Jerald Yoo

The Human Body Characteristics as a Signal Transmission Medium for Intrabody Communication

The human body characteristics as a signal transmission medium are studied for the application to intrabody communication. The measurements of the body channel cover the frequency range from 100 kHz to 150 MHz and the distance on the body up to 1.2 m. A distributed RC model is developed to analyze the large variation of the channel properties according to the frequency and channel length. The simulation results using the channel model match well with the measurements in both the frequency and time domains. The effect of the ground plane to the body channel transceivers is also investigated and an empirical formula for the minimum ground size is obtained. Finally, the amount of the electromagnetic radiation due to the body antenna effect is measured. With regards to the Federal Communications Commission regulations, the proper frequency range for the intrabody communication is determined to satisfy given bit error rate requirements

A 5.2 mW Self-Configured Wearable Body Sensor Network Controller and a 12

A self-configured body sensor network controller and a high efficiency wirelessly powered sensor are presented for a wearable, continuous health monitoring system. The sensor chip harvests its power from the surrounding health monitoring band using an Adaptive Threshold Rectifier (ATR) with 54.9% efficiency, and it consumes 12 μW to implement an electrocardiogram (ECG) analog front-end and an ADC. The ATR is implemented with a standard CMOS process for low cost. The adhesive bandage type sensor patch is composed of the sensor chip, a Planar-Fashionable Circuit Board (P-FCB) inductor, and a pair of dry P-FCB electrodes. The dry P-FCB electrodes enable long term monitoring without skin irritation. The network controller automatically locates the sensor position, configures the sensor type (self-configuration), wirelessly provides power to the configured sensors, and transacts data with only the selected sensors while dissipating 5.2 mW at a single 1.8 V supply. Both the sensor and the health monitoring band are implemented using P-FCB for enhanced wearability and for lower production cost. The sensor chip and the network controller chip occupy 4.8 mm2 and 15.0 mm2, respectively, including pads, in standard 0.18 μm 1P6M CMOS technology.

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A wearable electrocardiogram (ECG) acquisition system implemented with planar-fashionable circuit board (P-FCB)-based shirt is presented. The proposed system removes cumbersome wires from conventional Holter monitor system for convenience. Dry electrodes screen-printed directly on fabric enables long-term monitoring without skin irritation. The ECG monitoring shirt exploits a monitoring chip with a group of electrodes around the body, and both the electrodes and the interconnection are implemented using P-FCB to enhance wearability and to lower production cost. The characteristics of P-FCB electrode are shown, and the prototype hardware is implemented to successfully verify the proposed concept.

W Wirelessly Powered Sensor for a Continuous Health Monitoring System

Recently, several attempts have been made to continuously monitor chronic diseases in everyday life, but their large form factors or battery power limitations still remain to be solved. Security and/or requirements of interference resilience are stringent for health monitoring, and therefore, using an open-air wireless ISM band [1] is not suitable for a health monitoring body sensor network (BSN). This paper presents a self-configured wearable BSN system with high efficiency wirelessly powered sensors that continuously monitor ECG and other vital signals at the selected locations on the body with low power consumption.

A Wearable ECG Acquisition System With Compact Planar-Fashionable Circuit Board-Based Shirt

A battery-powered wideband pulse transceiver with a direct-coupled interface is presented for human-body communications. The optimum channel bandwidth of 10kHz to 100MHz is identified as the bodywire channel. The transceiver based on all-digital CDR circuit with quadratic sampling technique has 2Mb/s data rate at a BER of 10-7. The 0.25mum CMOS transceiver occupies 0.85mm2 and consumes less than 0.2mW from a 1V supply

A 5.2mW self-configured wearable body sensor network controller and a 12µW 54.9% efficiency wirelessly powered sensor for continuous health monitoring system

A wirelessly powered patch-type healthcare sensor IC is presented for a wearable body sensor network (W-BSN) to continuously monitor personal vital signals. Thick-film electrodes are screen printed on a fabric by planar-fashionable circuit board (P-FCB) technology on which stainless steel powder with a grain size of 100 μ m is added to reduce both contact impedance as well as motion artifacts. A nested chopped amplifier (NCA) is designed and optimized for the proposed patch-type healthcare sensor with a reduced electrode referred noise of 0.5 μVrms. A programmable gain and bandwidth amplifier (PGA) stage is also implemented to accommodate various dynamic ranges of vital signals. A 10-b folded successive approximation register (SAR) analog-to-digital converter (ADC) reduces capacitive digital-to-analog conversion size by 94% and relaxes the power budget of the ADC driver by 36%. Measured sensor resolution is 9.2 b and rejects common-mode interference larger than 100 dB while consuming only 12 μ W of power supplied wirelessly. A 2.0 mm × 1.3 mm sensor IC is fabricated in 0.18-μm 1P6M CMOS technology. The chip is directly integrated between two screen printed electrodes and stacked by a screen printed fabric inductor. With the proposed patch-type sensor, personal healthcare without expensive batteries is possible in W-BSN and greatly improves wearability and convenience in use.

A 2Mb/s Wideband Pulse Transceiver with Direct-Coupled Interface for Human Body Communications

An energy-efficient scalable PHY transceiver for body-coupled communications is presented. The analog front-end exploits pulse detection and cross-delayed sampling techniques. The digital baseband has a hierarchical block gating architecture for energy-efficient packet processing. The 0.18mum CMOS PHY transceiver chip operates up to 10Mb/s while consuming 2.6mW from a 0.9V supply

A 0.5-

A near-field coupling transceiver integrated with a fault-tolerant network switch is implemented for inter-layer and intra-layer wearable body area network. The inductive coupling transceiver employs a resonance compensator (RC) with a digitally controlled on-chip capacitor bank and a variable hysteresis Schmitt trigger to compensate dynamic and static variances of woven inductor, and it enables 10 Mbps wireless transaction with the reception energy of 1.12 pJ/b at 2.5 V supply. The network switch introduces new fault-tolerant protocol to eliminate the routing table and reduces power consumption by 70% compared with the conventional switch using torus topology. The transceiver with the switch and the RC are implemented in 0.25-mum 1P5M CMOS process technology, occupying 2.0 mm2 and 0.8 mm2 area, respectively.

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A body sensor network using human body as a communication medium is analyzed and designed to achieve both power-and energy-efficiency. An analysis of the body channel network on frequency, distance, transmitting power and received power is performed. The analysis reveals the star topology consumes less energy than the ad-hoc topology for body channel network. Based on the analysis results, the packet structure for body channel network, with variable payload size that minimizes energy consumption, is designed.

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An attachable ECG sensor adhesive bandage is implemented for continuous ECG monitoring system by using Planar-Fashionable Circuit Board (P-FCB) technology. The sensor patch improves convenience at low cost: it is composed of dry electrodes and an inductor directly screen printed on fabric, and the sensor chip is also directly wire bonded on fabric. The sensor patch is wirelessly powered to remove battery for safety. Dry electrodes minimize skin irritation to enable long term monitoring. The implemented sensor patch successfully demonstrates capturing of ECG signal while dissipating only 12uW power.