Monitoring Forces in Soft Robotic Brain Retraction via Origami Sensing Modules

To safely access deeper regions of the brain for proce- dures like tumor resection, surgeons must displace (i.e., retract) healthy tissues usually through the use of rigid, metal spatulas [1]. However, required retraction forces up to 2.5 N have been shown to increase intracranial pressures beyond the safe range of ≈ 2-3.3 kPa and cause neurological complications when applied over sustained durations [1], [2]. Soft robots have shown the potential to address the need for safer access in neurosurgery by leveraging their inherently safe tissue interactions for tasks such as deploying electrocorticography arrays [3] and navigating brain vasculature [4]. However, there remains a need to quantitatively monitor retraction forces so as not to cause injury to healthy brain tissue. In our previous work, we introduced a soft robotic retractor that distributed retraction forces and generated a sur- gical workspace through origami-inspired actuation [5]. Here, we present origami sensing modules (OSM) with the ability to monitor tissue interaction forces of the soft robotic retractor via a capacitive sensing modality (Fig. 1). The OSM folds with the elliptical Miura origami pattern of the robot so that contraction/expansion over vacuum pressures and stiffening over positive pressures can retract tissue while monitoring forces (Fig. 1A). By implementing force sensing into the soft robotic retractor, the proposed OSMs seek to reduce unintended trauma and improve the overall safety of tissue retraction in neurosurgical procedures.