A Microrobot With an Attached Micro-Force Sensor for Natural Orifice Access to the Bladder Interior Wall

Abstract

In this work, we present the conceptual design of a 3.5mm outside diameter cable-driven hyper-redundant robotic manipulator with an attached micro-force sensor at the tip for application in transurethral palpation of any targeted area of the bladder interior wall tissue. The stain-gauge based micro-force sensor is designed using finite element analysis (safety factor > 3.5 and load capacity of 0.8N) and subsequently prototyped using additive manufacturing. Sensor components were prototyped using additive and traditional manufacturing, assembled and characterized using a data acquisition environment. The performance of the finite element and prototyped sensor was almost identical. The characterized sensor was used to evaluate tissue properties. The concept of a hyper-redundant 10-joint 6-DOF manipulator comprising of a 5-DOF rigid and a 5-DOF continuum segment is presented along with the forward and inverse kinematics analyses. The inverse kinematics is performed using a Jacobian based formulation to limit the possibilities of singularities. Studies employing the proposed inverse kinematics analysis demonstrated the ability of the manipulator to engage with any area in the bladder and especially the difficult to reach trigone area while attaining a normal pose at the point of contact. A normal pose is required for properly interrogating the tissue with the uniaxial force sensor. The proposed manipulator and force sensor system as presented suggest a probable solution for quantitatively evaluating localized biomechanical properties of the bladder interior wall tissue as a means towards improving treatment and providing better patient care. An initial limited functionality prototype demonstrates capabilities of the proposed concept and provides confidence for further research to fully realize the proposed concept.

Design, Prototyping, and Characterization of a Micro-Force Sensor Intended for Tissue Assessment in Confined Spaces

“…1, consists of three major components; sensor head, sensor base, and sensing element. The sensor base component is intended to be attached to the manipulator researched by Adejokun et al [33], [34], [35]. When the manipulator palpates the target tissue, the sensor head will translate along the loading axis (global Y-axis) and engage with the sensing element at location D as presented in Fig.…”

“…Rigid link manipulators have limited capability to interrogate the entire bladder through contact palpation, as such a 10-joint 6-degree of freedom compliant manipulator was proposed to access the 'difficult-to-reach' areas within the bladder including the trigone [33]. Adejokun et al presented a compliant robotic manipulator for bladder contact palpation through the urethra with an overall diameter of 4 mm [33], [34], [35]. The sensor presented in this research is envisioned to be attached at the tip of the manipulator proposed by Adejokun et al [35].…”

Medical 3D Printing Using Desktop Inverted Vat Photopolymerization: Background, Clinical Applications, and Challenges

“…The use of 3D printing technology can enable rapid customization of drill guides for individual patients and has been shown to improve accuracy and reduce the risk of mispositioning during surgery [77]. A miniature force sensor using desktop inverted VP 3D printing was developed which can be inserted into living tissue without causing significant damage, unlike current methods for measuring forces in living tissue that are often invasive and can cause tissue damage [109][110][111]. The authors also noted that the use of 3D printing technology can enable rapid and low-cost production of the force sensor, which could make it more accessible for researchers and clinicians.…”