Optical and Acoustic Coupling Materials and Technologies

This invention describes materials and chemicals with novel, optimal optical and acoustic properties that enable or improve methods that require coupling of light and sound for biomedical and defense applications related to imaging and monitoring therapy. This invention overcomes current limitations by proposing optically and acoustically transparent gel formations, such as gellan gum. In addition, the substitution for water with “heavy water” dramatically reduces the absorption of light due to normal water. These two features not only improve on existing methods that require an efficient coupling medium for imaging, monitoring, modulation methods that use both light and sound but also enable new techniques that may not otherwise be feasible. New techniques include photoacoustic imaging and spectroscopy of lipid and water content deep into tissue. 

The researchers also propose novel solutions for inline photoacoustic “flashlight” adapters that co-align light and sound for optimal photoacoustic imaging—the gellan gum not only provides a stable mechanical interface, but the very low optical scattering coefficient enables shaping of the optics before it reaches the sample to be interrogated. The researchers also provide evidence that optimal coupling materials with a proper design could enable efficient optical imaging of real-time changes in function during ultrasound modulation therapy for treating a variety of medical conditions from traumatic brain injury and stroke to peripheral neuropathy.

Background: 
There are fundamental challenges with efficiently and optimally delivering light and (ultra)sound through coupling materials that are placed between a device that emits and/or detects light and/or sound and coalignment is often desirable. Since air is not an efficient coupling material for (ultra)sound, water-based materials that have similar acoustic properties to tissue are often used for efficient coupling. However, liquid water does not exhibit attractive mechanical properties when integrated into many devices or administered at the tissue interface. As a result, water-based and rubber-based gels are sometimes employed since they possess much better mechanical stability than water. These gels, however, have a variety of undesirable acoustic properties and/or undesirable optical properties. Ultrasound modulation is an emerging field proposed to alter the function of cells and organs; however, the mechanisms and optimal pulse encoding strategies of US modulation are poorly understood, and there are few examples where imaging techniques have been applied in real-time with ultrasound pulse sequences/sound delivery.

Applications: 

• Biomedical applications related to imaging and monitoring therapy
• Ultrasound modulation therapy
• Defense applications related to imaging and monitoring
• Real-time monitoring for traumatic brain injury (TBI), stroke, and peripheral neuropathy

Advantages: 

• Versatile
• Efficient
• Overcomes previous challenges