Conformal wideband ingestible capsule MIMO antenna system for multi-channel communication in biotelemetry

Abstract

This article presents the design of a compact conformal multiple-input-multiple-output (MIMO) capsule antenna aimed at enabling robust communication and high data rates over a broad frequency range spanning from 0.3 to 2.5 GHz. This range encompasses essential frequency bands such as medical implant communications services (MICS) (401–406 MHz), wireless medical telemetry services (WMTS) (1.4 GHz), and industrial, scientific, and medical (ISM) (0.433 GHz, 0.915 GHz, and 2.45 GHz) for wireless capsule biotelemetry. The size of the capsule is reduced to 17 mm × 7 mm (typically 26 mm × 11 mm) to ensure the safe passage of the capsule without being trapped inside the intestine. The proposed antenna (integrated with dummy electronics to build a fully encased capsule endoscope design) is placed inside homogeneous and heterogeneous phantoms in the simulation. The antenna prototype is fabricated, and performance metrics are measured by implanting it inside pork meat and phantom solution. The proposed MIMO antenna offers a wide impedance bandwidth of ∼2200 MHz, and the measured isolation between the antenna elements is > 20 dB. The proposed antenna is also tested for robustness (interaction between the electronic components and the endoscope’s antenna) and human safety using system considerations and realistic voxel models.