Wireless Temperature Sensor Node Research Articles

Electrostatic generator enhancements for powering IoT nodes via efficient energy management

Electrostatic generators show great potential for powering widely distributed electronic devices in Internet of Things (IoT) applications. However, a critical issue limiting such generators is their high impedance mismatch when coupled to electronics, which results in very low energy utilization efficiency. Here, we present a high-performance energy management unit (EMU) based on a spark-switch tube and a buck converter with an RF inductor. By optimizing the elements and parameters of the EMU, a maximum direct current output power of 79.2 mW m-2 rps-1 was reached for a rotary electret generator with the EMU, achieving 1.2 times greater power output than without the EMU. Furthermore, the maximum power of the contact-separated triboelectric nanogenerator with an EMU is 1.5 times that without the EMU. This excellent performance is attributed to the various optimizations, including utilizing an ultralow-loss spark-switch tube with a proper breakdown voltage, adding a matched input capacitor to enhance available charge, and incorporating an RF inductor to facilitate the high-speed energy transfer process. Based on this extremely efficient EMU, a compact self-powered wireless temperature sensor node was demonstrated to acquire and transmit data every 3.5 s under a slight wind speed of 0.5 m/s. This work greatly promotes the utilization of electrostatic nanogenerators in practical applications, particularly in IoT nodes.

A capacitive electric-field energy harvester with double-layer copper foil for 220V power line

The output power of electric-field energy harvesting is limited by displacement current produced in the capacitive coupling between the harvester and power line. This paper presents a capacitive electric-field energy harvester (CEFEH) that obtains energy from 220V power line by displacement current. The CEFEH consists of copper foil wound around the power line and ground electrode. In order to improve the output power of CEFEH, a double-layer copper foil is used to enhance the capacitive coupling, thereby increasing the displacement current. With the help of larger displacement current, the harvesting power of CEFEH with double-layer copper foil is 1.6 times higher than that of the single-layer copper foil. However, the electric-field energy around the 220V power line is very weak, which makes wireless sensor node unable to work directly. A power management circuit is designed for CEFEH. The test results show that the proposed CEFEH collects 2.468mJ in 400s and drives the ultra-low power wireless temperature sensor node to operation for 800ms. This CEFEH can be used in wireless sensor node with a short-term ultra-low power.

An Accurate Measurement System Comprising of Wireless Thermometers for Neonate Body Temperature Monitoring

This paper addresses the design and implemen¬tation of a real-time monitoring system consisting of wireless thermometers (wireless temperature sensor node) for continuous recording of neonate body temperature in intensive care unit (ICU). Each wireless thermometer incorporates an accurate semiconductor temperature sensor, a transceiver operating on ISM frequency band (i.e., 915 MHz) as well as a microcontroller which is used to control the thermometers functionalities includ¬ing wireless medium access (e.g., free space or body channel), transmission and reception. A voltage regulator and a low-pass filter were also used for removing spurious signals and environmental noise from the thermometer feed line. In order to distinguish the reading of each thermometer from measurements performed by other thermometers, the I-wire protocol was used. This protocol can securely tag the temperature value by incorpo¬rating a unique ID (provided by the manufacturer) into the packet sent wirelessly. An array of two thermometers was implemented and successfully tested in different scenarios, namely free-space, water (immersed thermometers) and on a volunteer’s wrist. Moreover, an in-house developed computer software was used in order to visualize the readings in addition to alerting rapid increase and high body temperature. The software also compares the measurement results with actual values. The agreement between the experimental data and real temperature values is reasonably acceptable and that of the on-body testing is significant. Normal 0 false false false EN-US X-NONE FA

A Self-Powered 3.26-$\mu {\text{W 70}}$-m Wireless Temperature Sensor Node for Power Grid Monitoring

This paper presents a self-powered wireless temperature sensor node for power grid monitoring. With an electromagnetic energy harvester, the node can operate without a battery. In order to reduce the power consumption, several techniques, including deep duty-cycle operation, simple chip architecture with only transmitter, and careful control of sleeping power, are adopted, reducing the average power consumption to only ${\text{3.26}} \mu {\text{W}}$ . The measurement results show that the temperature range is from 0 to 80 °C with a resolution of 0.8 °C. With 2-FSK modulation on the carrier frequency of 433 MHz, the maximum output power is 14.5 dBm, which enables the transmission distance of 70 m, with a bit error rate and packet loss rate of 0.037% and 0.89%, respectively. Similar system architectures and ultralow power (ULP) strategies can be applied to other wireless sensor networks.

Wired/Wireless Hybrid Transmission of BACnet Messages

This paper presents a kind of message conversion method between wired/wireless hybrid network, aiming at meeting the encapsulation and transmission application requirements of Building Automation and Control network (BACnet) protocol messages in ZigBee network. It also proposes a kind of compatible frame structure and addressing method which is specific to wired/wireless network hybrid transmission. It discusses a design of BACnet/ZigBee wireless temperature sensor node from the point of software and hardware, and completes node software and hardware design of BACnet/ZigBee wireless temperature sensor by the embedded system Lm3s6911+, and bidirectional parsing, encapsulating, addressing, sending and receiving process between ZigBee messages and BACnet Ethernet messages are realized. This solution also can extend the current transmission and application range of BACnet messages, and provide an effective way to wired/wireless network hybrid transmission of building automation data.

