Development of a Soft Robot Based Photodynamic Therapy for Pancreatic Cancer

Photodynamic therapy (PDT) has received increased attention over the past decades with the potential to noninvasively treat cancer via light exposure. Due to the limited light penetration depth within the tissue (typically less than 1 cm), the PDT optical fiber typically needs to be placed close to the cancerous region to ensure the treatment outcome. In this article, we present a novel soft robot laparoscope design that enables accurate and safe deployment of the PDT optical fiber for pancreatic tumor treatment. To achieve this, the proposed soft robot is able to produce three degrees of freedom motions: linear translation, in-plane bending, and axial rotation. A micro camera is integrated with the soft robot to provide intraoperative image guidance during the procedure. The robot forward kinematics model was obtained via a generalized calibration method, and the differential kinematics was derived analytically. Benchtop characterization results indicated that the soft robot was able to achieve 1.4
$\pm$
0.4 mm position and 1.5
$^{\circ }$

$\pm$
1.1
$^{\circ }$
orientation accuracy, respectively. The robot was experimentally validated in two
in vivo
mice models, and the results indicated that the proposed system successfully reduced the tumor size from 15.3 and 11.8
$\text{mm}^3$
to 12.1 and 4.4
$\text{mm}^3$
, respectively.