International Journal of Bioelectronics

Simulation of a Positioning System for Temperature Sensors Used in the Study of Specific Absorption Rate

Abstract

This work presents the design and simulation of an automated precision positioning system for inserting fiber-optic temperature sensors into a SAR (Specific Absorption Rate) phantom. The system enables characterization of temperature distributions under electromagnetic irradiation. The GUI provides 3D visualization, and laboratory measurements target 0.5 °C accuracy within −100 to 330 °C. The simulated positioner supports up to 2 kg and satisfies workspace coverage requirements.

Keywords: Positioning system, Specific Absorption Rate (SAR), temperature measurement, 3D interface.

Introduction

Given the massive adoption of mobile phones, assessing RF exposure requires reliable temperature measurement in phantoms. Conventional sensors (RTDs/thermistors/thermocouples) can suffer EM interference and self-heating; fiber-optic temperature sensors avoid these issues and comply with IEC 62209 procedures for near-body RF exposure measurements.

Methodology

The measurement platform comprises: data acquisition, a positioning control system, motor control and power stages, and a 3D visualization interface. A five-degree-of-freedom robotic-arm positioner was designed in Nylamid (polymer) to minimize EM interference and self-heating. Motion studies in SolidWorks® were used to size motors and verify trajectory coverage (max reach ≈ 1.20 m).

Positioning System

• Architecture: 5-DoF robotic arm (waist, shoulder, elbow, wrist, hand) with full 360° base rotation and constrained shoulder/wrist angles to avoid table collisions.
• Head for sensors: array holding 4 catheters with 1 cm spacing to increase sampling density.
• Motor sizing (simulated with gravity/friction): Motor 1 max torque ≈ 5309 N·mm (≈ 54 kg·cm), power ≈ 17 W; Motor 2 max torque ≈ 27 538 N·mm (≈ 280 kg·cm), power ≈ 87 W.

3D Graphic Interface

A LabVIEW® interface simulates acquisition and mapping of temperatures onto a 3D head model (.stl). The color-scale mapping (default 35–40 °C) allows detection of small changes; virtual sliders emulate four simultaneous probes to test the visualization pipeline and sensor-mapping logic.

Results

Simulations yielded the required dimensions, workspace and torques for the positioner. The GUI accurately mapped synthetic temperature fields from four probes, confirming usability for SAR-related thermal mapping.

Conclusions

The simulated positioner and GUI meet the project goals. However, peak torques (> 100 kg·m cumulative) point to the need to reduce link lengths/weights to lower motor power and cost. Next steps include building the system with fiber-optic sensors to quantify response times and thermal dynamics under RF exposure.

References

See original article for complete references (WHO factsheet; IEC 62209-1/2; optical-fiber thermometry; etc.).

© International Journal of Bioelectronics (IJBIOE). Article licensed under CC BY 4.0.