optical sensor surface. A one-dimensional photodiode array arranged as a uniformly segmented ring is then used to determine the tilt angle by detecting the position of the semicircular mass. The complete sensor occupies an area of under 2.5 mm × 2.5 mm.
  • Journal article
    Lande TS, Constandinou TG, Burdett A, Toumazou Cet al., 2007,

    Running cross-correlation using bitstream processing

    , Electronics Letters, Vol: 43, Pages: 1181-1183, ISSN: 0013-5194

    A novel architecture for running cross-correlation and convolution using bitstream processing is proposed. The computationally intensive multiplications inherent in cross-correlation and convolution are replaced by simple logic operations (AND XOR) using bitstream representation. The reduced complexity enables compact and energy efficient silicon solutions suitable for small, portable devices such as wearable heartbeat detecting electronics embedded in the actual ECG patch.
  • Journal article
    Triantis IF, Woods V, Eftekhar A, Georgiou P, Constandinou TG, Drakakis EM, Toumazou Cet al., 2007,

    Advances in Neural Interfacing

    , IEEE Circuits and Systems Society Newsletter, Vol: 1
  • Conference paper
    Eftekhar A, Constandinou TG, Triantis IF, Toumazou C, Drakakis EMet al., 2007,

    Towards a Reconfigurable Sense-and-Stimulate Neural Interface Generating Biphasic Interleaved Stimulus

    , 3rd International IEEE/EMBS Conference on Neural Engineering (CNE), Publisher: IEEE, Pages: 438-441
  • Conference paper
    Li X, Constandinou TG, Eftekhar A, Georgiou P, Toumazou Cet al., 2007,

    Towards a bionic neural link for implantable prosthetics

    , IEEE EMBS Conference on Neural Engineering, Publisher: Institute of Electrical and Electronics Engineers (IEEE), Pages: 85-88
  • Conference paper
    Constandinou TG, Georgiou J, Doumanidis CC, Tournazou Cet al., 2007,

    Towards an Implantable vestibular prosthesis: The surgical challenges

    , 3rd International IEEE/EMBS Conference on Neural Engineering, Publisher: IEEE, Pages: 40-+
  • Conference paper
    Georgiou J, Constandinou TG, Toumazou C, 2007,

    A Micropower Cochlear Prosthesis System Demonstrator

    , IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: Institute of Electrical and Electronics Engineers (IEEE), Pages: 1219-1219
  • Journal article
    Faisal AA, White JA, Laughlin SB,

    Supplemental Data Ion-Channel Noise Places Limits on the Miniaturization of the Brain’s Wiring

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