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Biomedical Engineering, IEEE Transactions on

Issue 2 • Date March 1977

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Displaying Results 1 - 25 of 28
  • Instrumentation for Measuring Respiratory Impedance by Forced Oscillations

    Publication Year: 1977 , Page(s): 89 - 93
    Cited by:  Papers (13)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (977 KB)  

    Recent reports have suggested that the frequency dependence of the respiratory impedance may provide a sensitive method for characterizing early changes in pulmonary mechanics. A modification of the forced-oscillation technique provides an experimental method for obtaining the necessary data. A loudspeaker was used to provide the pressure oscillations, and the magnitudes and phase angle of the transduced pressure and flow signals were measured with a special electronics unit. A test comparing predicted values of a standard impedance (a 5-g bottle) to experimental data indicates that the measured amplitude is within 10 percent and the measured phase within over the frequency range of 1-16 Hz. Dog studies showed that measurements at all frequencies up to 16 Hz were reproducible within a few percent of the mean value on a given animal. Data obtained following bronchoconstriction and its reversal in six dogs indicate that the measurements are sensitive to alterations in pulmonary mechanics. Data from two dog models of clinical disease suggest that the technique may provide meaningful diagnostic information. View full abstract»

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  • System for Computing Montevideo Units for Monitoring Progress of Labor

    Publication Year: 1977 , Page(s): 94 - 101
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1582 KB)  

    Computation of uterine activity during labor from analog data is described. Uterine activity is measured in Montevideo units which are computed from the time record of intrauterine pressure. The objective of this paper is to describe the computation algorithms necessary to process an analog data record of intrauterine pressure to obtain Montevideo units. The analog data record contains unavoidable artifacts from patient motion, uterine elevation changes, plugged pressure tubes, and other extraneous sources. Algorithms are described that correct for artifacts, provide statistical smoothing, compute the first derivative, locate the maximum pressure of each contraction, and compute the intercontraction time interval. View full abstract»

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  • A Staged, Tortuous Microcapillary System: Hemodialysis and Ultrafiltration

    Publication Year: 1977 , Page(s): 102 - 106
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1005 KB)  

    A microcapillary system has been constructed by etching staged, tortuous microchannels onto stainless steel sheets; a flat membrane over the channel completes the microcapillary. The microcapillaries are sinusoidal and terminate every ¿¿to form a region where the output of all capillaries mix. There are three stages per centimeter. Tortuosity and staging greatly reduce boundary layers and increase mass transfer through the membrane. There are 430 000 capillaries per square meter of membrane. The capillaries are oval (125 ¿m X 250¿m); thus membrane area per unit volume is only 36 percent less than a hollow-fiber capillary. Initial testing indicates satisfactory clearances and hydraulic conductivities for Cuprophane PT-150 membrane. This microcapillary system should find many industrial and biomedical applications where prime volume per unit membrane area and concentration polarization are major concerns of design. View full abstract»

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  • A New Noninvasive Technique for Cardiac Pressure Measurement: Resonant Scattering of Ultrasound from Bubbles

    Publication Year: 1977 , Page(s): 107 - 110
    Cited by:  Papers (24)  |  Patents (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (834 KB)  

    We suggest and analyze a new technique for making non-invasive cardiac measurements. The technique involves measurement of the spectrum of ultrasound scattered from small bubbles injected into the circulatory system as they pass through the heart. We show that the resonant frequency observed in these spectra will vary as the cardiac pressure changes. Thus the variations of the resonance can be calibrated to give the pressure excursions in a cardiac chamber. Preliminary bench tests of the method are described which show the predicted shift with pressure of the resonance frequency of bubbles in water. View full abstract»

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  • An Organ Cryopreservation Apparatus

    Publication Year: 1977 , Page(s): 111 - 115
    Cited by:  Patents (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1789 KB)  

    Hardware necessary for cryopreservation of the isolated rat heart is described, consisting of a perfusion system and a temperature controller. The controller automatically impresses a linear temperature-time profile on the organ system with a temperature range of +40°C to -40°C. It is of the analog feedback type and features both rate and proportional feedback. Maximum temperature rate of change is ±8°C/min with this system and long term stability is ±0.5°C over 24 h. Biological applications of this device are discussed. View full abstract»

