Hoi-Jun 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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An energy-efficient network-on-chip (NoC) is presented for possible application to high-performance system-on-chip (SoC) design. It incorporates heterogeneous intellectual properties (IPs) such as multiple RISCs and SRAMs, a reconfigurable logic array, an off-chip gateway, and a 1.6-GHz phase-locked loop (PLL). Its hierarchically-star-connected on-chip network provides the integrated IPs, which operate at different clock frequencies, with packet-switched serial-communication infrastructure. Various low-power techniques such as low-swing signaling, partially activated crossbar, serial link coding, and clock frequency scaling are devised, and applied to achieve the power-efficient on-chip communications. The 5 /spl times/5 mm/sup 2/ chip containing all the above features is fabricated by 0.18-/spl mu/m CMOS process and successfully measured and demonstrated on a system evaluation board where multimedia applications run. The fabricated chip can deliver 11.2-GB/s aggregated bandwidth at 1.6-GHz signaling frequency. The chip consumes 160 mW and the on-chip network dissipates less than 51 mW.

W Wirelessly Powered Sensor for a Continuous Health Monitoring System

The signal transmission mechanism on the surface of the human body is studied for the application to body channel communication (BCC). From Maxwells equations, the complete equation of electrical field on the human body is developed to obtain a general BCC model. The mechanism of BCC consists of three parts according to the operating frequencies and channel distances: the quasi-static near-field coupling part, the reactive induction-field radiation part, and the surface wave far-field propagation part. The general BCC model by means of the near-field and far-field approximation is developed to be valid in the frequency range from 100 kHz to 100 MHz and distance up to 1.3 m based on the measurements of the body channel characteristics. Finally, path loss characteristics of BCC are formulated for the design of BCC systems and many potential applications.

Low-power network-on-chip for high-performance SoC design

An RF-powered transponder with temperature and photo sensors is designed and fabricated for environmental monitoring. The transponder gathers power from external ISM (860-960MHz) band RF signal and senses ambient temperature and light. It contains a supply voltage generator, a temperature-compensated ring oscillator, an oversampling synchronizer, a PTAT temperature sensor and an abrupt transition buffered photo sensor. Its internal clock frequency has variation less than 7% for 1.5-V supply voltage and 90/spl deg/C temperature change. The transponder occupies 0.4mm/sup 2/ with 0.25-/spl mu/m CMOS process and dissipates only 5.14-/spl mu/W during active state.

The Signal Transmission Mechanism on the Surface of Human Body for Body Channel Communication

Fabrication methods of planar printed circuits on fabrics are introduced and their electrical characteristics are measured and analyzed. Wet patterning method like screen printing as well as dry process of sputtering are used to fabricate the patterned film electrodes on various types of fabrics. The minimum width of the patterns is 0.2 mm for screen printing and 0.1 mm for gold sputtering, and the typical sheet resistance is 134 m ¿/¿. Fabrication methods of capacitors of 1 pF-1 nF and inductors of 500 nH-1 ¿H at 10 MHz on the fabrics are also introduced. Bonding and packaging of silicon chip directly on the fabric circuit board are proposed and their mechanical properties are investigated. The ac impedance of the transmission line is measured as 201-215 ¿ with variation, and the time-domain reflectometry profile shows that the -3 dB frequency of the printed transmission line of 15 cm on the fabric is 80 MHz. A complete system composed of a fabric capacitor sensor input, a controller system-on-a-chip, and an LED array display is implemented on the fabric and its operation is demonstrated successfully.

A 5.1-/spl mu/W UHF RFID tag chip integrated with sensors for wireless environmental monitoring

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.

Electrical Characterization of Screen-Printed Circuits on the Fabric

An ECG signal processing method with quad level vector (QLV) is proposed for the ECG holter system. The ECG processing consists of the compression flow and the classification flow, and the QLV is proposed for both flows to achieve better performance with low-computation complexity. The compression algorithm is performed by using ECG skeleton and the Huffman coding. Unit block size optimization, adaptive threshold adjustment, and 4-bit-wise Huffman coding methods are applied to reduce the processing cost while maintaining the signal quality. The heartbeat segmentation and the R-peak detection methods are employed for the classification algorithm. The performance is evaluated by using the Massachusetts Institute of Technology-Bostons Beth Israel Hospital Arrhythmia Database, and the noise robust test is also performed for the reliability of the algorithm. Its average compression ratio is 16.9:1 with 0.641% percentage root mean square difference value and the encoding rate is 6.4 kbps. The accuracy performance of the R-peak detection is 100% without noise and 95.63% at the worst case with -10-dB SNR noise. The overall processing cost is reduced by 45.3% with the proposed compression techniques.

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

A 201.4 GOPS real-time multi-object recognition processor is presented with a three-stage pipelined architecture. Visual perception based multi-object recognition algorithm is applied to give multiple attentions to multiple objects in the input image. For human-like multi-object perception, a neural perception engine is proposed with biologically inspired neural networks and fuzzy logic circuits. In the proposed hardware architecture, three recognition tasks (visual perception, descriptor generation, and object decision) are directly mapped to the neural perception engine, 16 SIMD processors including 128 processing elements, and decision processor, respectively, and executed in the pipeline to maximize throughput of the object recognition. For efficient task pipelining, proposed task/power manager balances the execution times of the three stages based on intelligent workload estimations. In addition, a 118.4 GB/s multi-casting network-on-chip is proposed for communication architecture with incorporating overall 21 IP blocks. For low-power object recognition, workload-aware dynamic power management is performed in chip-level. The 49 mm2 chip is fabricated in a 0.13 ¿m 8-metal CMOS process and contains 3.7 M gates and 396 KB on-chip SRAM. It achieves 60 frame/sec multi-object recognition up to 10 different objects for VGA (640 × 480) video input while dissipating 496 mW at 1.2 V. The obtained 8.2 mJ/frame energy efficiency is 3.2 times higher than the state-of-the-art recognition processor.

ECG Signal Compression and Classification Algorithm With Quad Level Vector for ECG Holter System

This paper presents a low-power wideband signaling (WBS) digital transceiver for data transmission through a human body for body area network applications. The low-power and highspeed human body communication (HBC) utilizes a digital transceiver chip based on WBS and adopts a direct-coupled interface (DCI) which uses an electrode of 50-Omega impedance. The channel investigation with the DCI identities an optimum channel bandwidth of 10 kHz to 100 MHz. The WBS digital transceiver exploits a direct digital transmitter and an all-digital clock and data recovery (CDR) circuit. To further reduce power consumption, the proposed CDR circuit incorporates a low-voltage digitally-controlled oscillator and a quadratic sampling technique. The WBS digital transceiver chip with a 0.25-mum standard CMOS technology has 2-Mb/s data rate at a bit error rate of 1.1 times 10-7, dissipating only 0.2 mW from a 1-V supply generated by a 1.5-V battery.