Design of a Non-Invasive Optical Probe for Tissue Characterization

The ability to non-invasively characterize biological tissues is essential for early disease detection, monitoring, and diagnostic applications. This study presents the design and development of a non-invasive optical probe for tissue characterization based on light-tissue interactions. The system incorporates surface-mount device (SMD) LEDs emitting at 460 nm, 540 nm, 660 nm, and 950 nm, positioned at varying distances (3.40 mm, 5.50 mm, 7.60 mm, and 9.70 mm) from the photodetector to selectively probe different tissue depths. A silicon photodiode (BPW34) detects the reflected light, which is then processed through a transimpedance amplifier (LM358) and an Arduino microcontroller. To validate the probe’s performance, a skin-mimicking phantom containing pigmented chromophore is developed. Experimental results demonstrated a predictable decrease in detected signal with increasing source-detector distance and phantom depth, confirming the system’s capability to differentiate between superficial and deeper tissue layers. The proposed design offers a cost-effective, portable, and efficient solution for non-invasive tissue assessment, making it suitable for various biomedical applications.