An Optical Interferometer-Based Force Sensor System for Enhancing Precision in Epidural Injection Procedure

In minimally invasive pain management proce- dures, precise needle positioning is paramount for effective treatment and patient safety. Traditional techniques like the loss-of-resistance (LOR) method may be insufficient, especially in patients with narrowed epidural spaces. The use of imaging tools such as C-arms carries risks due to radiation exposure for medical professionals. A new system for detecting the epidural space based on optical interferometry is proposed to tackle this issue. Prior research has focused on force measurement systems to identify tissue puncture or rupture. Although mechanical sensors have been utilized, they add bulk and complexity to systems. Optical sensors like Fiber Bragg grating (FBG) and Fabry-Pérot interferometer (FPI) offer stable, high-resolution measurements suitable for complex biological tissues. This study aims to develop a sensor and needle system for epidural injections, incorporating quantitative metrics for validation. An optical interferometer-based force measurement sensor was integrated into a commercial epidural needle, and calibration was performed to establish a correlation between system output and actual force. The system employs a graphical user interface (GUI) to identify puncture points based on abrupt force decreases. A user study involving interventionalists assessed the system’s performance by measuring invasive depth and success rates. The user study demonstrated that the proposed sensorized system could detect the puncture with an average success rate of 72.63 %. This study represents a significant advancement toward safer and more precise epidural proce- dures, addressing critical clinical considerations for practical applications.