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Biomedical Circuits and Systems, IEEE Transactions on

Issue 4 • Date Aug. 2012

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Displaying Results 1 - 16 of 16
  • Table of contents

    Page(s): C1
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  • IEEE Transactions on Biomedical Circuits and Systems publication information

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  • Inductive and Ultrasonic Multi-Tier Interface for Low-Power, Deeply Implantable Medical Devices

    Page(s): 297 - 308
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2117 KB) |  | HTML iconHTML  

    We report the development of a novel multi-tier interface which enables the wireless, noninvasive transfer of sufficient amounts of power as well as the collection and transmission of data from low-power, deeply implantable analog sensors. The interface consists of an inductive coupling subsystem and an ultrasonic subsystem. The designed and experimentally verified inductive subsystem ensures that 5 W of power is transferred across 10 mm of air gap between a single pair of PCB spiral coils with an efficiency of 83% using our prototype CMOS logic gate-based driver circuit. The implemented ultrasonic subsystem, based on ultrasonic PZT ceramic discs driven in their low-frequency, radial/planar-excitation mode, further ensures that 29 μW of power is delivered 70 mm deeper inside a homogenous liquid environment-with no acoustic matching layer employed-with an efficiency of 1%. Overall system power consumption is 2.3 W. The implant is intermittently powered every 800 msec; charging a capacitor which provides sufficient power for a duration of ~ 18 msec; sufficient for an implant μC operating at a frequency of 500 KHz to transmit a nibble (4 bits) of digitized sensed data. View full abstract»

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  • Toward A Fully Integrated Neurostimulator With Inductive Power Recovery Front-End

    Page(s): 309 - 318
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1555 KB) |  | HTML iconHTML  

    In order to investigate new neurostimulation strategies for micturition recovery in spinal cord injured patients, custom implantable stimulators are required to carry-on chronic animal experiments. However, higher integration of the neurostimulator becomes increasingly necessary for miniaturization purposes, power consumption reduction, and for increasing the number of stimulation channels. As a first step towards total integration, we present in this paper the design of a highly-integrated neurostimulator that can be assembled on a 21-mm diameter printed circuit board. The prototype is based on three custom integrated circuits fabricated in High-Voltage (HV) CMOS technology, and a low-power small-scale commercially available FPGA. Using a step-down approach where the inductive voltage is left free up to 20 V, the inductive power and data recovery front-end is fully integrated. In particular, the front-end includes a bridge rectifier, a 20-V voltage limiter, an adjustable series regulator (5 to 12 V), a switched-capacitor step-down DC/DC converter (1:3, 1:2, or 2:3 ratio), as well as data recovery. Measurements show that the DC/DC converter achieves more than 86% power efficiency while providing around 3.9-V from a 12-V input at 1-mA load, 1:3 conversion ratio, and 50-kHz switching frequency. With such efficiency, the proposed step-down inductive power recovery topology is more advantageous than its conventional step-up counterpart. Experimental results confirm good overall functionality of the system. View full abstract»

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  • A Magnetic Manipulation System Using an Active Filter for Electronic Detection of Target Cells

    Page(s): 319 - 325
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    Important advances in the development of magnetic manipulation devices have been recorded over the last few years and promising experimental results have been presented. In this article we first perform a detailed analysis on one of most widely used magnetic actuators, namely a planar microcoil. Key parameters that affect the performance of the actuator are identified and our results are in accordance with measured data. Making use of these findings, a lab-on-a-chip system is proposed, that also integrates a novel electronic sensing concept for live monitoring of its activity. Possible applications of this system include highly selective bioseparation or the possibility to manipulate and assemble marked particles with great precision. View full abstract»

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  • A High-Efficiency Low-Voltage CMOS Rectifier for Harvesting Energy in Implantable Devices

    Page(s): 326 - 335
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1106 KB) |  | HTML iconHTML  

    We present, in this paper, a new full-wave CMOS rectifier dedicated for wirelessly-powered low-voltage biomedical implants. It uses bootstrapped capacitors to reduce the effective threshold voltage of selected MOS switches. It achieves a significant increase in its overall power efficiency and low voltage-drop. Therefore, the rectifier is good for applications with low-voltage power supplies and large load current. The rectifier topology does not require complex circuit design. The highest voltages available in the circuit are used to drive the gates of selected transistors in order to reduce leakage current and to lower their channel on-resistance, while having high transconductance. The proposed rectifier was fabricated using the standard TSMC 0.18 μm CMOS process. When connected to a sinusoidal source of 3.3 V peak amplitude, it allows improving the overall power efficiency by 11% compared to the best recently published results given by a gate cross-coupled-based structure. View full abstract»

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  • A Photovoltaic-Driven and Energy-Autonomous CMOS Implantable Sensor

    Page(s): 336 - 343
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1868 KB) |  | HTML iconHTML  

    An energy-autonomous, photovoltaic (PV)-driven and MRI-compatible CMOS implantable sensor is presented. On-chip P+/N-well diode arrays are used as CMOS-compatible PV cells to harvest μW's of power from the light that penetrates into the tissue. In this 2.5 mm × 2.5 mm sub-μW integrated system, the in-vivo physiological signals are first measured by using a subthreshold ring oscillator-based sensor, the acquired data is then modulated into a frequency-shift keying (FSK) signal, and finally transmitted neuromorphically to the skin surface by using a pair of polarized electrodes. View full abstract»

