A Soft Robot for Peripheral Lung Cancer Diagnosis and Therapy

A fabrication strategy for millimeter-scale, self-sensing soft-rigid hybrid robots

Soft robots typically involve manual assembly of core hardware components like actuators, sensors, and controllers. This increases fabrication time and reduces consistency, especially in small-scale soft robots. We present a scalable monolithic fabrication method for millimeter-scale soft-rigid hybrid robots, simplifying the integration of core hardware components. Actuation is provided by soft-foldable polytetrafluoroethylene film-based actuators powered by ionic fluid injection. The desired motion is encoded by integrating a mechanical controller, comprised of rigid-flexible materials. The robot's motion can be self-sensed using an ionic resistive sensor by detecting electrical resistance changes across its body. Our approach is demonstrated by fabricating three distinct soft-rigid hybrid robotic modules, each with unique degrees of freedom: translational, bending, and roto-translational motions. These modules connect to form a soft-rigid hybrid continuum robot with real-time shape-sensing capabilities. We showcase the robot's capabilities by performing object pick-and-place, needle steering and tissue puncturing, and optical fiber steering tasks.

Design and navigation method of a soft robot for single-port transvesical radical prostatectomy

PURPOSE

Currently, the rigid instruments used for laparoscopic radical resection of prostate cancer not only have the risk of damage to tissues, blood vessels, and nerves, but their limited freedom will also cause surgical blind areas. Soft robots are expected to solve these issues due to inherent flexibility, compliance, and safe interaction with tissues and organs. In addition, to achieve high surgical accuracy and provide precise guidance for surgeons, the navigation method should be studied for the soft robot.

METHODS

A soft robot system for single-port transvesical radical prostatectomy (STRP) is developed, and a navigation method combining fiber Bragg gratings and electromagnetic tracking is proposed for the soft robot. To validate the soft robot design and the effectiveness of the navigation method, different groups of experiments are conducted.

RESULTS

The proposed navigation method can achieve accurate location and shape sensing of the soft manipulator. The experiments show that the maximum tip sensing error is 2.691 mm, which is 5.38 % of the robot length for static configurations, and that the average tip sensing error is 1.966 mm, which corresponds to 3.93 % of the robot length for dynamic scenarios. Additionally, phantom tests demonstrate that the designed soft robot can enter the prostate through navigation guidance in a master-slave control mode and cover the entire prostate space.

CONCLUSIONS

The designed soft robot system, due to its soft structure, good flexibility, and accurate navigation, is expected to improve surgical safety and precision, thereby exhibiting significant potential for STRP.

PneumaOCT: Pneumatic optical coherence tomography endoscopy for targeted distortion-free imaging in tortuous and narrow internal lumens

The complex anatomy of internal luminal organs, like bronchioles, poses challenges for endoscopic optical coherence tomography (OCT). These challenges include limited steerability for targeted imaging and nonuniform rotation distortion (NURD) with proximal scanning. Using rotary micromotors for distal scanning could address NURD but raises concerns about electrical safety and costs. We present pneumaOCT, the first pneumatic OCT endoscope, comprising a steerable catheter with a soft pneumatic actuator and an imaging probe with a miniature pneumatic turbine. With a diameter of 2.8 mm, pneumaOCT allows for a bending angle of up to 237°, facilitating navigation through narrow turns. The pneumatic turbine enables adjustable imaging speeds from 51 to 446 revolutions per second. We demonstrate the pneumaOCT in vivo imaging of mouse esophagus and colon, as well as targeted and distortion-free imaging of peripheral bronchioles in a bronchial phantom and a porcine lung. This advancement substantially improves endoscopic OCT for navigational imaging in curved and narrow lumens.