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  • Normalization of Insulin Delivery to Diabetics by Pulsed Insulin Infusion

    Publication Year: 1977 , Page(s): 116 - 121
    Cited by:  Papers (4)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2313 KB)  

    The objective was to continuously provide insulin to diabetic patients so as to mimic the time course of natural plasma insulin in response to meal ingestion in normal subjects. The normal curve of plasma insulin was well approximated as a double exponential, and this function was used as the output of a mathematical model of the body compartment plasma insulin-clearance system in order to derive an input expression. This input expression was thus the infusion time function needed to produce the desired plasma time function of insulin concentration in diabetics. The infusion function was implemented with a special purpose computer, designed with logic technics, that was then used to drive a servo infusion pump. The system delivered a 4-5-h pulse of insulin, the parameters of which were tailored for each patient's body weight and clearance rate, and with the different required profile for each of the three daily meals. These pulses rode on top of a constant basal infusion rate, the basal rate being delivered only throughout the night hours. The system was successfully tested on a simulated (hydraulic) patient, and then on one of us as a human volunteer., It has since been used with 10 diabetic patients in which the original objective was accomplished with satisfactory clinical results. View full abstract»

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  • Parylene as a Chronically Stable, Reproducible Microelectrode Insulator

    Publication Year: 1977 , Page(s): 121 - 128
    Cited by:  Papers (91)  |  Patents (38)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3971 KB)  

    One of the major problems in the design of neurophysiologiv extracellular microelectrodes is the application and selective removal of the insulation. In addition to the usual problems of achieving pin-hole-free coatings and reproducible tip exposures and impedances, chronic electrode designshave the additional requirement of maintaining megohm levels of electrical isolation for months in vivo. A method of insulating finely tapered microelectrodes with complicated shapes by vapor condensation of Parylene-C is presented, along with a method for exposing controlled, reproducible lengths of their tips. In vivo and in vitro impedance tests and unit records obtained over 100 days in monkey motor cortex are presented. The electric arc process used to expose Parylene-covered iridium and tungsten microelectrodes is found to give cleaner recording surfaces with impedances lower than those obtainable with previously described methods. Chronic iridium microelectrodes so fabricated have recorded unit potentials and maintained constant impedances for over 4 months in vivo. View full abstract»

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  • Capacitive Modulation of Micropipet Impedance

    Publication Year: 1977 , Page(s): 129 - 134
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (995 KB)  

    Quantitative theoretical and experimental evidence is presented suggesting that the saline-filled, glass micropipets employed in microvascular pressure measurements behave electrically as simple, parallel resistor-capacitor combinations in which the capacitance is dependent upon the length of the pipet in contact with the conductive fluid surrounding the tip. Changes in the apparent pipet impedance arising from modest alterations in the immersion length are sufficient to cause zero-level shifts in the measured pressure. View full abstract»

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  • Minimizing Electrode Motion Artifact by Skin Abrasion

    Publication Year: 1977 , Page(s): 134 - 139
    Cited by:  Papers (45)  |  Patents (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1173 KB)  

    Motion artifacts frequently cause erroneous results in biopotential measurement. When surface electrodes and conducting paste are used, a major cause of motion artifact is change in skin potential. The most effective means of minimizing this artifact is light abrasion of the sidn with fine sandpaper. A very mild paste is then required to avoid skin irritation. View full abstract»

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  • A No-Touch Ocular Pulse Measurement System for the Diagnosis of Carotid Occlusions

    Publication Year: 1977 , Page(s): 139 - 148
    Cited by:  Papers (6)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3362 KB)  

    The ocular pulse (OP) is the minute, radial displacement of the corneal surface caused by arterial pressure pulsations in the ocular circulation acting on the compliance of the cornea. Features of the OP waveform have been shown by several workers to be important diagnostic indicators of cerebrovascular disease (CVD) in which the common carotid and/or lower internal carotid arteries are significantly occluded. Early diagnosis of CVD is held to be important in predicting strokes and in implementing procedures to lower their likelihood. View full abstract»

