A Fluidically Tunable Metasurface Absorber for Flexible Large-Scale Wireless Ethanol Sensor Applications.

Area of Science:

• Metamaterials and Nanotechnology
• Chemical Sensing
• Microwave Engineering

Background:

• Metasurface absorbers offer unique electromagnetic properties.
• Remote chemical sensing requires sensitive and tunable detection methods.
• Flexible and inkjet-printable materials are desirable for large-scale applications.

Purpose of the Study:

• To propose a novel flexible tunable metasurface absorber for remote ethanol sensing.
• To investigate the use of periodic split-ring-cross resonators (SRCRs) and microfluidic channels for chemical detection.
• To demonstrate the absorber's capability to detect changes in effective permittivity and resonant frequencies.

Main Methods:

• Inkjet printing of silver nanoparticle inks for SRCR patterns on paper.
• Laser etching of microfluidic channels on polydimethylsiloxane (PDMS).
• Full-wave simulation and experimental measurements to validate performance.

Main Results:

• The metasurface absorber exhibits a resonant frequency shift from 8.9 GHz to 10.04 GHz with 0% to 100% ethanol concentration.
• A linear frequency shift was observed for ethanol concentrations ranging from 20% to 80%.
• The absorber effectively detects changes in the effective permittivity of different liquids.

Conclusions:

• The proposed flexible tunable metasurface absorber is suitable for large-scale remote ethanol sensing applications.
• The device demonstrates tunable resonant frequencies based on liquid permittivity changes.
• Inkjet printing and laser etching offer a viable fabrication route for such sensors.