A novel low-cost chipless RFID tag sensor is presented. The tag sensor provides identification data as well as monitors relative humidity (RH) of tagged objects. The tag sensor is made of passive microwave circuit that uses humidity sensitive polymer material for RH sensing. The aim of this paper is to investigate RF sensing properties of moisture absorbing polymer polyvinyl alcohol (PVA) at microwave frequency. Moreover, frequency shifting technique is used to encode data bits for high data capacity. The overall size of the proposed tag sensor is 15mm x 6.8 mm and has 6 bit data capacity for ID generation and single bit for humidity sensing. Results presented here show about 607 MHz frequency deviation for 50% RH increase. The tag sensor has potential to be printed on flexible laminates like plastic and paper for ultra-low cost item level tagging and ubiquitous sensing.

Abstract-A highly sensitive, passive relative humidity (RH) sensor using polyvinyl-alcohol (PVA) dielectric film is presented. For the first time, PVA is investigated in microwave RF sensing devices for low cost, high resolution and accurate chipless RH sensor realization. Comparative study with traditional humidity sensing Kapton polymer is presented to validate superior performance of PVA film. Results are presented for two different passive high Q resonators to validate sensing performance in wide applications. Moreover, a new sensing parameter is described to investigate sensitivity measurement through resonance frequency and Q factor variation. The RH sensor has the potential to be integrated with mm and µm-wave high frequency passive RFID for ubiquitous sensing.

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In this paper a fully printable low cost chipless RFID temperature sensor is presented. The chipless RFID comprises of multiresonator spirals coupled with a microstrip line. Each spiral represents a single data bit and the number of cascaded spirals corresponds to the number of bits it can store. The integration of temperature sensing is performed by utilizing the resonant frequency of a specific spiral of the tag. Unlike earlier reported works on chipless RFID temperature sensor our proposed sensor does not require any external circuitry or semiconductor chip for sensing environment temperature. Rather, it performs real time temperature sensing using the dielectric property of temperature dependent high K polyamides. Introducing high K dielectric material changes the equivalent capacitance of the LC resonator which varies with environment temperature. Results verify that a dedicated resonator can perform the sensing whereas the other cascaded resonators resemble the ID of the tag.I.

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The looming energy crisis, heightened by the continuing depletion of fossil fuels, accentuates the need for deployment of renewable energy resources in Bangladesh, now more than ever before. Though hydrocarbon resources in the country are limited, the substantial availability of renewable energy sources in the form of solar, biomass, hydropower and wind energy offers opportunities of sustainable energy based development. Motivated by this auspice, the government of Bangladesh and different non-government organizations have been working towards the dissemination of renewable energy based technologies throughout the country. Though this diffusion of renewable energy sources is yet to assume extensive commercial dimensions and widespread implementations, the advancement has been significant in recent years. With the objective of reviewing this progress, this paper presents a comprehensive study of the contemporary renewable energy scenario in Bangladesh in terms of distribution, research and infrastructural development in the country. In addition to this, installed capacity has been calculated to assess the relative contributions of the five renewable energy sectors of Bangladesh.