# Applications of Nanomaterials in RFID Wireless Sensor Components
## 5 Applications
### Agriculture  
As the scale of farms expands, the need for effective management and supervision in agriculture has become increasingly essential. RFID sensor tags can detect various environmental parameters such as temperature, humidity, and light. Through their large-scale information processing capabilities, they enhance the efficiency of crop and environmental management.  
[PERSON] et al. developed a passive RFID sensor tag for soil moisture monitoring (Figure 13a) [128]. They first formed a thin-film circuit on a silicon substrate through lithography, sputtering, and lift-off processes to establish the foundation for measuring soil impedance and fringe capacitance. Subsequently, they coated the sensor with TiO\({}_{2}\) nanoparticles for humidity measurement. The functionalization using TiO\({}_{2}\) nanoparticles achieved significant sensitivity, especially at humidity levels exceeding 50%RH. This sensor operates independently of soil composition and effectively measures various soil moisture levels without the need for frequent calibration.  
[PERSON] et al. designed a humidity sensor using Ag nanoparticles and poly (2-hydroxyethyl methacrylate) (pHEMA) (Figure 13b) [100]. The sensor, printed on a flexible PET substrate, introduced Ag nanoparticles as interdigitated capacitors. Following this, they deposited humidity-sensitive pHEMA on the interdigitated capacitors with a fixed thickness. This sensor exhibited excellent linearity in humidity measurements, ranging from 30%RH to 80%RH, with a maximum error range of 0.6 to 0.8%, demonstrating its stability. This sensor is expected to be actively used in the smart agriculture field.  
[PERSON] et al. implemented a multifunctional sensor capable of detecting humidity, temperature, light, and CO\({}_{2}\) gas (HTLC) by combining various nanomaterials (Figure 13c) [121]. Composites composed of pure SnO\({}_{2}\), MoS\({}_{2}\), ZnO, TiO\({}_{2}\), Co\({}_{3}\)O\({}_{4}\), In2O\({}_{3}\), CuO, and RGO solutions were manufactured using a thermal method. By combining these materials, the researchers created sensors with specific characteristics, such as SnO\({}_{2}\)/MoS\({}_{2}\)/RGO for humidity detection, ZnO/MoS\({}_{2}\)/RGO for temperature sensitivity, TiO\({}_{2}\)/Co\({}_{3}\)O\({}_{4}\)/RGO  
Figure 12: (**a**) Digital-to-digital capacitor system cast from wheat gluten and its CO\({}_{2}\) monitoring performance [99]. (**b**) Schematic diagram of liquid food supply chain monitoring sensor using gold nanoparticle marker and frequency shift according to d-AuNP concentration. (**c**) RFID-combined manual digital sensors for packaged foods and direct probing for ammonia detection. (**d**) Nanostructure conductive polymer-based food spoilage sensors and their ammonia, cadaverine, and putrescine selectivity [103].  
for light intensity sensitivity, and In\({}_{2}\)O\({}_{3}\)/CuO/RGO for CO\({}_{2}\) gas sensitivity. Each environmental parameter was measured at separate frequencies or amplitudes, ensuring no interference. The HTLC multidimensional sensor based on RFID systems is expected to effectively monitor complex agricultural environments.  
[PERSON] et al. utilized graphene-based films to construct an effective system for agriculture information monitoring (Figure 13d) [113]. They proposed a system capable of real-time collection and transmission of diverse and large amounts of data through wireless networks of various sensors. Among the numerous sensors, those utilizing graphene active films demonstrated non-destructive and accurate monitoring of leaf moisture. The high surface area of graphene effectively increased the monitoring sensitivity of the sensor. Consequently, the real-time and mass information processing capabilities of RFID systems contribute to the systematic management of the agricultural field, where monitoring of various environmental variables is crucial.