Ho-Yin Lee

Wireless Body Sensor Network With Adaptive Low-Power Design for Biometrics and Healthcare Applications

A four-levels hierarchical wireless body sensor network (WBSN) system is designed for biometrics and healthcare applications. It also separates pathways for communication and control. In order to improve performance, a communication cycle is constructed for synchronizing the WBSN system with the pipeline. A low-power adaptive process is a necessity for long-time healthcare monitoring. It includes a data encoder and an adaptive power conserving algorithm within each sensor node along with an accurate control switch system for adaptive power control. The thermal sensor node consists of a micro control unit (MCU), a thermal bipolar junction transistor sensor, an analog-to-digital converter (ADC), a calibrator, a data encoder, a 2.4-GHz radio frequency transceiver, and an antenna. When detecting ten body temperature or 240 electrocardiogram (ECG) signals per second, the power consumption is either 106.3 ¿W or 220.4 ¿W. By switching circuits, multi sharing wireless protocol, and reducing transmission data by data encoder, it achieves a reduction of 99.573% or 99.164% in power consumption compared to those without using adaptive and encoding modules. Compared with published research reports and industrial works, the proposed method is 69.6% or 98% lower than the power consumption in thermal sensor nodes which consist only of a sensor and ADC (without MCU, 2.4-GHz transceiver, modulator, demodulator, and data encoder) or wireless ECG sensor nodes which selected Bluetooth, 2.4-GHz transceiver, and Zigbee as wireless protocols.

A Wireless Body Sensor Network System for Healthcare Monitoring Application

A four levels hierarchy wireless body sensor network (WBSN) is proposed for monitoring healthcare applications. It is separated into communication and control systems. In the communication system, the carrier frequency used in the human body is 402-405 MHz as medical implant communication systems (MICS) band by FCC and the coexistent wireless communication system (2.4 / 60 GHz) was used to transmit the merged biomedical data in the higher levels of the communication system. An adaptive low power and variable resolution control systems are designed into the control system. In order to improve the performance, a communication cycle is created for synchronizing the WBSN system with pipeline control. Each sensor node consists of a micro control unit (MCU), variable sample rate generator, sensor, ADC, data encoder, 402-405 MHz RF transceiver, and antenna. This paper presents a WBSN system, which not only gains the benefits of more flexible, easy development, run-time reconfigurable and variable resolution, but also significantly reduces considerable power consumptions with adaptive low power design.

A variable control system for wireless body sensor network

There is an increasing need to develop more flexible and intelligent low power wireless body sensor network (WBSN) system for healthcare monitoring applications. Technical advancements in micro-sensors, micro electro- mechanical system (MEMS) devices, low power electronics, and radio frequency (RF) circuits and systems have enabled both design and development of such highly integrated system. In this paper, we present a wireless body sensor network system with the capability of variable resolution function, which enables several resolutions for users selecting. The four levels hierarchical architecture is working well with communication system and control system. The accurate pipeline control will make implement variable resolution design in WBSN system easily and advance the performance efficiently. A variable sample rate generator is designed in each sensor node for producing different sample signals to ADC for variable resolutions. The SNR of ECG can be promoted from 25 dB to 73 dB when extraordinary situation of ECG occurs.

DESIGNING LOW POWER OF SIGMA DELTA MODULATOR FOR BIOMEDICAL APPLICATION

This paper discusses the design of micro power Sigma-delta modulator with oversampling technology. This Sigma-delta modulator design is paid special attention to its low power application of portable electronic system in digitizing biomedical signals such as Electro-cardiogram (ECG), Electroencephalogram (EEG) etc. [1]. A high performance, low power second order Sigma-delta modulator is more useful in analog signal acquisition system. Using Sigma-delta modulator can reduce the power consumption and cost in the whole system. The original biomedical signal can be reconstructed by simply applying the digital bit stream from the modulator output through a low-pass filter. The loop filter of this modulator has been implemented by using switch capacitor (SC) integrators and using simple circuitry consists of OpAmps, Comparator and DAC. In general, the resolution of modulator is about 10 bits for biomedical application. In this two order Sigma-delta modulator simulation results of the 1.8V sigma delta modulator show a 68 dB signal-to-noise-and-distortion ratio (SNDR) in 4 kHz biomedical signal bandwidth and a sampling frequency equal to 1 MHz in the 0.18 μ m CMOS technology. The power consumption is 400 μ W. It is very suitable for low power application of biomedical instrument design.

