Jean-Michel Redouté

A survey on signals and systems in ambulatory blood pressure monitoring using pulse transit time

Blood pressure monitoring based on pulse transit or arrival time has been the focus of much research in order to design ambulatory blood pressure monitors. The accuracy of these monitors is limited by several challenges, such as acquisition and processing of physiological signals as well as changes in vascular tone and the pre-ejection period. In this work, a literature survey covering recent developments is presented in order to identify gaps in the literature. The findings of the literature are classified according to three aspects. These are the calibration of pulse transit/arrival times to blood pressure, acquisition and processing of physiological signals and finally, the design of fully integrated blood pressure measurement systems. Alternative technologies as well as locations for the measurement of the pulse wave signal should be investigated in order to improve the accuracy during calibration. Furthermore, the integration and validation of monitoring systems needs to be improved in current ambulatory blood pressure monitors.

An EMI Resisting LIN Driver in 0.35-micron High-Voltage CMOS

This paper describes the design of a local interconnect network (LIN) integrated output driver circuit exhibiting a high degree of immunity against conducted electromagnetic interference (EMI). The transmitted signal of this driver is shaped with a predefined slope so as to reduce electromagnetic emission at higher frequencies. The effect of EMI coupling from the data bus into the driver circuit is countered using a new feedback scheme which shields the slope shaping function from the output stage. Although the output signal may be heavily corrupted by EMI, the LIN driver continues to deliver an unaltered duty cycle, which is mandatory to obtain an error-free data transmission. Measurements show that this driver circuit manages to withstand the highest levels of the direct power injection (DPI) measurements independently of the injected EMI level.

EMI-Resistant CMOS Differential Input Stages

This paper studies and compares the performances of CMOS differential input stages with a high degree of immunity against electromagnetic interferences (EMIs) and introduces a source-buffered differential pair which is very resistant to EMI coupled at its inputs. The EMI behavior of this source-buffered differential-pair topology has been evaluated with a test chip: When injecting an EMI signal of 750 mV rms at the input terminals, the measured maximal EMI-induced input offset voltage corresponds to 116 mV for the source-buffered topology compared with 610 mV for the classic differential pair, which constitutes a major improvement.

Kuijk Bandgap Voltage Reference With High Immunity to EMI

This brief evaluates the effect of conducted electromagnetic interference (EMI) that is injected in the power supply of a classic Kuijk bandgap reference voltage circuit. Two modified Kuijk bandgap topologies with high immunity to EMI are introduced and compared to the original structure. Measurements of a test IC confirm the theoretical analyses.

Propagation, Power Absorption, and Temperature Analysis of UWB Wireless Capsule Endoscopy Devices Operating in the Human Body

With the increasing use of wireless capsule endoscopy (WCE) devices in healthcare, it is of utmost importance to analyze the electromagnetic power absorption and thermal effects caused by in-body propagation of wireless signals from these devices. This paper studies the path loss, specific absorption rate (SAR), specific absorption (SA), and temperature variation of the human body caused by an impulse-radio ultra-wideband (UWB) based WCE operating inside the human abdomen. In addition, the design and in-body performance of an UWB antenna with dimensions of 11.85×9×1.27 mm and operating from 3.5 to 4.5 GHz is described in this paper. Path loss is evaluated using both experimental and simulation based methods to characterize the in-body propagation channel. The experimental setup uses a pigs abdominal tissue samples to demonstrate the propagation characteristics of human tissue while a voxel model of the human body consisting of human tissue simulating materials is used in the simulations. The tissue properties, such as relative permittivity, are characterized according to the incident signal frequency and age of the tissue sample during simulations. The SAR and SA variations for different positions of the WCE device inside the colon and the small intestine of the human body model are analyzed using the finite integration technique as the discretization model. The dependency of the electromagnetic effects on the antenna positioning is investigated by using different positions of the antenna inside the human body.

