Force-regulated robotic diffuse reflectance spectroscopy scanning

Intraoperative discrimination between malignant and benign tissue is essential for achieving complete tumor resection while preserving healthy structures. Robotic diffuse reflectance spectroscopy (DRS) enables automated intraoperative tissue assessment, but unregulated probe-tissue contact forces introduce spectral artifacts and risk tissue damage, limiting clinical translation.

We present and evaluate an autonomous robotic DRS scanning system incorporating real-time contact force regulation to enable safe, repeatable, and large-area ex vivo tissue assessment.

A serial robot manipulator equipped with a fiber-optic DRS probe, load cell, and camera employed hybrid visual servoing and force feedback control, maintaining 0.08 N target force with $<0.30N$ peak limits. Performance was evaluated on ex vivo bovine and ovine tissues including scanning safety, force regulation versus expert operators, spectral consistency across six novice operators, and tissue classification using support vector machines.

The system achieved 100% and 93% scan completion rates on bovine and ovine tissues, respectively, without visible tissue damage. Autonomous operation enabled 46 continuous trials over $\sim 30\min$ without human intervention. Mean applied force (0.079 N) matched manual sampling (0.080 N) with reduced variance and lower peak forces. Robotic spectral acquisitions aligned with manual measurements, yielding mean inter-observer spectral angles of 1.43 deg, comparable to inter-human operator variability. Tissue classification demonstrated high discriminatory accuracy in bench-top validation.

Force-regulated robotic DRS enables standardized, autonomous tissue scanning with expert-level spectral consistency, advancing spectroscopic sensing toward reliable automated surgical margin assessment.