MEMS Thermal & Fluid Control Lab. 國立台灣大學機械工程系微機械熱流控制實驗室 Department of Mechanical Engineering National Taiwan University, Taipei, Taiwan Department of Mechanical Engineering National Taiwan University, Taipei, Taiwan Sensor-related Energy Saving Technologies Ping-He Chen Professor National Taiwan University Da-Sheng Lee Associate Professor National Taipei University of Science and Technology

MEMS Thermal & Fluid Control Lab. Introduction Sensor networks for energy saving Power consumption of sensor nodes Power Supply for Ubiquitous Sensor Energy harvesting chip Sensor network for energy saving application in a convenience store Energy saving system with RFID and smart lighting Outline

MEMS Thermal & Fluid Control Lab. Introduction Internet of Things Google earth- vedio 中華電信 – HINET of smell, hearing, and feeling sensors, energy provider, communication, carrier, processor, and service.

MEMS Thermal & Fluid Control Lab. Government Policy In 2008, 1% Reduction in CO2 emission in Taiwan, equivalent to 3.9 B KW-h, is achieved only by applying a policy called “Discount in electricity bill by encouraging energy saving of household”. The policy encourages the resident of household to reduce electricity usage by using a simply formula, 5% discount in electricity bill if 95%<ytoy monthly electricity usage ratio (MEUR) <100% 10% discount in electricity bill if 90%<ytoy MEUR < 95% 20% discount in electricity bill if ytoy monthly electricity usage ratio<90%

MEMS Thermal & Fluid Control Lab. User-Friendly Technologies System can be self-adjusted for being operated at its designed efficiency. Electronic devices can be designed to use the least amount of stand-by power. Environment controlled facilities, temperature and humidity, and lighting consume most power in business buildings and residential houses. Therefore, heating, ventilation, air-conditioning, and lighting should be automatically adjusted to a condition that is reasonably comfortable to the resident.

MEMS Thermal & Fluid Control Lab. Sensor Networks for Energy Saving in a Living Space It requires a sensor network to keep resident in a living space comfort but to consume the least energy. Heating, ventilation, air conditioning, and lighting can be controlled by distributed control units. We require a sensor network that has a microchip for harvesting energy from environment, and a microprocessor for analyzing the data, and a RF module for having remote communication capability.

MEMS Thermal & Fluid Control Lab. Traditional Building Automation System Heating, ventilation, air-conditioning, and lighting of a living space are controlled by a centralized unit without information in each distributed zone, for instance, an office building. Sensor Networks for Energy Saving in a Living Space

MEMS Thermal & Fluid Control Lab. Smart Building Automation System with a sensor network Distributed sensors and distributed control units Flexible

MEMS Thermal & Fluid Control Lab. Requirement of Distributed Sensor Nodes Easy Installation Inexpensive Wireless No maintenance of battery

MEMS Thermal & Fluid Control Lab. Power Supply of Sensor Node Recent achievements in wireless communications have enabled easy installation of sensor networks. Although wireless communication of sensor node can be achievement by the development of RF technologies, the sensor node power supply, through either power lines or battery power, still presents obstacles in the development of sensor networks. To allow the deployment of sensor become simple and durable, the power supply to the sensor node should be both wireless and no battery.

MEMS Thermal & Fluid Control Lab. Sensor node power consumption (conti.) To date, most sensor nodes are active and use alkaline batteries as sources of energy. These batteries have fixed electricity storage, which limits the sensor node’s life time, and thus, they have to be replaced. Often, the cost of physically deploying resources to replace worn out battery outweighs the cost of the node itself. To make matters worse, the used battery causes serious environmental pollution.

MEMS Thermal & Fluid Control Lab. Power Supply for Ubiquitous Sensing Ambient energy harvesting is a possible solution in the development of wireless sensor networks. Scavenging energy from renewable sources near the sensor node could be the best method for providing power to the sensor. Reducing the power consumption of the sensor node becomes a key issue!! No battery!! Sensor node

MEMS Thermal & Fluid Control Lab. Communication of Sensor node powered by EM Coupling RFID communications rely on electromagnetic coupling Backscatter coupling can transmit energy to tags as far as 5 meters away. The special communication scheme was expected to apply for sensor networks to eliminate the battery required by node. Features of passive UHF RFID system: Coupling communication & remote energy transfer to tags

MEMS Thermal & Fluid Control Lab. Comm. protocol Comm. band Data rate PowerSecurityApplications Home RF 2.45 GHz 1-2 Mbps 100 mW 50 Hz hopping Wireless communications of home appliances Blue- tooth 2.45 GHz 1-3 Mbps 1-10 mW 128 bit key Handheld devices communications Zig Bee 868/ 915 MHz 2.45 GHz 0.02, 0.04, 0.25 Mbps 1-3 mW 32, 64, 128 bit key Low power and low data transfer rate communication protocol for building automation RFID 135 kHz / 915 MHz 2.45/ 5.8 GHz Mbps Passive tag powered by EM coupling 32, 64, 128 bit key Logistics and supply chain management Power Consumption of Different Communication Protocols

MEMS Thermal & Fluid Control Lab. ZigBee v.s. RFID ISO enabled a low data transfer rate, low power and low cost sensor networks. The advantage of ZigBee chip is the high efficient routing for large area deployment. Semi-passive RFID using ISO A,B,C for long range detection of the tags. Suitable for data gathering in the residential area.

MEMS Thermal & Fluid Control Lab. Commercial products as known as class 3 tags were available on market for integrating sensor apps. Such kinds of product still need batteries to supply power for sensor, micro processor and related circuits. How to build a batteryless power solution for sensor nodes is a key challenge.

MEMS Thermal & Fluid Control Lab. RFID Sensor Node Charged with Energy Harvesting Chip The environmental energy sources supply power in irregular, random, and burst charging. The RFID tag enabled by harvested energy is required to capture and transfer intermittent low energy bursts to become stable power supply for normal operation.