A Biosafety Comparison Between Capacitive and Inductive Coupling in Biomedical Implants

This letter investigates the link efficiencies and ensuing biohazards when capacitive versus inductive coupling is used to power biomedical implants electromagnetically. Electromagnetic simulations illustrate that the power link efficiency of capacitive coupling decays slower as a function of the distance between plates compared to inductive coupling. Specifically, the case designs show that, using a transmitted power of 1 W at 5 MHz, capacitive coupling produces a 10-g averaged SAR value of 1.63 W/kg compared to 2.39 W/kg for an inductive coupling of the same dimension.

Classic and quantum capacitances in Bernal bilayer and trilayer graphene field effect transistor

Our focus in this study is on characterizing the capacitance voltage (C-V) behavior of Bernal stacking bilayer graphene (BG) and trilayer graphene (TG) as the channel of FET devices. The analyticalmodels of quantumcapacitance (QC) of BGand TGare presented. Although QC is smaller than the classic capacitance in conventional devices, its contribution to the total metal oxide semiconductor capacitor in graphene-based FET devices becomes significant in the nanoscale. Our calculation shows thatQCincreases with gate voltage in both BGand TGand decreases with temperaturewith some fluctuations.However, in bilayer graphene the fluctuation is higher due to its tunable band structure with external electric fields. In similar temperature and size, QC in metal oxide BG is higher thanmetal oxide TGconfiguration.Moreover, in both BGand TG, total capacitance ismore affected by classic capacitance as the distance between gate electrode and channel increases.However, QC ismore dominant when the channel becomes thinner into the nanoscale, and therefore wemostly deal with quantumcapacitance in top gate in contrast with bottomgate that the classic capacitance is dominant.

Design of a Miniaturized Wireless Blood Pressure Sensing Interface Using Capacitive Coupling

This paper presents the implementation of a miniaturized wireless blood pressure sensor interface. The system uses capacitive coupling in order to transmit the data, as well as wireless inductive powering. Designed for a bit length of 6.4 μs, the average power consumption of the device has been measured to be 20.5 μW and 2.85 mW in air and phantom material, respectively. The miniaturized sensor interface circuit consists of two plates with a diameter of 2.5 cm, which are connected by means of a thin wire; the devices maximum thickness is 5 mm.

A low-power wearable dual-band wireless body area network system: Development and experimental evaluation

Wireless body area network (WBAN) applications benefit extensively from the advantages offered by unique features of ultra-wideband (UWB) wireless communication, such as high data rate, low power consumption, and simple transmitter design. A major disadvantage in using UWB for WBAN applications is the complexities introduced by UWB receivers, such as high power consumption, poor receiver performance due to low sensitivity, and complex hardware implementation. This paper presents hardware implementation of a new communication system, where UWB is used for high data-rate transmission from sensor nodes and a 433-MHz industrial, scientific, and medical (ISM) band receiver is used for receiving low data-rate control messages at the sensor nodes. A full network system for WBAN applications has been implemented including a unique medium access control protocol. The proposed WBAN system is designed to dynamically control the pulses per bit value used for the UWB data communication using control messages received via the narrowband feedback link (i.e., the 433-MHz ISM link). This leads to dynamic bit error rate (BER) and power control at the sensor nodes, which improves the reliability of communication and power efficiency of sensor nodes under dynamic channel conditions. The performance of the system is evaluated in terms of BER, sensor initialization delay, and power consumption. This novel dual-band architecture utilizes the unique advantages offered by UWB communication and narrowband technology to enable high data rate, low-complexity hardware design, low power consumption, and small form factor for WBAN sensor systems.

Development of low-power UWB body sensors

Ultra-wide band (UWB) is gaining popularity as a physical layer technique for low power and high data rate wireless applications. Currently most wireless body area network (WBAN) platforms are based on narrowband wireless technology such as ZigBee and Bluetooth. This paper presents hardware implementation of impulse radio ultra-wide band (IR-UWB) based sensor nodes. Two major approaches for the development of an IR-UWB sensor node are discussed herein. A UWB receiver implementation using off-the-shelf components is also described. This communication system is used to evaluate the performance of the UWB sensor nodes in terms of bit error rate (BER). A technique for dynamically varying the pulse repetitive frequency (PRF) of the UWB pulses is also discussed in this paper as a further improvement for the suggested sensor designs.