Wireless telemetry system characterization

Parametric RF Electromagnetics using ANSYS Maxwell

Task

The company Sensimed develops integrated micro-systems for medical devices. In the design process of a new contact lens containing strain gauges that will continuously monitor fluctuations of intraocular pressure, the wireless coupling efficiency between lens sensor and antenna (worn around the eye) had to be calculated as a function of eye position. Furthermore, the influence of antenna geometrical dimensions on equivalent circuit parameters like resistance, inductance matrix and parasitic capacitances of each coil had to be precisely determined in order to guarantee appropriate tuning of the resonant system in the MHz range.

Solution

Running parametric studies in ANSYS Maxwell using 3D eddy current harmonic analyses, and current conduction analyses including surrounding insulator electrical field allowed to calculate all required RLC and coupling parameters as a function of input parameters like eye position and antenna dimensions.
A comparison between calculated and measured inductance values showed an agreement within 0.8%.

Customer Benefit

Following this study Sensimed has gained:

• A useful design to start experimental validation and production without extensive iterative prototyping.
• Increased knowledge about the influence of geometrical dimensions on the resonant circuit tuning.

Consulting_Flyer_Sensimed_Wireless_Telemetry_System_RF_Maxwell_.pdf [2.6MB]