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  • Computer Analysis of Spatial Integration in Vertebrate Retinal Horizontal Cells

    Publication Year: 1977 , Page(s): 149 - 152
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (765 KB)  

    A model is developed for the electrically coupled horizontal cells of the vertebrate retina. The model consists of a weighted distributed-parameter network in which the elements have direct cellular significance: transmembrane conductance and capacitance, and radial coupling resistance. Membrane polarization is viewed as a change in the overall membrane conductance in response to photoreceptor influence. Model simulation is implemented on a computer using a circuit analysis program. As a structural representation of the S-space, the model accurately spreads potential, but fails to integrate photoreceptor activity spatially like the S-space. It has been suggested that retinal scattering is the cause of this discrepancy, but the analysis here indicates that photoreceptor coupling is probably the major influence. View full abstract»

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  • Light Scattering Study on Motile Spermatozoa

    Publication Year: 1977 , Page(s): 153 - 157
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1929 KB)  

    The light scattering technique with a photoelectron counting method was applied to determine the speed distribution of spermatozoa, when a short measurement time and a weak illuminating light are prerequisite to avoid the effects of deterioration and light injury. The result is quantitatively in good agreement with the one obtained in other methods. It was found that the theory developed from the light scattering study of bacteria in artificial solution can be applied without modification to the light scattered from motile spermatozoa in semen containing various adulterations. Therefore, this technique proves to be useful in finding the accurate motility of spermatozoa in a very short observation time. View full abstract»

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  • Computerized Tomography Using Video Recorded Fluoroscopic Images

    Publication Year: 1977 , Page(s): 157 - 169
    Cited by:  Papers (17)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (7792 KB)  

    In this paper we investigate the possibility of constructing computerized tomograms using data collected from a fluoroscopic system. It is shown that through proper handling of these data, useful images can be obtained. The system offers the advantages of eliminating the need for a highly stabilized, linear translating mechanism, and also of requiring relatively low patient dosage. In addition, the data gathering can be done in essentially real time. View full abstract»

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  • Three-Dimensional Imaging of Multimillimeter Sized Cold Lesions by Focusing Collimator Coincidence Scanning (FCCS)

    Publication Year: 1977 , Page(s): 169 - 177
    Cited by:  Papers (3)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1874 KB)  

    A twin-probe high-resolution focusing collimator coincidence scanning system has been developed which can tomographically image multimillimeter structures. The three-dimensional detection and imaging capabilities, the related off-focal suppression, and the sensitivity are compared with standard techniques. View full abstract»

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  • A Pattern Classification System for the Identification of Irradiated Chromosomes

    Publication Year: 1977 , Page(s): 178 - 185
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1380 KB)  

    Monitoring health-related radiation damage is important for the future, and a system to detect chromosomal aberrations associated with radiation is extremely useful for monitoring populations exposed to radiation. In general, the most useful indicator of radiation damage at the cellular level is the occurrence of ring, dicentric, fragment, and fragment ring chromosomes. View full abstract»

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  • A Versatile Active Attenuator for Wide-Band and Narrow-Band Applications in Ultrasound Pulse-Echo Systems

    Publication Year: 1977 , Page(s): 186 - 187
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1575 KB)  

    An active calibrated attenuator which can be used with existing medical ultrasound pulse-echo systems is presented. Accurate signal attenuation over a 122-dB range is performed on signals of frequencies of up to 10 MHz. Wide-band or narrow-band operation is achieved with no insertion loss. The attenuator may also function as a preamplifier with up to 14.8-dB gain. View full abstract»

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  • Digital Electronic Control of Automatic Ventilators

    Publication Year: 1977 , Page(s): 188 - 190
    Cited by:  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (662 KB)  

