Open-source, Low-cost 3D-Printable Testbed for Optical-based In-body Communication Research

Typically, studies on optical wireless communication (OWC) employ high-end components, including an optical bench and its accessories. Using such properties in in-body OWC studies presents challenges, i.e., from a cost, ergonomic, and technical perspective. The optical bench is bulky, rigid, and unaffordable, with a large footprint that is oversized for such short-range and confined beam requirements. In-body OWC is sensitive to optical alignment and requires shielding experiments from ambient light to mitigate light interference (e.g., normal laboratory room lighting). Achieving a misalignment-free setup requires careful manual tuning, which consumes setup time and is susceptible to errors. These issues become worse in dark environments, where experiments are conducted, potentially causing eye strain and discomfort after long testing periods. Thanks to the availability of consumer-grade 3D printing technologies, an alternative testbed can be produced more affordably than commercial products, and with greater openness. Here, we propose a 3D-printable testbed for an in-body OWC experiment that offers several benefits, including low cost, open-source design, ambient light shielding, and facilitates faster and more accurate optical alignment setup, thereby reducing setup time. Additionally, the proposed testbed allows researchers to perform experiments under normal lighting conditions without compromising measurement accuracy. As a result, this significantly improves researcher comfort and eye health by eliminating the need to turn off laboratory lighting.

The repository includes the following files, all of which are openly shared to support replication by the research community:
1. 3D-printable design files: contains 3D printable models for the top mount, chassis, and leg supports (3 mm and 20 mm). Files are support-free for standard PLA printing.
2. Illustrative figures of the build instructions.
3. Supplementary Data 1: Contains (a) raw data in XLS files, which are empirical data of optical power measurements of NIR LED 850 nm and 810 nm under controlled experiments (i.e., varied drive currents and ambient lighting conditions: ON v.s. OFF). The testbed enables reproducible experiments under both ambient light ON and OFF conditions. We also provide MATLAB scripts for statistical analysis and plotting with error bars under 850 nm and 810 nm NIR LEDs. The measurement employs a Thorlabs optical sensor (S121C) integrated with an optical power meter (PM100D), for which the settings can be found in [1], [2].