Ultra-low Power Microcontroller Research Articles

Low‐cost flexible thin‐film detector for medical dosimetry applications

The purpose of this study is to characterize dosimetric properties of thin film photovoltaic sensors as a platform for development of prototype dose verification equipment in radiotherapy. Towards this goal, flexible thin‐film sensors of dose with embedded data acquisition electronics and wireless data transmission are prototyped and tested in kV and MV photon beams. Fundamental dosimetric properties are determined in view of a specific application to dose verification in multiple planes or curved surfaces inside a phantom. Uniqueness of the new thin‐film sensors consists in their mechanical properties, low‐power operation, and low‐cost. They are thinner and more flexible than dosimetric films. In principle, each thin‐film sensor can be fabricated in any size (mm2 – cm2 areas) and shape. Individual sensors can be put together in an array of sensors spreading over large areas and yet being light. Photovoltaic mode of charge collection (of electrons and holes) does not require external electric field applied to the sensor, and this implies simplicity of data acquisition electronics and low power operation. The prototype device use for testing consists of several thin film dose sensors, each of about 1.5 cm×5 cm area, connected to simple readout electronics. Sensitivity of the sensors is determined per unit area and compared to EPID sensitivity, as well as other standard photodiodes. Each sensor independently measures dose and is based on commercially available flexible thin‐film aSi photodiodes. Readout electronics consists of an ultra low‐power microcontroller, radio frequency transmitter, and a low‐noise amplification circuit implemented on a flexible printed circuit board. Detector output is digitized and transmitted wirelessly to an external host computer where it is integrated and processed. A megavoltage medical linear accelerator (Varian Tx) equipped with kilovoltage online imaging system and a Cobalt source are use to irradiate different thin‐film detector sensors in a Solid Water phantom under various irradiation conditions. Different factors are considered in characterization of the device attributes: energies (80 kVp, 130 kVp, 6 MV, 15 MV), dose rates (different ms × mA, 100–600 MU/min), total doses (0.1 cGy‐500 cGy), depths (0.5 cm–20 cm), irradiation angles with respect to the detector surface (0°‐180°), and IMRT tests (closed MLC, sweeping gap). The detector response to MV radiation is both linear with total dose (~1‐400 cGy) and independent of dose rate (100‐600 Mu/min). The sensitivity per unit area of thin‐film sensors is lower than for aSi flat‐panel detectors, but sufficient to acquire stable and accurate signals during irradiations. The proposed thin‐film photodiode system has properties which make it promising for clinical dosimetry. Due to the mechanical flexibility of each sensor and readout electronics, low‐cost, and wireless data acquisition, it could be considered for quality assurance (e.g., IMRT, mechanical linac QA), as well as real‐time dose monitoring in challenging setup configurations, including large area and 3D detection (multiple planes or curved surfaces).PACS number: 87.56.Fc

Design of Side Line Short Circuit Detection Device Load of Low Voltage Circuit Breaker before Closing

It uses MSP430F2274, the ultra low power microcontroller, as the control core of short circuit detection device, through the accurate measurement of low voltage circuit breaker load side of the main wiring of insulation resistance value and the interphase insulation resistance value, outputting high voltage startup sound and light alarm device, and then accomplish the open circuit fault detection. Testing power supply is the use of magnetic coupling resonance principle, from the main power grid electrical insulation for short circuit detection device. The device has the advantages of low cost, small volume, good safety, good detection effect, and can be embedded in use in low voltage circuit breaker.

Stream Selector’s Control System Based on High-Precision Incremental Encoder

For the precision rotor position control of stream selector, a control system based on direct current motor (DC motor) has been constructed. The DC motor, with a high-precision incremental encoder used as the driving force, was assembled with the stream selector rotor through a shaft coupling. Following the motor rotation, the encoder generated two-channel quadrature pulses and one channel index pulses. An ultralow-power consumption microcontroller (msp430f2232) received theses pulses and calculated them. The position of the slot was determined by the number of pulses counted from the index pulse. Operator can set and monitored the slot positions of five stream selectors simultaneously through the program which was written with LabVIEW on the host computer. This module featured high reliability and low power consumption compared with the one driven by step motor. Beyond that, it was much smaller and lighter.

