By Topic

Biomedical Circuits and Systems, IEEE Transactions on

Issue 1 • Date Feb. 2012

Filter Results

Displaying Results 1 - 12 of 12
  • Table of contents

    Publication Year: 2012 , Page(s): C1
    Save to Project icon | Request Permissions | PDF file iconPDF (69 KB)  
    Freely Available from IEEE
  • IEEE Transactions on Biomedical Circuits and Systems publication information

    Publication Year: 2012 , Page(s): C2
    Save to Project icon | Request Permissions | PDF file iconPDF (41 KB)  
    Freely Available from IEEE
  • An Energy-Efficient, Adiabatic Electrode Stimulator With Inductive Energy Recycling and Feedback Current Regulation

    Publication Year: 2012 , Page(s): 1 - 14
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1052 KB) |  | HTML iconHTML  

    In this paper, we present a novel energy-efficient electrode stimulator. Our stimulator uses inductive storage and recycling of energy in a dynamic power supply. This supply drives an electrode in an adiabatic fashion such that energy consumption is minimized. It also utilizes a shunt current-sensor to monitor and regulate the current through the electrode via feedback, thus enabling flexible and safe stimulation. Since there are no explicit current sources or current limiters, wasteful energy dissipation across such elements is naturally avoided. The dynamic power supply allows efficient transfer of energy both to and from the electrode and is based on a DC-DC converter topology that we use in a bidirectional fashion in forward-buck or reverse-boost modes. In an exemplary electrode implementation intended for neural stimulation, we show how the stimulator combines the efficiency of voltage control and the safety and accuracy of current control in a single low-power integrated-circuit built in a standard .35 μm CMOS process. This stimulator achieves a 2x-3x reduction in energy consumption as compared to a conventional current-source-based stimulator operating from a fixed power supply. We perform a theoretical analysis of the energy efficiency that is in accord with experimental measurements. This theoretical analysis reveals that further improvements in energy efficiency may be achievable with better implementations in the future. Our electrode stimulator could be widely useful for neural, cardiac, retinal, cochlear, muscular and other biomedical implants where low power operation is important. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • High-Level Energy Estimation in the Sub-V _{{\rm T}} Domain: Simulation and Measurement of a Cardiac Event Detector

    Publication Year: 2012 , Page(s): 15 - 27
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1266 KB) |  | HTML iconHTML  

    This paper presents a flow that is suitable to estimate energy dissipation of digital standard-cell based designs which are determined to operate in the subthreshold regime. The flow is applicable on gate-level netlists, where back-annotated toggle information is used to find the minimum energy operation point, corresponding maximum clock frequency, as well as the dissipated energy per clock cycle. The application of the model is demonstrated by exploring the energy efficiency of pipelining, retiming, and register balancing. Simulation results, which are obtained during a fraction of SPICE simulation time, are validated by measurements on a wavelet-based cardiac event detector that was fabricated in 65-nm low-leakage high-threshold technology. The mean of the absolute modeling error is calculated as 5.2%, with a standard deviation of 6.6% over the measurement points. The cardiac event detector dissipates 0.88 pJ/sample at a supply voltage of 320 mV. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Wireless Front-End With Power Management for an Implantable Cardiac Microstimulator

    Publication Year: 2012 , Page(s): 28 - 38
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1948 KB) |  | HTML iconHTML  

    Inductive coupling is presented with the help of a high-efficiency Class-E power amplifier for an implantable cardiac microstimulator. The external coil inductively transmits power and data with a carrier frequency of 256 kHz into the internal coil of electronic devices inside the body. The detected cardiac signal is fed back to the external device with the same pair of coils to save on space in the telemetry device. To maintain the power reliability of the microstimulator for long-term use, two small rechargeable batteries are employed to supply voltage to the internal circuits. The power management unit, which includes radio frequency front-end circuits with battery charging and detection functions, is used for the supply control. For cardiac stimulation, a high-efficiency charge pump is also proposed in the present paper to generate a stimulated voltage of 3.2 V under a 1 V supply voltage. A phase-locked-loop (PLL)-based phase shift keying demodulator is implemented to efficiently extract the data and clock from an inductive AC signal. The circuits, with an area of 0.45 mm2, are implemented in a TSMC 0.35 μm 2P4M standard CMOS process. Measurement results reveal that power can be extracted from the inductive coupling and stored in rechargeable batteries, which are controlled by the power management unit, when one of the batteries is drained. Moreover, the data and clock can be precisely recovered from the coil coupling, and a stimulated voltage of 3.2 V can be readily generated by the proposed charge-pump circuits to stimulate cardiac tissues. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A New Dual Current-Mode Controller Improves Power Regulation in Electrosurgical Generators

    Publication Year: 2012 , Page(s): 39 - 44
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1351 KB) |  | HTML iconHTML  

