A Compact Modified Two-Arm Rectangular Spiral Implantable Antenna Design for ISM Band Biosensing Applications

Area of Science:

• Electromagnetics and Antennas
• Biomedical Engineering
• Wireless Communications

Background:

• Biotelemetric sensing requires miniaturized antennas for implantable applications.
• Existing antennas may lack the necessary performance or compactness for specific biosensing tasks.
• The Industrial, Scientific, and Medical (ISM) band offers a suitable frequency range for such applications.

Purpose of the Study:

• To design and evaluate a novel microstrip implantable antenna (MIA) for ISM band biotelemetric sensing.
• To investigate the performance of a two-arm rectangular spiral (TARS) element in a compact antenna design.
• To assess the antenna's radiation characteristics in a realistic biological environment.

Main Methods:

• A microstrip implantable antenna (MIA) featuring a two-arm rectangular spiral (TARS) element was designed.
• The antenna was simulated using CST Microwave Studio, considering the dielectric properties of rat skin.
• In vitro measurements of the input reflection coefficient were performed using a rat skin-mimicking liquid.

Main Results:

• The proposed TARS-MIA achieved a compact size of 10 × 10 × 2.56 mm³.
• An impedance bandwidth from 2.39 to 2.51 GHz was observed for a 50 Ω system.
• Simulation and in vitro measurement results showed good compatibility, validating the design.

Conclusions:

• The novel TARS-MIA offers a unique geometry and compact size suitable for biotelemetric sensing.
• The antenna exhibits acceptable radiation performance in a simulated realistic biological environment.
• This TARS-MIA presents a viable alternative for ISM-band biosensing operations requiring miniature antennas.