Open-source, low-cost 3D-printable testbed for in-body optical wireless communications research

This hardware paper introduces an experimental testbed for in-body optical wireless communication (OWC) studies. The conventional version often relies on bulky optical benches and costly supporting equipment, which are often cost-prohibitive for many research institutions. The proposed testbed featured a small footprint, lightweight, a vertically aligned optical path (with fixed optical component placement), and ambient light shielding. It can be printed using commercial 3D printing, reducing costs compared to conventional optical benches. The 3D-printable testbed consists of a box-like chassis that securely positions a near-infrared (NIR) LED TX at the top and a photodetector RX at the bottom, with a tissue sample (e.g., ex-vivo porcine tissue or a tissue-mimicking phantom) held firmly in between. All design files, including CAD and STL formats, along with detailed assembly instructions, are made openly available. The inherent design structure enables faster alignment, and the shields can effectively protect against exposure to indoor ambient light (e.g., typical laboratory lighting), thereby improving experimental reliability. The modular nature of the testbed allows for easy customization to accommodate sensors of different wavelengths and different tissue models. The proposed testbed offers practical benefits and an accessible solution for researchers conducting in-body OWC studies, especially when access to high-end optical equipment is limited.