Yongsang Kim

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.

\mu

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.

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.

Electrical Characterization of Screen-Printed Circuits on the Fabric

A low cost quadratic level compression algorithm is proposed for body sensor network system. The proposed algorithm reduces the encoding delay and the hardware cost, while maintaining the reconstructed signal quality. The quadratic compression level determined by the mean deviation value is used to preserve the critical information with high compression ratio. The overall CR is 8.4:1, the PRD is 0.897% and the encoding rate is 6.4Mbps. The 16-bit sensor node processor is designed, which supports the proposed compression algorithm. The processor consumes 0.56nJ/bit at 1V supply voltage with 1MHz operating frequency in 0.25-μm CMOS process.

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 method to fabricate circuits on the cloth, planar fashionable circuit board (P-FCB), is proposed. And its applications such as fabric passive elements, user I/O interface, and the fabric package are introduced. The electrical and the mechanical characteristic analysis of P-FCB and the system integration methodology establishment improve the system performance and productivity. A complete wearable system is implemented by P-FCB technology for the continuous sweat monitoring and the RFID tag antenna applications.

A low cost quadratic level ECG compression algorithm and its hardware optimization for body sensor network system

A planar thin-film technology is applied directly on the fabric to fabricate a planar fashionable circuit board (P-FCB) and to introduce a direct chip-integration technique on a P-FCB. Planar technology, which has helped make the current advance of electronics technology possible, is used to fabricate P-FCBs. Planar capacitor humidity sensors, a low-power controller chip and LEDs are integrated on a P-FCB for continuous healthcare monitoring applications. The P-FCB has the same electrical and mechanical properties as the clothes and also shows a graceful degradation in performance, exactly the same way as clothes do with time and usage.

A Wearable Fabric Computer by Planar-Fashionable Circuit Board Technique

A low energy sensor node processor is proposed for continuous healthcare monitoring application. The bio signal processing block is integrated into the processor to support the compression and the encryption. A quadratic level bio signal compression algorithm is proposed to reduce the transmission power consumption and the memory capacity. And the AES-128 data encryption datapath is integrated for user privacy and authentication. The CR is 8.4:1, the PRD is 0.897% and the compression rate is 6.4 Mbps. The encryption rate is 1.6 Mbps and the normalized performance is 0.4b/cycle/k-gates which is the highest value compared to the related works. The proposed processor consumes 0.56 nJ/bit at 1V supply voltage with 1MHz operating frequency in 0.25-mum CMOS process.

A 1.12mW Continuous Healthcare Monitor Chip Integrated on a Planar Fashionable Circuit Board

A low energy modulo-multiplier is proposed for elliptic curve cryptography (ECC) processor, especially for authentication in mobile device or key encryption in embedded health-care system. The multiplier uses only two 40-bit multipliers to execute 160-bit operation based on the Montgomery modulo-multiplication algorithm. Partial products of multiplication are accumulated with shift registers to get final 160-bit MSB of output value. One modulo-multiplication is executed with 20 clock cycles at 40 MHz operating frequency. It consumes 6.3 nJ for each modulo-multiplication at IV supply voltage. It is implemented by using 0.18-mum CMOS process and has 0.7 mm x 1.0 mm area.