Self‐Powered Wireless Sensor Node Enabled by a Duck‐Shaped Triboelectric Nanogenerator for Harvesting Water Wave Energy

This paper presents a fully enclosed duck‐shaped triboelectric nanogenerator (TENG) for effectively scavenging energy from random and low‐frequency water waves. The design of the TENG incorporates the freestanding rolling mode and the pitch motion of a duck‐shaped structure generated by incident waves. By investigating the material and structural features, a unit of the TENG device is successfully designed. Furthermore, a hybrid system is constructed using three units of the TENG device. The hybrid system achieves an instantaneous peak current of 65.5 µA with an instantaneous output power density of up to 1.366 W m−2. Following the design, a fluid–solid interaction analysis is carried out on one duck‐shaped TENG to understand the dynamic behavior, mechanical efficiency, and stability of the device under various water wave conditions. In addition, the hybrid system is experimentally tested to enable a commercial wireless temperature sensor node. In summary, the unique duck‐shaped TENG shows a simple, cost‐effective, environmentally friendly, light‐weight, and highly stable system. The newly designed TENG is promising for building a network of generators to harvest existing blue energy in oceans, lakes, and rivers.

A nonlinear MEMS electrostatic kinetic energy harvester for human-powered biomedical devices

This article proposes a silicon-based electrostatic kinetic energy harvester with an ultra-wide operating frequency bandwidth from 1 Hz to 160 Hz. This large bandwidth is obtained, thanks to a miniature tungsten ball impacting with a movable proof mass of silicon. The motion of the silicon proof mass is confined by nonlinear elastic stoppers on the fixed part standing against two protrusions of the proof mass. The electrostatic transducer is made of interdigited-combs with a gap-closing variable capacitance that includes vertical electrets obtained by corona discharge. Below 10 Hz, the e-KEH offers 30.6 nJ per mechanical oscillation at 2 grms, which makes it suitable for powering biomedical devices from human motion. Above 10 Hz and up to 162 Hz, the harvested power is more than 0.5 μW with a maximum of 4.5 μW at 160 Hz. The highest power of 6.6 μW is obtained without the ball at 432 Hz, in accordance with a power density of 142 μW/cm3. We also demonstrate the charging of a 47-μF capacitor to 3.5 V used to power a battery-less wireless temperature sensor node.

Electrodynamic energy harvester for electrical transformer’s temperature monitoring system

The development of an electrodynamic energy harvester (EDEH) for operating a wireless temperature monitoring system for electrical transformer is reported in this work. Analytical modeling, fabrication and characterization of EDEH prototype are performed. The developed EDEH consists of a mild steel core, a wound copper coil and Teflon housing. COMSOL Multiphysics software is used to optimize the design of the harvester. The split-cylindrical design of the developed EDEH permitted the harvester to be wrapped around the output power cable of the electrical transformer without shutting-off the power or disconnecting the power cable. From the electrical transformer, at current levels of 27, 72 and 155 A in the main power line, the energy harvester produced maximum RMS load voltages of 0.356, 1.09 and 2.58 V respectively, when connected to 100 Ω load resistance. However, at matching impedance of 24 Ω (resistance of the coil), the EDEH produced the maximum power levels of 2.99, 19.66 and 112.03 mW for a cable currents of 27, 72 and 155 A respectively. The simulation results of the devised analytical model of the harvester are in good agreement with the experimental results. Moreover, at a cable current of 93 A, when the harvester is connected to the rectifying circuit, the optimum impedance shifted to 185 Ω and the maximum power of 19 mW is generated at that load. The reduction in power generation is attributed to the power consumption of the rectifying circuit. When the rectified DC voltage is used to charge a 3.8 V, Nickel–Cadmium (Ni–Cd) rechargeable battery, it took 3 h to completely charge the battery from 1 to 3.85 V. With the charged battery a wireless temperature sensor node is successfully operated for monitoring the temperature of the electrical transformer.

A wind energy powered wireless temperature sensor node.

A wireless temperature sensor node composed of a piezoelectric wind energy harvester, a temperature sensor, a microcontroller, a power management circuit and a wireless transmitting module was developed. The wind-induced vibration energy harvester with a cuboid chamber of 62 mm × 19.6 mm × 10 mm converts ambient wind energy into electrical energy to power the sensor node. A TMP102 temperature sensor and the MSP430 microcontroller are used to measure the temperature. The power management module consists of LTC3588-1 and LT3009 units. The measured temperature is transmitted by the nRF24l01 transceiver. Experimental results show that the critical wind speed of the harvester was about 5.4 m/s and the output power of the harvester was about 1.59 mW for the electrical load of 20 kΩ at wind speed of 11.2 m/s, which was sufficient to power the wireless sensor node to measure and transmit the temperature every 13 s. When the wind speed increased from 6 m/s to 11.5 m/s, the self-powered wireless sensor node worked normally.

Energy scavenging system utilising MEMS switch for power management

A novel light energy scavenging system is presented, which employs a MEMS switch as the gate driver of a MOSFET in a power management circuit, for scavenging energy in ultra-low light condition. Measurements show that, in a 5lx illumination condition, the wireless temperature sensor node powered by a palm-size solar cell array can autonomously transmit RF data to a receiver 20 m away every 9 minutes. The experimental results demonstrate the most sensitive energy scavenging system ever reported, and offer great potential for realising practical self-sustaining wireless devices.