A disposable through-needle fiber-optic sensor for in-vivo assessment of deep-tissue biomechanical properties

We report a fiber-optic sensor that can be deployed through a standard 250-µm injection needle (25 gauge) for minimally invasive measurements of deep-tissue biomechanical properties in vivo. We have demonstrated the sensor's ability to provide distinct readouts of muscle stiffness when the hind limb of a rat is relaxed and stretched. To ensure minimal tissue damage and distortion, we have integrated optical proximity sensing within the same fiber for real-time, precise control of the sensor position. To facilitate clinical translation, we have designed the sensor to be disposable and autoclavable and have developed a strategy for mass production.