MEMS Thermal & Fluid Control Lab. RFID tag powered by solar cell was set up and integrated with multiple sensors, such as temperature, humidity, light and air velocity sensors. Since the sensor nodes are wireless, they can be easily installed for form a RFID based sensor network. Solar cell UHF tag insert Energy harvesting chip Micro processor for sensor signal processing RFID Sensor Nodes

MEMS Thermal & Fluid Control Lab. Sensor network deployed in a convenience store The energy harvesting wireless sensor network (WSN) was deployed in a 24-hour convenience store to detect thermal comfort degree from the air conditioning control. All sensor nodes are only powered by the indoor lightings in the store. RFID sensor node powered by solar cell 120 mm 100 mm

MEMS Thermal & Fluid Control Lab. Energy saving in the convenience store Constant comfort level control can be achieved and 45% A/C energy can be saved!!

MEMS Thermal & Fluid Control Lab. Data loss of a sensor node powered by harvested energy During one month operation, the data communication status in the store was investigated. Analyzing the packet counts record, the PLR is considered low at 2.3%. This data loss percentage value is comparable with those of sensors powered by battery. Data lost Immediate response time in 75 – 125 ms Transmission delay (ms) 28.8%68.9% 2.3%

MEMS Thermal & Fluid Control Lab. Not only for identification but also for detection RFID is a novel technology for remote identification of goods. The main advantage is the data storage and exchange. In this study, a RFID system was developed for detection of occupant. Through data exchange, the remote reader can get the information of occupancy to adjust the light setting to save energy.

MEMS Thermal & Fluid Control Lab. UHF RFID for occupancy detection Alien RFID Host Alien RFID Tag Name of the product Alien Multi-Port General Purpose RFID Reader Spec of the tagEPC Gen 2; ISO c Frequency MHz – MHz Channel Width500 KHz RF PowerUsing Alien Antenna Max 4 Watt EIRP Transmission interfaceRS-232 (DB-9 F), LAN TCPI/IP (RJ-45) Simple Inputs/Outputs interface 4 inputs 8outputs Operation: under 24 DCV 0.5A Temperature-20°C to +50°C NOTE : Successful operation under the experimental instruction, the valid the distance between Tag and Antenna is 7meter.

MEMS Thermal & Fluid Control Lab. RFID and LED integrated controller RFID Reading Interface LED PWM Controlling Interface IR Mode RFID Mode Monitoring Power Consumption EXIT.

MEMS Thermal & Fluid Control Lab. Characteristics of a LED lamp Power : 44W (Low power) Power factor : (Active Power Supply Design) Color Temperature: 4700K

MEMS Thermal & Fluid Control Lab. LED illumination distribution Unit : Lux LED Lamps 1.8m Test condition

MEMS Thermal & Fluid Control Lab. Circularly Polarized Antenna 3.2M 3M RFID Host 4 AntennaPower input I/O port Power supply & PWM controller Computer Antenna LED control

MEMS Thermal & Fluid Control Lab. RFID based lighting control Metal mesh barrier signal transmitter 100% Brightness Variable brightness modulation Tag % Tag 1. 75% Tag 1. 50% ……….. RFID drive LED controller RFID antenna RFIDTag bracelet Controllable aisle light lighting

MEMS Thermal & Fluid Control Lab. Comparison between IR and RFID Occupancy Detection IR detection cant detect occupant who stand still but RFID can get it. RFID can determine the moving direction of a occupant. IR detector RFID Host No moving nothing IR detector

MEMS Thermal & Fluid Control Lab. RFID-based Occupancy Detection saves more energy than IR-based one LED 500lux 150lux empty RFID Tag 100%30% RFID Antenna

MEMS Thermal & Fluid Control Lab. Conclusions Based on backscatter coupling, used for RFID, zero communication power of the sensor node can be achieved. Through energy harvesting technology, the sensor and related circuits can be enabled. The whole new RFID based sensor networks was demonstrated and employed to record customers comfort degree in a store. The RFID based sensor networks can work as good as the battery powered system.

MEMS Thermal & Fluid Control Lab. Conclusions (conti-) Comparing with the well known protocol – ISO , or so called ZigBee, the RFID based sensor node communication has the advantage on furthermore reducing the power demands. However, different from ZigBee with routing algorithm, RFID based communication is only suitable for the applications of small scale sensor node deployment such like in a store or in your living room.

MEMS Thermal & Fluid Control Lab. Conclusions (conti-) A UHF RFID reader can detect occupants over 7 meters away. A LED lighting system combined with RFID can be used to adjust brightness in different zones and to reach the purpose of energy saving. The deploy and forget scenario was demonstrated by RFID-based sensor networks with energy harvesting chips. There is no need to worry about the replacement of battery.