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Biomedical Circuits and Systems, IEEE Transactions on

Issue 5 • Date Oct. 2012

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Displaying Results 1 - 19 of 19
  • Table of Contents

    Page(s): C1 - C4
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  • IEEE Transactions on Biomedical Circuits and Systems publication information

    Page(s): C2
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  • Guest Editorial—Special Issue on Selected Papers From BioCAS 2011

    Page(s): 401 - 402
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  • A 4 \mu{\rm W}/{\rm Ch} Analog Front-End Module With Moderate Inversion and Power-Scalable Sampling Operation for 3-D Neural Microsystems

    Page(s): 403 - 413
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2184 KB) |  | HTML iconHTML  

    We report an analog front-end prototype designed in 0.25 μm CMOS process for hybrid integration into 3-D neural recording microsystems. For scaling towards massive parallel neural recording, the prototype has investigated some critical circuit challenges in power, area, interface, and modularity. We achieved extremely low power consumption of 4 μW/channel, optimized energy efficiency using moderate inversion in low-noise amplifiers (K of 5.98 ×108 or NEF of 2.9), and minimized asynchronous interface (only 2 per 16 channels) for command and data capturing. We also implemented adaptable operations including programmable-gain amplification, power-scalable sampling (up to 50 kS/s/channel), wide configuration range (9-bit) for programmable gain and bandwidth, and 5-bit site selection capability (selecting 16 out of 128 sites). The implemented front-end module has achieved a reduction in noise-energy-area product by a factor of 5-25 times as compared to the state-of-the-art analog front-end approaches reported to date. View full abstract»

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  • Towards a Smart Experimental Arena for Long-Term Electrophysiology Experiments

    Page(s): 414 - 423
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    Wireless power and data transmission have created promising prospects in biomedical research by enabling perpetual data acquisition and stimulation systems. We present a work in progress towards such a system, called the EnerCage, equipped with scalable arrays of overlapping planar spiral coils (PSC) and 3-axis magnetic sensors for focused wireless power transmission to randomly moving targets, such as small freely behaving animal subjects. The EnerCage system includes a stationary unit for 3D non-line-of-sight localization and inductive power transmission through a geometrically optimized PSC array. The localization algorithm compares the magnetic sensor outputs with a threshold to activate a PSC. All PSCs are optimized based on the worst-case misalignment, considering parasitics from the overlapping and adjacent PSCs. EnerCage also has a mobile unit attached to or implanted in the subject's body, which includes a permanent magnetic tracer for localization and back telemetry circuit for efficient closed-loop inductive power regulation. The EnerCage system is designed to enable long-term electrophysiology experiments on freely behaving small animal subjects in large experimental arenas without requiring them to carry bulky batteries. A prototype of the EnerCage system with five PSCs and five magnetic sensors achieved power transfer efficiency (PTE) of 19.6% at the worst-case horizontal misalignment of 49.1 mm (√1/3 of the PSC radius) and coupling distance of 78 mm with a mobile unit coil, 20 mm in radius. The closed-loop power management mechanism maintains the mobile unit received power at 20 mW despite misalignments, tilting, and distance variations up to a maximum operating height of 120 mm (PTE=5%). View full abstract»

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  • A Battery-Free Multichannel Digital Neural/EMG Telemetry System for Flying Insects

    Page(s): 424 - 436
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    This paper presents a digital neural/EMG telemetry system small enough and lightweight enough to permit recording from insects in flight. It has a measured flight package mass of only 38 mg. This system includes a single-chip telemetry integrated circuit (IC) employing RF power harvesting for battery-free operation, with communication via modulated backscatter in the UHF (902-928 MHz) band. An on-chip 11-bit ADC digitizes 10 neural channels with a sampling rate of 26.1 kSps and 4 EMG channels at 1.63 kSps, and telemeters this data wirelessly to a base station. The companion base station transceiver includes an RF transmitter of +36 dBm (4 W) output power to wirelessly power the telemetry IC, and a digital receiver with a sensitivity of -70 dBm for 10-5 BER at 5.0 Mbps to receive the data stream from the telemetry IC. The telemetry chip was fabricated in a commercial 0.35 μ m 4M1P (4 metal, 1 poly) CMOS process. The die measures 2.36 × 1.88 mm, is 250 μm thick, and is wire bonded into a flex circuit assembly measuring 4.6 × 6.8 mm. View full abstract»

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  • A Miniaturized Platform for Laser Speckle Contrast Imaging

    Page(s): 437 - 445
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1417 KB) |  | HTML iconHTML  