    A new dual current-mode controller produces a fast, accurate constant-power high-frequency ac output, with maximum current and voltage limits for an electrosurgical generator. The regulation of ac output power is achieved with near-deadbeat control, without measurement or feedback of the output voltage or current. Compared to existing technology, the prototype generator reduces unintended tissue damage by significantly improving regulation of output power, while reducing complexity and parts count. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An Electronic Patch for Wearable Health Monitoring by Reflectance Pulse Oximetry

    Publication Year: 2012 , Page(s): 45 - 53
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1127 KB) |  | HTML iconHTML  

    We report the development of an Electronic Patch for wearable health monitoring. The Electronic Patch is a new health monitoring system incorporating biomedical sensors, microelectronics, radio frequency (RF) communication, and a battery embedded in a 3-dimensional hydrocolloid polymer. In this paper the Electronic Patch is demonstrated with a new optical biomedical sensor for reflectance pulse oximetry so that the Electronic Patch in this case can measure the pulse and the oxygen saturation. The reflectance pulse oximetry solution is based on a recently developed annular backside silicon photodiode to enable low power consumption by the light emitting components. The Electronic Patch has a disposable part of soft adhesive hydrocolloid polymer and a reusable part of hard polylaurinlactam. The disposable part contains the battery. The reusable part contains the reflectance pulse oximetry sensor and microelectronics. The reusable part is 'clicked' into the disposable part when the patch is prepared for use. The patch has a size of 88 mm by 60 mm and a thickness of 5 mm. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Onboard Tagging for Real-Time Quality Assessment of Photoplethysmograms Acquired by a Wireless Reflectance Pulse Oximeter

    Publication Year: 2012 , Page(s): 54 - 63
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1659 KB) |  | HTML iconHTML  

    Onboard assessment of photoplethysmogram (PPG) quality could reduce unnecessary data transmission on battery-powered wireless pulse oximeters and improve the viability of the electronic patient records to which these data are stored. These algorithms show promise to increase the intelligence level of former “dumb” medical devices: devices that acquire and forward data but leave data interpretation to the clinician or host system. To this end, the authors have developed a unique onboard feature detection algorithm to assess the quality of PPGs acquired with a custom reflectance mode, wireless pulse oximeter. The algorithm uses a Bayesian hypothesis testing method to analyze four features extracted from raw and decimated PPG data in order to determine whether the original data comprise valid PPG waveforms or whether they are corrupted by motion or other environmental influences. Based on these results, the algorithm further calculates heart rate and blood oxygen saturation from a “compact representation” structure. PPG data were collected from 47 subjects to train the feature detection algorithm and to gauge their performance. A MATLAB interface was also developed to visualize the features extracted, the algorithm flow, and the decision results, where all algorithm-related parameters and decisions were ascertained on the wireless unit prior to transmission. For the data sets acquired here, the algorithm was 99% effective in identifying clean, usable PPGs versus nonsaturated data that did not demonstrate meaningful pulsatile waveshapes, PPGs corrupted by motion artifact, and data affected by signal saturation. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Small-Signal Neural Models and Their Applications

    Publication Year: 2012 , Page(s): 64 - 75
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1060 KB) |  | HTML iconHTML  

    This paper introduces the use of the concept of small-signal analysis, commonly used in circuit design, for understanding neural models. We show that neural models, varying in complexity from Hodgkin-Huxley to integrate and fire have similar small-signal models when their corresponding differential equations are close to the same bifurcation with respect to input current. Three applications of small-signal neural models are shown. First, some of the properties of cortical neurons described by Izhikevich are explained intuitively through small-signal analysis. Second, we use small-signal models for deriving parameters for a simple neural model (such as resonate and fire) from a more complicated but biophysically relevant one like Morris-Lecar. We show similarity in the subthreshold behavior of the simple and complicated model when they are close to a Hopf bifurcation and a saddle-node bifurcation. Hence, this is useful to correctly tune simple neural models for large-scale cortical simulations. Finaly, the biasing regime of a silicon ion channel is derived by comparing its small-signal model with a Hodgkin-Huxley-type model. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Modeling and Implementation of Voltage-Mode CMOS Dendrites on a Reconfigurable Analog Platform

    Publication Year: 2012 , Page(s): 76 - 84
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (548 KB) |  | HTML iconHTML  

    Many decades ago, Wilfrid Rall and others laid the foundations for mathematical modeling of dendrites using cable theory. With reconfigurable analog architectures, we are now able to accurately program different circuit architectures to emulate dendrites. Our work has shown that these circuits accurately reproduce results predicted from cable theory when inputs to the system are small. For large inputs, interesting nonlinear effects begin to take hold. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • IEEE Transactions on Biomedical Circuits and Systems society information

    Publication Year: 2012 , Page(s): C3
    Save to Project icon | Request Permissions | PDF file iconPDF (27 KB)  
    Freely Available from IEEE
  • [Blank page]

    Publication Year: 2012 , Page(s): C4
    Save to Project icon | Request Permissions | PDF file iconPDF (5 KB)  
    Freely Available from IEEE

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.

Full Aims & Scope

Meet Our Editors

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