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Journal articleConstandinou TG, Hafliger P, 2010,
Guest Editorial - Special Issue on Selected Papers from ISCAS 2009
, IEEE Transactions on Biomedical Circuits and Systems, Vol: 4, Pages: 137-138, ISSN: 1932-4545 -
Conference paperConstandinou TG, Georgiou P, Prodromakis T, et 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: 1-6This 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 à 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.
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Conference paperGarner DM, Bai H, Georgiou P, et al., 2010,
A multichannel DNA SoC for rapid point-of-care gene detection
, IEEE International Solid-State Circuits Conference (ISSCC), Publisher: IEEE, Pages: 492 -493-492 -493, ISSN: 0193-6530 -
Conference paperEftekhar 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: 122-125In 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.
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Journal articleConstandinou TG, Georgiou J, 2009,
A Micropower Tilt Processing Circuit
, IEEE Transactions on Biomedical Circuits and Systems, Vol: 3, Pages: 363-369, ISSN: 1932-4545This paper describes a novel analogue circuit for extracting the tilt angle from the output of a linear MEMS accelerometer. The circuit uses the accelerometer signal together with the gravitational acceleration vector to generate the tilt signal. Using a current-mode representation with MOS devices operating in weak inversion, the appropriate trigonometric function has been realised to compute tilt. Furthermore, implementing a long-time constant filter to extract the mean tilt level provides adaptation to the static tilt level. Specifically, this circuit has been designed as part of an implantable vestibular prosthesis to provide inclination signals for bypassing dysfunctional otolith end-organs. The circuit has been fabricated in AMS 0.35um 2P4M CMOS technology and this paper presents the theory, implementation and measured results.
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BookConstandinou TG, 2009,
Biologically Inspired Electronics for Micropower Vision Processing
, Publisher: VDM Verlag, ISBN: 978-3639133912 -
Conference paperEftekhar A, Constandinou TG, Abbruzzese D, et al., 2009,
A Programmable Neural Interface for Investigating Arbitrary Stimulation Strategies
, 14th Annual International FES Society Conference -
Conference paperConstandinou 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 -
Conference paperLiu Y, Georgiou P, Constandinou TG, et al., 2009,
An Auto-Offset-Removal circuit for chemical sensing based on the PG-ISFET
, IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 1165-1168 -
Conference paperConstandinou TG, Georgiou J, 2008,
A Micropower Tilt Processing Circuit
, IEEE Biomedical Circuits and Systems (BioCAS) Conference, Publisher: IEEE, Pages: 197-200This paper describes a novel analogue circuit for extracting the tilt angle from the output of a standard MEMS accelerometer. The circuit uses the accelerometer signal together with the gravitational acceleration vector to generate the tilt signal. Using a current-mode representation with devices operated in subthreshold, the appropriate trigonometric function has been realised to compute tilt. Furthermore, implementing a long-time constant filter to extract the mean tilt level provides adaptation to the static tilt level. Specifically, this circuit has been designed as part of an implantable vestibular prosthesis to provide inclination signals for bypassing dysfunctional otolith end-organs. The hardware has been implemented in AMS 0.35 mum 2P4M CMOS technology.
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Journal articleConstandinou TG, Georgiou J, 2008,
A Micropower Arcsine Circuit for Tilt Processing
, Electronics Letters, Vol: 44, Pages: 1336-1338, ISSN: 0013-5194This 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.
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Journal articleConstandinou 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: 1932-4545This 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.
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Journal articleConstandinou TG, Georgiou J, Toumazou C, 2008,
Micropower front-end interface for differential-capacitive sensor systems
, Electronics Letters, Vol: 44, Pages: 470-472, ISSN: 0013-5194A front-end circuit for interfacing to differential capacitive sensors, including certain microelectromechanical systems, is presented. The system combines a self-resetting, biphasic integrator with a difference timer, producing a word parallel output representing the differential capacitance. The measurable capacitance range is tunable by means of an input current bias and system clock frequency. For an input bias of 10 nA and system clock of 128 KHz, the measurable capacitance range is +/-5pF (to 8 bit resolution) consuming below 26 µW total system power.
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Conference paperProdromakis T, Georgiou P, Constandinou TG, et al., 2008,
Batch Encapsulation Technique for CMOS based Chemical Sensors
, IEEE Biomedical Circuits and Systems (BioCAS) Conference, Publisher: IEEE, Pages: 321-324 -
Journal articleConstandinou TG, Georgiou J, 2008,
Micro-Optoelectromechanical Tilt Sensor
, Journal of Sensors, Pages: 1-7, ISSN: 1687-725XThis 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.
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Journal articleConstandinou 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: 210-215Neuroprosthetics 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.
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Conference paperConstandinou TG, Georgiou J, Andreou C, 2008,
An Ultra-Low-Power Micro-Optoelectromechanical Tilt Sensor
, IEEE International Symposium on Circuits and Systems (ISCAS), Pages: 3158-3161 -
Conference paperConstandinou TG, Georgiou J, Toumazou C, 2008,
A Micropower Front-end Interface for Differential-Capacitive Sensor Systems
, IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 2474-2477 -
Conference paperConstandinou 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 -
Conference paperConstandinou 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
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