    Imaging the brain in animal models enables scientists to unravel new biological insights. Despite critical advancements in recent years, most laboratory imaging techniques comprise of bulky bench top apparatus that require the imaged animals to be anesthetized and immobilized. Thus, animals are imaged in their non-native state severely restricting the scope of behavioral experiments. To address this gap, we report a miniaturized microscope that can be mounted on a rat's head for imaging in awake and unrestrained conditions. The microscope uses laser speckle contrast imaging (LSCI), a high resolution yet wide field imaging modality for imaging blood vessels and perfusion. Design details of both the image formation and acquisition modules are presented. A Monte Carlo simulation was used to estimate the depth of tissue penetration achievable by the imaging system while the produced speckle Airy disc patterns were simulated using Fresnel's diffraction theory. The microscope system weighs only 7 g and occupies less than 5 cm3 and was successfully used to generate proof of concept LSCI images of rat brain vasculature. We validated the utility of the head-mountable system in an awake rat brain model by confirming no impairment to the rat's native behavior. View full abstract»

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  • Design Constraints for Mobile, High-Speed Fluorescence Brain Imaging in Awake Animals

    Page(s): 446 - 453
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    In this paper we present a fully self-contained imaging instrument (30 mm overall length) that is capable of recording high speed and detect relatively small fluorescent signals (0.1% ΔF/F) from brain tissues potentially containing genetically-encoded sensors or dyes. This device potentially enables the study of neuronal activity in awake and mobile animals during natural behaviors without the stress and suppression of anesthesia and restraint. The device is a fully self-contained illumination system, wide field fluorescence microscope ( ~ 4.8mm2 FOV-25 um lateral resolution-1.8 × magnification-0.39 NA) and CMOS image sensor (32 × 32). The total weight of the system is 10 g and is capable of imaging up to 900 fps. We present voltage dye RH1692 experiments using the system to study the somatosensory cortex of mice during whisker movements using an air puff. View full abstract»

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  • An Analog Integrated Circuit Beamformer for High-Frequency Medical Ultrasound Imaging

    Page(s): 454 - 467
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    We designed and fabricated a dynamic receive beamformer integrated circuit (IC) in 0.35-μm CMOS technology. This beamformer IC is suitable for integration with an annular array transducer for high-frequency (30-50 MHz) intravascular ultrasound (IVUS) imaging. The beamformer IC consists of receive preamplifiers, an analog dynamic delay-and-sum beamformer, and buffers for 8 receive channels. To form an analog dynamic delay line we designed an analog delay cell based on the current-mode first-order all-pass filter topology, as the basic building block. To increase the bandwidth of the delay cell, we explored an enhancement technique on the current mirrors. This technique improved the overall bandwidth of the delay line by a factor of 6. Each delay cell consumes 2.1-mW of power and is capable of generating a tunable time delay between 1.75 ns to 2.5 ns. We successfully integrated the fabricated beamformer IC with an 8-element annular array. Experimental test results demonstrated the desired buffering, preamplification and delaying capabilities of the beamformer. View full abstract»

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  • 16-Channel CMOS Impedance Spectroscopy DNA Analyzer With Dual-Slope Multiplying ADCs

    Page(s): 468 - 478
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    We present a 16-channel, mixed-signal CMOS DNA analyzer that utilizes frequency response analysis (FRA) to extract the real and imaginary impedance components of the biosensor. Two computationally intensive operations, the multiplication and integration required by the FRA algorithm, are performed by an in-channel dual-slope multiplying ADC in the mixed-signal domain resulting in minimal area and power consumption. Multiplication of the input current by a digital coefficient is implemented by modulating the counter-controlled duration of the charging phase of the ADC. Integration is implemented by accumulating output digital bits in the ADC counter over multiple input samples. The 1.05 × 1.6 mm prototype fabricated in a 0.13 μm standard CMOS technology has been validated in prostate cancer DNA detection. Each channel occupies an area of only 0.06 mm2 and consumes 42 μW of power from a 1.2 V supply. View full abstract»

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  • New Approaches for Carbon Nanotubes-Based Biosensors and Their Application to Cell Culture Monitoring

