Development of Passive Moisture Sensor
Rahman, S M Musfequr (2020)
2020
Master's Programme in Electrical Engineering
Informaatioteknologian ja viestinnän tiedekunta - Faculty of Information Technology and Communication Sciences
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Hyväksymispäivämäärä
2020-12-29
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202012189010
https://urn.fi/URN:NBN:fi:tuni-202012189010
Tiivistelmä
A sensor acts as a connecting medium between the physical world and electrical devices. Based on the power source, there are two types of sensors: active and passive. The passive sensor does not require any direct power source, and it is a less expensive device. Radio Frequency Identification (RFID) is a low-cost, reliable, and fast technology that uses radiofrequency to track down objects and their position. Passive ultra-high frequency (UHF) RFID tags are fast in object tracking, which can operate from several meters distance. To activate the passive tags it required the radio frequency from the RFID reader. Passive UHF RFID tags are extensively used in supply chain management, object tracking, etc. Due to low power data transmission capability, it is used in wireless sensing technology.
Electronic waste is one of the leading causes of environmental pollution. In this thesis, the main goal was to implement and test a low-cost, environment-friendly moisture sensor. We manufactured passive UHF RFID tag on low-cost materials, i.e., commercially available dishwashing cloths as substrates. Three different substrate materials were used for moisture sensor fabrication. By using conductive thread and embroidery techniques, the moisture sensors were fabricated. In cases where hand stitching methods were complicated, the embroidery machine was used to fabricate the moisture sensors. For moisture testing, two methods were applied: submerging in water and spraying water. The soluble thread was used to give a circular shape to the moisture sensor tags to observe the bending effect and the substrate's shape-changing tendency after the moisture test on the sensor tags.
In this thesis, mainly, three tests were performed to observe the moisture sensor tags' performance in different conditions. Firstly, all the sensors' tags were tested for observing the bending effect on the substrate materials. It was observed that all the materials had similar bending effects, and their read range decreased due to the increase of bending on the sensor tags. Secondly, moisture sensor tags of all the three materials were tested during initial dry, wet, and redried conditions without bending the moisture sensor tags. When redried from the wet condition, the moisture sensor tags' read ranges were improved but could not reach the level of initial dry condition. Compared to all the three substrate materials of moisture sensor tags, Material-2 showed better performance after the moisture testing on the tags. Finally, the moisture sensor tags were tested in a combination of bending and wet conditions. All the tags were tested in two different positions like sidewise bending and hanging from the top in bending condition. In both cases, Material-2 demonstrated better performance when compared to the other two materials.
To conclude, though all the moisture sensor tags showed sensing properties within the UHF RFID band, for moisture sensor tag development, “Mikrokuituinen Iisi sieniliina” (Material-2) was better of the three materials, whereas “Talousliina 3m” (Material-3) is the least preferred.
Keywords: RFID, UHF, Passive tags, Dishwashing cloth, Moisture sensor
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Electronic waste is one of the leading causes of environmental pollution. In this thesis, the main goal was to implement and test a low-cost, environment-friendly moisture sensor. We manufactured passive UHF RFID tag on low-cost materials, i.e., commercially available dishwashing cloths as substrates. Three different substrate materials were used for moisture sensor fabrication. By using conductive thread and embroidery techniques, the moisture sensors were fabricated. In cases where hand stitching methods were complicated, the embroidery machine was used to fabricate the moisture sensors. For moisture testing, two methods were applied: submerging in water and spraying water. The soluble thread was used to give a circular shape to the moisture sensor tags to observe the bending effect and the substrate's shape-changing tendency after the moisture test on the sensor tags.
In this thesis, mainly, three tests were performed to observe the moisture sensor tags' performance in different conditions. Firstly, all the sensors' tags were tested for observing the bending effect on the substrate materials. It was observed that all the materials had similar bending effects, and their read range decreased due to the increase of bending on the sensor tags. Secondly, moisture sensor tags of all the three materials were tested during initial dry, wet, and redried conditions without bending the moisture sensor tags. When redried from the wet condition, the moisture sensor tags' read ranges were improved but could not reach the level of initial dry condition. Compared to all the three substrate materials of moisture sensor tags, Material-2 showed better performance after the moisture testing on the tags. Finally, the moisture sensor tags were tested in a combination of bending and wet conditions. All the tags were tested in two different positions like sidewise bending and hanging from the top in bending condition. In both cases, Material-2 demonstrated better performance when compared to the other two materials.
To conclude, though all the moisture sensor tags showed sensing properties within the UHF RFID band, for moisture sensor tag development, “Mikrokuituinen Iisi sieniliina” (Material-2) was better of the three materials, whereas “Talousliina 3m” (Material-3) is the least preferred.
Keywords: RFID, UHF, Passive tags, Dishwashing cloth, Moisture sensor
The originality of this thesis has been checked using the Turnitin OriginalityCheck service.