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  • Design of Ultra-Low Power Biopotential Amplifiers for Biosignal Acquisition Applications

    Page(s): 344 - 355
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1968 KB) |  | HTML iconHTML  

    Rapid development in miniature implantable electronics are expediting advances in neuroscience by allowing observation and control of neural activities. The first stage of an implantable biosignal recording system, a low-noise biopotential amplifier (BPA), is critical to the overall power and noise performance of the system. In order to integrate a large number of front-end amplifiers in multichannel implantable systems, the power consumption of each amplifier must be minimized. This paper introduces a closed-loop complementary-input amplifier, which has a bandwidth of 0.05 Hz to 10.5 kHz, an input-referred noise of 2.2 μ Vrms, and a power dissipation of 12 μW. As a point of comparison, a standard telescopic-cascode closed-loop amplifier with a 0.4 Hz to 8.5 kHz bandwidth, input-referred noise of 3.2 μ Vrms, and power dissipation of 12.5 μW is presented. Also for comparison, we show results from an open-loop complementary-input amplifier that exhibits an input-referred noise of 3.6 μ Vrms while consuming 800 nW of power. The two closed-loop amplifiers are fabricated in a 0.13 μ m CMOS process. The open-loop amplifier is fabricated in a 0.5 μm SOI-BiCMOS process. All three amplifiers operate with a 1 V supply. View full abstract»

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  • A Multisensor Implant for Continuous Monitoring of Intracranial Pressure Dynamics

    Page(s): 356 - 365
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    In humans, intracranial pressure (ICP) is not only influenced by pathology, but also by orientation in space and body movements. Therefore, it is proposed to measure ICP dynamics and body acceleration simultaneously. An algorithm for acceleration analysis was developed to monitor orientation in space and allow more accurate examination of ICP dynamics during quiet periods. View full abstract»

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  • A Knowledge-Based Approach to Arterial Stiffness Estimation Using the Digital Volume Pulse

    Page(s): 366 - 374
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1221 KB) |  | HTML iconHTML  

    We have developed a knowledge based approach for arterial stiffness estimation. The proposed new approach reliably estimates arterial stiffness based on the analysis of age and heart rate normalized reflected wave arrival time. The proposed new approach reduces cost, space, technical expertise, specialized equipment, complexity, and increases the usability compared to recently researched noninvasive arterial stiffness estimators. The proposed method consists of two main stages: pulse feature extraction and linear regression analysis. The new approach extracts the pulse features and establishes a linear prediction equation. On evaluating proposed methodology with pulse wave velocity (PWV) based arterial stiffness estimators, the proposed methodology offered the error rate of 8.36% for men and 9.52% for women, respectively. With such low error rates and increased benefits, the proposed approach could be usefully applied as low cost and effective solution for ubiquitous and home healthcare environments. View full abstract»

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  • Image Sensor System With Bio-Inspired Efficient Coding and Adaptation

    Page(s): 375 - 384
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    We designed and implemented an image sensor system equipped with three bio-inspired coding and adaptation strategies: logarithmic transform, local average subtraction, and feedback gain control. The system comprises a field-programmable gate array (FPGA), a resistive network, and active pixel sensors (APS), whose light intensity-voltage characteristics are controllable. The system employs multiple time-varying reset voltage signals for APS in order to realize multiple logarithmic intensity-voltage characteristics, which are controlled so that the entropy of the output image is maximized. The system also employs local average subtraction and gain control in order to obtain images with an appropriate contrast. The local average is calculated by the resistive network instantaneously. The designed system was successfully used to obtain appropriate images of objects that were subjected to large changes in illumination. View full abstract»

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  • Spike-Timing-Dependent Plasticity With Weight Dependence Evoked From Physical Constraints

    Page(s): 385 - 398
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2175 KB) |  | HTML iconHTML  

    Analogue and mixed-signal VLSI implementations of Spike-Timing-Dependent Plasticity (STDP) are reviewed. A circuit is presented with a compact implementation of STDP suitable for parallel integration in large synaptic arrays. In contrast to previously published circuits, it uses the limitations of the silicon substrate to achieve various forms and degrees of weight dependence of STDP. It also uses reverse-biased transistors to reduce leakage from a capacitance representing weight. Chip results are presented showing: various ways in which the learning rule may be shaped; how synaptic weights may retain some indication of their learned values over periods of minutes; and how distributions of weights for synapses convergent on single neurons may shift between more or less extreme bimodality according to the strength of correlational cues in their inputs. View full abstract»

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    Page(s): 399
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  • IEEE Transactions on Biomedical Circuits and Systems information for authors

    Page(s): 400
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  • IEEE Transactions on Biomedical Circuits and Systems society information

    Page(s): C3
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  • [Blank page - Back cover]

    Page(s): C4
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Aims & Scope

IEEE Transactions on Biomedical Circuits and Systems (TBioCAS) publishes peer-reviewed manuscripts reporting original and transformative research at the intersection between the life sciences and circuits and systems engineering principles.

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Meet Our Editors

Editor-in-Chief
Gert Cauwenberghs
University of California at San Diego