| With the expansion in number and requirements of modern wireless communications, the technology related to their associated antennas has been continuously improved. Printed antenna with advantages such as compact structure, easy integration, conformal and equipment, easy preparation, has been widely used in various fields such as communication, radar, navigation, biomedical. In addition, their straightforward integration with electronics has opened new fields of application such as smart sensing systems. Printed antennas can be used in different parts of a wireless smart sensor as a radio link, sensing element, or even as energy harvester. This paper studied the performance of printed antennas, wireless gas sensor and wireless stain sensor.The first part of the study according to the basic principles of printed antenna, a series of antennas whose frequency range from 0.4 to 3.9 GHz were designed and simulated by HFSS microwave simulation software. Flexible printing technology was applied to print these antennas on PI substrate with nano-silver ink. Agilent 5061 B was used to test these antennas. We compared and analyzed the test results with the simulation values and the design values. From the overall comparison results, the obtained fixed-frequency printed antennas S11 parameters within its operating bandwidth of less than-20 d B, antenna gain greater than 1.5 d Bi. This means that they can be applied to the field of sensors, which lay foundation for subsequent the printed wireless smart sensor research.The second part of the paper printed wireless NO2 gas sensors flexible gravure printing technology and pencil-trace on weighing paper with printed silver interdigitated electrodes(Ag IDE) for NO2 gas sensors, and studied the performance of its gas sensing. We chose a center frequency of 2.68 GHz antenna as printed wireless NO2 gas sensors radio signal transmission antenna, with tungsten trioxide /poly(3, 4-ethylenedioxythiophene) /poly(styrenesulfonate)(WO3/PEDOT/PSS) and reduced graphene oxide /poly(3, 4-ethylenedioxythiophene)/poly(styrenesulfonate)(S-Ag-RGO/PEDOT/PSS) these two composites were used as NO2 gas sensing material. Printed wireless NO2 gas sensor was prepared by gravure printing technology. Printed WO3/PEDOT/PSS-based wireless NO2 sensor has a high gas sensing response to the 1-4 ppm NO2 gas. Its resonant frequency and return loss S11 with increasing NO2 gas concentration increases linearly; at 1 ppm NO2 gas, its resonant frequency changed 63 MHz, return loss changed the 3 d B. At 4 ppm NO2 gas, the sensor resonance frequency offsets of up to 355 MHz, return loss increased by 14 d B. At 1-4 ppm NO2 gas, return loss of printed formula S-Ag-RGO/PEDOT/PSSbased wireless NO2 sensor increases linearly with increasing NO2 gas concentrations. When 1 ppm, printed antenna resonant frequency decreased 103 MHz, return loss increased 3 d B. Wireless detection reading distance of printed wireless NO2 gas sensor is 0.8 m. Thus, we successfully prepared with a high response printed wireless NO2 sensor for low concentrations of NO2. In addition, we had also prepared a pencil-drawed NO2 sensing element, which consists of the printed silver interdigital electrodes on weigh paper and pencil-trace; the printed Ag IDEs not only offer a low resistance but also provide the assembly of Ag NPs into exfoliated graphene sheets for the paper-based NO2 gas sensors. The sensor on Ag IDEs showed the higher gas-sensing response S of 8.34% to 5 ppm of NO2, over 5 times in comparison to that of the sensors directly on weighing paper. The combination of advantages of the pencil drawn sensor and Zig Bee wireless module makes them suitable platform for deployed wireless environmental monitoring.The third part of the paper studied S-RGO printed antenna parameters and their response to stress on the elastic substrate. We prepared the center frequency of 2.47 GHz printed antenna on the material with gravure-printed S-RGO conductive ink embedded in the surface layer of the elastic latex and nitrile butadiene rubber(NBR) substrate. Contrast the two substrates printed antenna pattern resolution, we choose a more suitable preparation S-RGO printed antenna of NBR as a substrate. Contrast printed antenna pattern resolution on both the substrate, we chose NBR as more suitable the substrate for the preparation of S-RGO printed antenna. And we characterized based on NBR substrate S-RGO printed antenna film sheet resistance, print thickness and microstructure. Based S-RGO special properties, S-RGO printed antenna was acted as a wireless stress sensor; When external force was loaded, the S-RGO could be easily deformed, which caused the changes of electrical properties of the sensor. A wired stress test and a wireless stress test were done to the sensor. Normalized resistance value of printed S-RGO stress sensor exponentially increased 0.2% to 2 % of a different strain in the cable test. At 2% strain, normalized resistance value of the sensor was 50, the gauge factor reached up to 6200. Furthermore, Test results from the stress sensor to brush across, normal healthy adult males beat and pulse after pulse beat movement, body bent fingers strained means that had a rapid detection of micro-strain of performance. This performance was a prerequisite for wireless testing, showed S-RGO film having excellent stress sensitivity. Wireless Test results showed, printed S-RGO stress sensor antenna had a high signal transmission performance, the return loss at the resonance frequency was-35 d B, the antenna gain was 2.68 d B, voltage standing wave ratio VSWR was 1.02, and antenna transmission efficiency was 99%. The resonance frequency and return loss changes of printed S-RGO stress sensor were recorded of Agilent 5071 B vector network analyzer via wireless communication to the strain of normal male pulse, blink, breath, sound, bending refers to physical activity. Thus, as a radio stress sensor element, printed S-RGO antenna had a high sensitivity and rapid response strain response. This would be have a certain reference that printed stress sensor for wireless applications in intelligent electronic skin.In this paper, the antennas based on flexible gravure printing technology have good performance, the prepared wireless NO2 gas sensor can be monitored in real time by low concentrations of NO2 wirelessly, the printed wireless strain sensor has high sensitivity Micro-stress which can be tested by wireless monitoring, provide an experimental basis for printed wireless smart sensor and its application in the intelligent electronic skin. |
PDF Full Text Request