    We have developed a digital system for use in ventilator control. The basic principle of this system is that every respiratory cycle is divided into a fixed number of counts. The control of the ratio of inspiration time to expiration time is accomplished by selecting a variable time out of the fixed time interval and designating it inspiration time. The remaining counts become expiration time. Respiratory rate is adjusted by varying the total time interval, and the ratio is adjusted by selecting a different inspiration time. The output of a digital-to-analog converter driven by the counters is adjustable and proportional to tidal volume. By inserting read only memories between the ratio scalars and the digital-to-analog converter input, a large number of different inspiration waveforms are generated. View full abstract»

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  • A Sample/Long-Term-Hold Digital Circuit for Physiological Signal Monitoring

    Publication Year: 1977 , Page(s): 190 - 191
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (475 KB)  

    An uncomplicated circuit to sample a signal and digitally store its value is given. A modification to store the maximum or minimum value attained by the signal is also presented. The drift for these circuits is small, and the input signal may be obtained in digital form. View full abstract»

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  • Description of 15-Channel Analog Selector

    Publication Year: 1977 , Page(s): 191 - 193
    Cited by:  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2964 KB)  

    A system for selecting a patient with cardiac arrhythmias in an intensive care setting and providing remote monitoring and consultation by a cardiologist is described. The system may have application where coronary units and other intensive care units axe widely separated geographically. View full abstract»

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  • A Transient Recorder/Digitizer for Biological Applications

    Publication Year: 1977 , Page(s): 193 - 195
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1778 KB)  

    A transient recorder with digitized output is described. Four consecutive time regions of an analog voltage signal can be sampled at different rates. A delayed-trigger output is included, which allows the option of triggering the transient subsequent to the starting of the recorder. The timing and control circuit for the recorder is discussed in detail. View full abstract»

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  • A Proposed Miniature Red/Infrared Oximeter Suitable for Mounting on a Catheter Tip

    Publication Year: 1977 , Page(s): 195 - 197
    Cited by:  Papers (4)  |  Patents (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (641 KB)  

    A miniature red/infrared oximeter has, been developed that is suitable for mounting on a catheter tip and does not use fiber-optics. Two light-emitting diodes (LED's) and a phototransistor are mounted on the catheter tip such that conversion between optical and electrical signals takes place right at the tip. In vitro calibration shows that the infrared-to-red reflectance ratio is essentially linearly dependent on oxygen saturation (OS). The calibration constants depend on hematocrit and on blood flow. View full abstract»

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  • Application of a Muscle-Potential Monitor to Electroconvulsive Therapy

    Publication Year: 1977 , Page(s): 197 - 199
    Cited by:  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (596 KB)  

    A battery-operated IC amplifier converts muscle potentials to audio signals. It has been successfully used clinically to monitor patients undergoing electroconvulsive therapy for evidence of muscle relaxation, duration, and bilaterality of response. View full abstract»

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  • An Event Counter with a Selectable Time Gate for Neurophysiological Applications

    Publication Year: 1977 , Page(s): 199 - 201
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1913 KB)  

    A low-cost TTL counter with a selectable time gate is described. A manual or an external trigger initiates the time-gated counting cycle. Included in the circuitry is a variable trigger delay and a test circuit that allows display of the clock signal. The counter has applications in neurophysiology including counting units for a predetermined time interval. View full abstract»

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  • A Primate-Restraint Device for Use in Microwave Biological Research

    Publication Year: 1977 , Page(s): 201 - 203
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3275 KB)  

    A restraint chair has been developed for use with subhuman primates in microwave biological research. The chair is essentially non-reflective, causing minimal perturbation of the field incident on the animal. The basic design of the device is simple and adaptable to different experimental configurations as required. Department. View full abstract»

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  • A Signal Simulator for Strain Gauge Type Pressure Transducer Amplifiers

    Publication Year: 1977 , Page(s): 203 - 204
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (307 KB)  

    A simulator circuit is presented which permits the introduction of external electrical signals mto both dc and carrier type strain gauge amplifiers. View full abstract»

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Aims & Scope

IEEE Transactions on Biomedical Engineering contains basic and applied papers dealing with biomedical engineering. Papers range from engineering development in methods and techniques with biomedical applications to experimental and clinical investigations with engineering contributions.

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Editor-in-Chief
Bin He
Department of Biomedical Engineering