Robust and Efficient OBDH Core Module for the Flexible Picosatellite Bus UWE-3

Pursuing the ambitious goal to establish formations of cooperating small satellites, the University of Wuerzburg established a road map for technology implementations leading towards the realization of coordinated formations of picosatellites. Within the recent developments of the third generation of UWE satellites, special focus was put on the design of a robust and efficient Onboard Data Handling core module. The core module plays a central role in the design philosophy of the UWE-3 bus as it can be seen as the fundamental core which is the only subsystem continuously operating. It is built around two redundant ultra low power microcontrollers in dynamically decided master-slave configuration. One of the main features of the core module software is its flash protection and recovery, where both microcontrollers mutually protect each other by periodically comparing the content of the flash memories with each other and perform corrections if required. This contribution gives a short overview of the UWE-3 picosatellite bus and elaborates in detail on design and test of the OBDH core module.

An <i>In Situ</i> Dissolved Oxygen Monitoring System Based on Fluorescence Quenching Phase Detection

As a major indicator in marine life research and geochemistry, the in-situ monitoring of dissolved oxygen has become increasingly important in the assessment of marine ecosystem. It has been proved that fluorescence quenching may result in shorter fluorescence lifetime. Based on it, this paper proposes an in-situ dissolved oxygen monitoring system of high precision and low power consumption applicable to long-term monitoring of complex marine environment. Using phase detecting method, an AC analog amplification channel on Precision photoelectric detection, and used digital phase detection method and three order integral average method to detect the phase offset. The ultralow-power microcontroller was used to control system. The experiments results show that the system has high stability, high precision(0.02mg/L), quick response time(≤40s), low power consumption(peak current ≤10mA), strong anti interference ability.

A novel compact real time radiation detector

A novel compact real time radiation detector with cost-effective, ultralow power and high sensitivity based on Geiger counter is presented. The power consumption of this detector which employs CMOS electro circuit and ultralow-power microcontroller is down to only 12.8mW. It can identify the presences of 0.22 μCi 60Co at a distance of 1.29m. Furthermore, the detector supports both USB bus and serial interface. It can be used for personal radiation monitoring and also fits the distributed sensor network for radiation detection.

Using SRAM Based FPGAs for Power-Aware High Performance Wireless Sensor Networks

While for years traditional wireless sensor nodes have been based on ultra-low power microcontrollers with sufficient but limited computing power, the complexity and number of tasks of today’s applications are constantly increasing. Increasing the node duty cycle is not feasible in all cases, so in many cases more computing power is required. This extra computing power may be achieved by either more powerful microcontrollers, though more power consumption or, in general, any solution capable of accelerating task execution. At this point, the use of hardware based, and in particular FPGA solutions, might appear as a candidate technology, since though power use is higher compared with lower power devices, execution time is reduced, so energy could be reduced overall. In order to demonstrate this, an innovative WSN node architecture is proposed. This architecture is based on a high performance high capacity state-of-the-art FPGA, which combines the advantages of the intrinsic acceleration provided by the parallelism of hardware devices, the use of partial reconfiguration capabilities, as well as a careful power-aware management system, to show that energy savings for certain higher-end applications can be achieved. Finally, comprehensive tests have been done to validate the platform in terms of performance and power consumption, to proof that better energy efficiency compared to processor based solutions can be achieved, for instance, when encryption is imposed by the application requirements.

Intelligent Capacitive Sensor Array for Removement Detection from Various Surfaces of Tagged Equipment in Hospitals

Knowing the location of special equipment is a big advantage in large hospitals. Active and intelligent removement detection helps to prevents theft and manipulation. Driven by just a coin battery, ultra low power modules extend the battery life to one month and more. An intelligent detection system could adapt on many different surfaces and materials. The main item of the application is an ultra low power Microcontroller from TI, which is driven 99.44% in “sleep mode”. Therefore a high efficient DC/DC converter provides voltage for the controller to work continuously. The sensor itself is build by four single, rectangular shaped capacitive sensor areas. It is possible to differ the change of material in front of its sensitive side and supplying it with only one coin battery one month or longer. With the four sensor elements it is possible to differ between replacement and slip. The component is small and weighs little, so it can be placed directly on skin like a watch or almost invisible on technical equipment. With an additional radio transceiver the replacement of the sensor can be transmitted wirelessly.

笔段式LCD驱动设计

This paper mainly introduces the segment type liquid crystal display principle and control methods in design and application of digital display instrument.The liquid crystal display system made by Texas Instruments with ultra low power microcontroller CC430F6137,which has a segment type LCD controller,can drive 96 segments at most.The GD46532 LCD module is designed by DaLian JiaXian electronic Co.,Ltd.The authors design the driving program in temperature sampling system,and also give the twinkle display way to display the value of sampled temperature.By application testing,the digital instrument with LCD controller can reduce the system size to the largest extent.The system is high reliable.Its program is easily portable in other systems.