A CMOS Smart Thermal Sensor for Biomedical Application

This paper describes a smart thermal sensing chip with an integrated vertical bipolar transistor sensor, a Sigma Delta Modulator (SDM), a Micro-Control Unit (MCU), and a bandgap reference voltage generator for biomedical application by using 0.18μm CMOS process. The npn bipolar transistors with the Deep N-Well (DNW) instead of the pnp bipolar transistor is first adopted as the sensor for good isolation from substrate coupling noise. In addition to data compression, Micro-Control Unit (MCU) plays an important role for executing auto-calibration by digitally trimming the bipolar sensor in parallel to save power consumption and to reduce feedback complexity. It is different from the present analog feedback calibration technologies. Using one sensor, instead of two sensors, to create two differential signals in 180° phase difference input to SDM is also a novel design of this work. As a result, in the range of 0°C to 80°C or body temperature (37±5°C), the inaccuracy is less than ±0.1°C or ±0.05°C respectively with one-point calibration after packaging. The average power consumption is 268.4μW with 1.8V supply voltage.

Wireless sensor network system by separating control and data path (SCDP) for bio-medical applications

There is an increasing need to develop flexible, reconfigurable, and intelligent low power wireless sensor network (WSN) system for healthcare monitoring applications. Technical advancements in micro-sensors, micro electromechanical system (MEMS) devices, low power electronics, and radio frequency (RF) circuits and systems have enabled both design and development of such highly integrated system. In this paper, we present the wireless sensor network system, which is separated into control and data paths with different transmission frequencies. The control path sends the power and function control commands from computer to each sensor nodes by 2.4 GHz band. There are four levels in the WSN system. The data path transmits measured data from sensor layer to sensor group layer by 2.4 GHz, and transmits between sensor group, application and system layers by 60 GHz. This hierarchical architecture will make it possible to reconfigurable map application to WSN. The accurate pipeline control system will advance the performance efficiently, and the adaptive low power control system will reduce lots of power consumptions.

Low-Power 2.4-GHz Transceiver in Wireless Sensor Network for Bio-medical Applications

There is a low power wireless transceiver system for healthcare monitoring applications in wireless sensor network (WSN). Technical advancements in micro-sensors, micro electromechanical system (MEMS) devices, low-power electronics, and radio frequency (RF) circuits and systems have enabled both design and development of such highly integrated system. In this paper, we present a wireless transceiver for wireless sensor network system, which is considering the link budget for low power design. This hierarchical architecture will make it possible to reconfigurable map application to the WSN system. The accurate pipeline control will advance the performance efficiently, and the adaptive low-power system design will reduce lots of power consumptions. In order to confirm the system, the temperature is regard as the input signals for system performance measurement.

CMOS thermal sensing system with simplified circuits and high accuracy for biomedical application

A low-cost thermal sensor with sigma-delta ADC was realized in 0.25mum CMOS process. Simplify the circuitry with different technologies to improve the efficiency and reduce the error in the thermal sensor chip. Substrate npn transistors are used to sense the temperature and generate the ADCs reference voltage. The ingenious application of sigma-delta ADCs can reduce the complexity of circuit, thereby reducing system cost, area and power consumption. Attach importance to the body temperature (37 plusmn 4 degC), from +33 degC to +42 degC, the inaccuracy is less than plusmn0.15 degC with one-point calibration after packaging. This paper proposes here to further develop this thermal sensor chip (including the calibration of the system) and to use this chip for biomedical application

Wireless Thermal Sensor Network with Adaptive Low Power Design

There is an increasing need to develop flexible, reconfigurable, and intelligent low power wireless sensor network (WSN) system for healthcare applications. Technical advancements in micro-sensors, MEMS devices, low power electronics, and radio frequency circuits have enabled the design and development of such highly integrated system. In this paper, we present our proposed wireless thermal sensor network system, which is separated into control and data paths. Both of these paths have their own transmission frequencies. The control path sends the power and function commands from computer to each sensor elements by 2.4 GHz RF circuits and the data path transmits measured data by 2.4 GHz in sensor layer and 60 GHz in higher layers. This hierarchy architecture would make reconflgurable mapping and pipeline applications on WSN possibly, and the average power consumption can be efficiently reduced about 60 % by using the adaptive technique.

The Implementation of Biotelemetry Chip by Analog Modulation Technique

With the progress of biotechnology wireless technique, the physiological parameters of patients should be monitored and recorded lively without interfering their routine activities. On the basis of this, the low power and easily integrated biotelemetry chip is present in this paper. Besides mixers for modulation needed, the PLL is adopted to make stable carrier in transmitter and lock the shifted phase in receiver, the sixth stage Gm-C BPF and second stage active RC LPF are adopted for channel selector and demodulation in receiver. The specifications of this biotelemetry are: 1) Modulation method: amplitude, 2) Operating frequency: 20 MHz ~ 100MHz 3) Biomedical signal potential sensitivity: 1 mV, 4) Signal input bandwidth: 100 kHz, 5. Power consumption in sensing part: 5 mW. The ECG and PH signals have been served as the input signal for the measurement of the system performance. The chips are fabricated in TSMC 0.35 mum 2P4M CMOS technology