    Page(s): 479 - 485
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    Amperometric biosensors are complex systems and they require a combination of technologies for their development. The aim of the present work is to propose a new approach in order to develop nanostructured biosensors for the real-time detection of multiple metabolites in cell culture flasks. The fabrication of five Au working electrodes onto silicon substrate is achieved with CMOS compatible microtechnology. Each working electrode presents an area of 0.25 mm2, so structuration with carbon nanotubes and specific functionalization are carried out by using spotting technology, originally developed for microarrays and DNA printing. The electrodes are characterized by cyclic voltammetry and compared with commercially available screen-printed electrodes. Measurements are carried out under flow conditions, so a simple fluidic system is developed to guarantee a continuous flow next to the electrodes. The working electrodes are functionalized with different enzymes and calibrated for the real-time detection of glucose, lactate, and glutamate. Finally, some tests are performed on surnatant conditioned medium sampled from neuroblastoma cells (NG-108 cell line) to detect glucose and lactate concentration after 72 hours of cultivation. The developed biosensor for real-time and online detection of multiple metabolites shows very promising results towards circuits and systems for cell culture monitoring. View full abstract»

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  • A {0.35}~\mu{\rm m} Sub-ns Wake-up Time ON-OFF Switchable LVDS Driver-Receiver Chip I/O Pad Pair for Rate-Dependent Power Saving in AER Bit-Serial Links

    Page(s): 486 - 497
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    This paper presents a low power switchable current mode driver/receiver I/O pair for high speed serial transmission of asynchronous address event representation (AER) information. The sparse nature of AER packets (also called events) allows driver/receiver bias currents to be switched off to save power. The on/off times must be lower than the bit time to minimize the latency introduced by the switching mechanism. Using this technique, the link power consumption can be scaled down with the event rate without compromising the maximum system throughput. The proposed technique has been implemented on a typical push/pull low voltage differential signaling (LVDS) circuit, but it can easily be extended to other widely used current mode standards, such as current mode logic (CML) or low-voltage positive emitter-coupled logic (LVPECL). A proof of concept prototype has been fabricated in 0.35 μm CMOS incorporating the proposed driver/receiver pair along with a previously reported switchable serializer/deserializer scheme. At a 500 Mbps bit rate, the maximum event rate is 11 Mevent/s for 32-bit events. In this situation, current consumption is 7.5 mA and 9.6 mA for the driver and receiver, respectively, while differential voltage amplitude is ±300 mV. However, if event rate is lower than 20-30 Kevent/s, current consumption has a floor of 270 μA for the driver and 570 μA for the receiver. The measured ON/OFF switching times are in the order of 1 ns. The serial link could be operated at up to 710 Mbps bit rate, resulting in a maximum 32-bit event rate of 15 Mevent/s . This is the same peak event rate as that obtained with the same SerDes circuits and a non-switched driver/receiver pair. View full abstract»

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  • Multichannel Bipotentiostat Integrated With a Microfluidic Platform for Electrochemical Real-Time Monitoring of Cell Cultures

    Page(s): 498 - 507
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    An electrochemical detection system specifically designed for multi-parameter real-time monitoring of stem cell culturing/differentiation in a microfluidic system is presented. It is composed of a very compact 24-channel electronic board, compatible with arrays of microelectrodes and coupled to a microfluidic cell culture system. A versatile data acquisition software enables performing amperometry, cyclic voltammetry and impedance spectroscopy in each of the 12 independent chambers over a 100 kHz bandwidth with current resolution down to 5 pA for 100 ms measuring time. The design of the platform, its realization and experimental characterization are reported, with emphasis on the analysis of impact of input capacitance (i.e., microelectrode size) and microfluidic pump operation on current noise. Programmable sequences of successive injections of analytes (ferricyanide and dopamine) and rinsing buffer solution as well as the impedimetric continuous tracking for seven days of the proliferation of a colony of PC12 cells are successfully demonstrated. View full abstract»

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  • A 0.09 \mu W Low Power Front-End Biopotential Amplifier for Biosignal Recording

    Page(s): 508 - 516
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    This work presents a biopotential front-end amplifier in which the MOS transistors are biased in subthreshold region with a supply voltage and current of 0.4-0.8 V and 0.23-1.86 μA, respectively, to reduce the system power. Flicker noise is then removed using a chopping technique, and differential interference produced by electrode impedance imbalance is suppressed using a Gm-C filter. Additionally, the circuit is fabricated using TSMC 0.18 μm CMOS technology with a core area of 0.77 × 0.36 mm2. With a minimum supply voltage of 0.4 V, the measured SNR and power consumption of the proposed IC chip are 54.1 dB and 0.09 μW , respectively. View full abstract»

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  • Special Issue: Omics Based Companion Diagnostics for Personalized Medicine

    Page(s): 517
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  • Open Access [advertisement]

    Page(s): 518
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    Page(s): 519
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  • IEEE Transactions on Biomedical Circuits and Systems information for authors

    Page(s): C4
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  • IEEE Transactions on Biomedical Circuits and Systems society information

    Page(s): C3
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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