Entity Notation: enabling knowledge representations for resource-constrained sensors

The forthcoming ambient systems will contain a large amount of sensors. Representing the data produced by these sensors in a format suitable for ambient intelligence applications would enable a large number of useful services. However, such formats tend to require processing power and communication bandwidth not available in many sensors utilizing ultra low-power microcontrollers and radio chip solutions. This paper presents a lightweight data representation, Entity Notation, to tackle this problem. Sensors with limited computation and communication capabilities can use Entity Notation to describe the data they produce. Entity Notation can be transformed into knowledge representations in a straightforward manner, and hence, the data produced by sensor nodes can be utilized with ease by any ambient intelligence system compatible with the common knowledge representations. This paper presents the design of Entity Notation, its implementations on embedded sensors and the evaluation of its performance.

A Wireless Microbial Fuel Cell Voltage Data Acquisition System Based on MSP430F149

A wireless data acquisition system based on MSP430F149 is developed for the measurement of microbial fuel cells’ voltage. The main function of this system is to convert the analog input voltage into digital output code, process the digital code, and transfer the data through the GSM network or the USB interface. The core of the data acquisition device is a 16-bit general purpose Texas Instruments ultralow-power microcontroller MSP430F149. As the voltage of a microbial fuel cell is very low, the A/D converter circuit is specifically designed for high precision and high accuracy. A real-time clock is used to achieve timing measurement and the time interval can be set to meet demands. The data collected is transferred through the GSM network. Besides, a Windows environment application developed with Visual C++ can be used to access the data stored in the flash memory through USB interface.

Benthic Microbial Fuel Cell as Direct Power Source for an Acoustic Modem and Seawater Oxygen/Temperature Sensor System

Supported by the natural potential difference between anoxic sediment and oxic seawater, benthic microbial fuel cells (BMFCs) promise to be ideal power sources for certain low-power marine sensors and communication devices. In this study a chambered BMFC with a 0.25 m(2) footprint was used to power an acoustic modem interfaced with an oceanographic sensor that measures dissolved oxygen and temperature. The experiment was conducted in Yaquina Bay, Oregon over 50 days. Several improvements were made in the BMFC design and power management system based on lessons learned from earlier prototypes. The energy was harvested by a dynamic gain charge pump circuit that maintains a desired point on the BMFC's power curve and stores the energy in a 200 F supercapacitor. The system also used an ultralow power microcontroller and quartz clock to read the oxygen/temperature sensor hourly, store data with a time stamp, and perform daily polarizations. Data records were transmitted to the surface by the acoustic modem every 1-5 days after receiving an acoustic prompt from a surface hydrophone. After jump-starting energy production with supplemental macroalgae placed in the BMFC's anode chamber, the average power density of the BMFC adjusted to 44 mW/m(2) of seafloor area which is better than past demonstrations at this site. The highest power density was 158 mW/m(2), and the useful energy produced and stored was ≥ 1.7 times the energy required to operate the system.

Zero-Power MEMS Sensor Actuated RFID System*

We present an RFID system with embedded passive MEMS sensor switches to provide long-term, item-level monitoring and data logging. This patented temperature monitoring prototype for blood bag monitoring utilizes MEMS cantilever array both as passive multi-temperature sensors and as power triggers for data logging circuitry, all packaged in a flexible laminated PCB (2.5 × 2.5 × 0.2 cm). This system uses zero power to monitor temperature and uA level current to record temperature data beyond preset thresholds. The on-board data logger consists of a dual-communication, HIPAA compliant, 13.56 MHz RFID chip and customized antenna, an ultra-low power micro-controller, and supporting passives. Prototypes are estimated to have more than 60 days of continued temperature monitoring per use with a thin film battery.

