High-Sensitive Microwave Humidity Sensor Using Polyvinyl Alcohol/Carboxymethyl Cellulose (PVA/CMC) Composites

Area of Science:

• Materials Science
• Electrical Engineering
• Sensor Technology

Background:

• Microwave sensors offer unique detection capabilities.
• Polyvinyl alcohol (PVA) and carboxymethyl cellulose (CMC) are polymers with potential sensing applications.
• Developing advanced humidity sensors is crucial for environmental monitoring and industrial processes.

Purpose of the Study:

• To investigate the humidity sensing properties of microwave sensors coated with PVA/CMC composites.
• To determine the effect of varying PVA/CMC weight percentages on sensor performance.
• To compare the performance of PVA/CMC composites with pure PVA and pure CMC for humidity sensing.

Main Methods:

• Fabrication of microwave sensors utilizing a microstrip transmission line with an interdigital capacitor-defected ground structure (IDC-DGS).
• Coating the sensors with PVA/CMC composites at different weight percentages (100/0, 90/10, 80/20, 60/40, 0/100).
• Measuring changes in resonant frequency and transmission coefficient magnitude under varying relative humidity (40%-90%) at ~25 °C.

Main Results:

• Humidity sensing capability, indicated by variations in resonant frequency and transmission coefficient magnitude, increased with higher CMC content.
• Pure CMC exhibited enhanced humidity sensing performance compared to PVA and gelatin.
• The percent relative frequency shift and effective relative permittivity improved with increased CMC concentration.

Conclusions:

• PVA/CMC composites are effective for humidity sensing applications using microwave sensors.
• Increasing CMC content in PVA/CMC composites significantly enhances humidity sensing performance.
• Pure CMC demonstrates superior humidity sensing capabilities, making it a promising material for advanced sensor development.