Multiwavelength tissue-mimicking phantoms with tunable vessel pulsation

Area of Science:

• Biomedical Engineering
• Optical Physics
• Materials Science

Background:

• Accurate characterization of optical medical devices requires realistic tissue phantoms.
• Existing phantoms often lack the complex optical and mechanical properties of human skin, including pulsation.

Purpose of the Study:

• To develop a versatile tissue-equivalent phantom for photoplethysmography (PPG) applications.
• To replicate the optical and mechanical characteristics of human skin's epidermis, dermis, and hypodermis.
• To incorporate a pulsatile element mimicking blood flow dynamics.

Main Methods:

• Polydimethylsiloxane (PDMS) base material with varied mixing ratios for mechanical properties.
• Titanium dioxide, India ink, and synthetic melanin for optical property tuning.
• Doctor blade technique for layered structure and molding wires for blood vessel fabrication.
• Integration into an artificial circulatory system with piezo-actuated pumps for pulsation.

Main Results:

• Successfully replicated the optical and mechanical properties of human skin.
• Demonstrated linear dependence of artificial blood vessel diameter on pump actuation.
• Mimicked the time-dependent expansion profiles of real pulse waveforms.

Conclusions:

• A novel tissue-equivalent phantom for ex-vivo testing of opto-medical devices has been successfully demonstrated.
• This phantom provides a valuable tool for the development and routine characterization of optical medical technologies.