Frequency-feature based antistrong-disturbance signal processing method and system for vortex flowmeter with single sensor

Digital signal processing methods have been applied to vortex flowmeter for extracting the useful information from noisy output of the vortex flow sensor. But these approaches are unavailable when the power of the mechanical vibration noise is larger than that of the vortex flow signal. In order to solve this problem, an antistrong-disturbance signal processing method is proposed based on frequency features of the vortex flow signal and mechanical vibration noise for the vortex flowmeter with single sensor. The frequency bandwidth of the vortex flow signal is different from that of the mechanical vibration noise. The autocorrelation function can represent bandwidth features of the signal and noise. The output of the vortex flow sensor is processed by the spectrum analysis, filtered by bandpass filters, and calculated by autocorrelation function at the fixed delaying time and at tau=0 to obtain ratios. The frequency corresponding to the minimal ratio is regarded as the vortex flow frequency. With an ultralow-power microcontroller, a digital signal processing system is developed to implement the antistrong-disturbance algorithm, and at the same time to ensure low-power and two-wire mode for meeting the requirement of process instrumentation. The water flow-rate calibration and vibration test experiments are conducted, and the experimental results show that both the algorithm and system are effective.

Design of Bowing-Activity Monitoring and Automatic Detection System Using 3-Axis Accelerometer

Abstract - In this paper, a new reliable portable activity monitoring device implemented with the buddhist-style bowing activity and walking step detection algorithm, is presented. In order to monitor the bowing and walking activities, miniaturized 3-axis accelerometer sensor with the sensitivity of 800 mV/g was used. After initial signal conditioning, vector magnitude of accelerometer signals was calculated. Syntactic peak detection method was used in order to feature points. All signal processing algorithms were implemented in ultra-low power microcontroller MSP430 with double precision floating point arithmetic. For evaluation, 19 young man(24.22±5.22 yrs) and woman(22.28±2.72 yrs) were involved. The accuracy of the proposed algorithms were 98.91%(±0.011) for walking step detection and 98.25%(±0.023) for buddhist-style bowing activity. Comparing to the commercialized pedometer accuracy, 87.1%(±0.058), the proposed walking step detection algorithms show more reliable accuracy. Key Words : 108 Bows, Pedometer, Walking Step, Bowing Activity, Wearable Monitor † 교신저자, 정회원 : 건국대 의료생명대 의학공학부 조교수, 건국대 의공학실용기술연구소・공박E-mail : jwlee95@kku.ac.kr* 정 회 원 : 건국대학교 의학공학부 박사과정** 비 회 원 : 경희대학교 체육대학 교수・체육과학박사*** 비 회 원 : (주)지우솔루션 기술연구소 접수일자 : 2010년 4월 26일 최종완료 : 2010년 5월 18일

A Low-Cost Wireless Sensor System and Its Application in Dental Retainers

In this paper, a wireless interrogable sensor device based on an ultra low-power microcontroller for data collection and a radio frequency identification (RFID) interface for data transmission is presented. Wireless sensor systems utilizing RFID transponders offer a new and exciting means of measurement and identification suitable for many biomedical applications. For the majority of these applications, small, inexpensive radio request sensor systems are desirable. In this paper, an ultra-low-power and low-cost wireless temperature data logger system is presented with its application in observing dental retainer use. For this purpose, the retainer's ambient temperature is measured by an integrated sensor and recorded using a microcontroller which acts like a temperature data logger storing the thermal history of several months. For a self powered wireless data transmission from the sensor to the interrogation unit a RFID transponder, operating in the 13.56 MHz ISM band, is used. The presented sensor system includes hard- and software power saving modes reducing the sensor idle current consumption to 1 muA. This allows a battery powered operation of the device for up to two years. For dental and biomedical applications, the device is hermetically sealed using a biocompatible polymeric encapsulation. Results of the first clinical trials observing the patient's dental retainer usage by a set of retainers equipped with the RFID temperature sensor/data logger device are presented. The stored temperature values are analyzed and a clear temperature characteristic indicating the retainer usage was found.

Design of an RFID-Based Battery-Free Programmable Sensing Platform

This paper presents the wireless identification and sensing platform (WISP), which is a programmable battery-free sensing and computational platform designed to explore sensor-enhanced radio frequency identification (RFID) applications. WISP uses a 16-bit ultralow-power microcontroller to perform sensing and computation while exclusively operating from harvested RF energy. Sensors that have successfully been integrated into the WISP platform to date include temperature, ambient light, rectified voltage, and orientation. The microcontroller encodes measurements into an electronic product code (EPC) Class 1 Generation 1 compliant ID and dynamically computes the required 16-bit cyclical redundancy checking (CRC). Finally, WISP emulates the EPC protocol to communicate the ID to the RFID reader. To the authors' knowledge, WISP is the first fully programmable computing platform that can operate using power transmitted from a long-range (UHF) RFID reader and communicate arbitrary multibit data in a single response packet.