Toward "S"-Shaped 3D-Printed Soft Robotic Guidewires for Pediatric Patent Ductus Arteriosus Endovascular Interventions

Patent Ductus Arteriosus (PDA) is a heart condition in which the ductus arteriosus-a blood vessel connecting the pulmonary artery to the aorta in a fetus-fails to undergo closure after birth. A PDA can be an important factor in neonates born with severe congenital heart disease (CHD) or born prematurely. With the advent of new intravascular stent technologies, treatments based on ductus arteriosus stenting can now be completed in many cases; however, difficulties remain in accessing the ductus arteriosus in small babies successfully using current guidewire-catheter systems. Recent developments for soft robotic endovascular instruments that leverage control schemes hold distinctive potential for addressing these access challenges, but such technologies are not yet at the sizes required for navigating neonatal vasculature safely and efficiently. In an effort to meet this clinical need, this work presents an approach for 3D printing 1.5 French (Fr) soft robotic guidewires that transition from straight to "S"-shaped configurations under the application of fluidic (e.g., pneumatic or hydraulic) loading. Two distinct dual-opposing segmented soft actuators, including a symmetric and asymmetric system design (both with heights of 2.5 mm), were 3D printed onto 1.1 Fr capillaries in 35-60 minutes via "Two-Photon Direct Laser Writing (DLW)". Experimental results revealed that both designs not only withstood pressures of up to 550 kPa, but also exhibited increased opposing bending deformations-corresponding to decreased radii of curvature-with increasing applied pressure. In combination, this study serves as a critical foundation for next-generation fluidically actuated soft robotic guidewire-catheter systems for PDA interventions.

An Approach for 3D Microprinting Soft Robotic Surgical Tools at 1.5 French Length Scales for Endovascular Interventions

A wide range of endovascular interventions rely on surgical tools such as guidewire-catheter systems for navigating through blood vessels to, for example, deliver embolic materials, stents, and/or therapeutic agents to target sites as well as biopsy tools (e.g., forceps and punch needles) for medical diagnostics. In response to the difficulties in maneuvering such endovascular instruments safely and effectively to access intended sites in the body, researchers have developed an array of soft robotic surgical tools that harness fluidic (e.g., pneumatic or hydraulic) actuation schemes to support on-demand steering and control. Despite considerable progress, scaling these tools down to the sizes required for medical procedures such as cerebral aneurysm treatment and liver chemoembolization have been hindered by manufacturing-induced constraints. To provide a pathway to overcome these miniaturization challenges, this work presents a novel additive manufacturing strategy for 3D microprinting integrated soft actuators directly atop multilumen microfluidic tubing via "Two-Photon Direct Laser Writing (DLW)". As an exemplar, a two-actuator tip was 3D printed onto custom dual-lumen tubing-resulting in a system akin to a 1.5 French (Fr) guidewire with a steerable tip. Experimental results revealed independent actuator control via the discretized lumens, with tip bending of approximately 60° under input pressures of 130 kPa via hydraulic actuation. These results suggest that the presented strategy could be extended to achieve new classes of fluidically actuated soft robotic surgical tools at unprecedented length scales for emerging applications in minimally invasive surgery.

Design Optimization of a Hybrid-Driven Soft Surgical Robot with Biomimetic Constraints

The current study investigated the geometry optimization of a hybrid-driven (based on the combination of air pressure and tendon tension) soft robot for use in robot-assisted intra-bronchial intervention. Soft robots, made from compliant materials, have gained popularity for use in surgical interventions due to their dexterity and safety. The current study aimed to design a catheter-like soft robot with an improved performance by minimizing radial expansion during inflation and increasing the force exerted on targeted tissues through geometry optimization. To do so, a finite element analysis (FEA) was employed to optimize the soft robot's geometry, considering a multi-objective goal function that incorporated factors such as chamber pressures, tendon tensions, and the cross-sectional area. To accomplish this, a cylindrical soft robot with three air chambers, three tendons, and a central working channel was considered. Then, the dimensions of the soft robot, including the length of the air chambers, the diameter of the air chambers, and the offsets of the air chambers and tendon routes, were optimized to minimize the goal function in an in-plane bending scenario. To accurately simulate the behavior of the soft robot, Ecoflex 00-50 samples were tested based on ISO 7743, and a hyperplastic model was fitted on the compression test data. The FEA simulations were performed using the response surface optimization (RSO) module in ANSYS software, which iteratively explored the design space based on defined objectives and constraints. Using RSO, 45 points of experiments were generated based on the geometrical and loading constraints. During the simulations, tendon force was applied to the tip of the soft robot, while simultaneously, air pressure was applied inside the chamber. Following the optimization of the geometry, a prototype of the soft robot with the optimized values was fabricated and tested in a phantom model, mimicking simulated surgical conditions. The decreased actuation effort and radial expansion of the soft robot resulting from the optimization process have the potential to increase the performance of the manipulator. This advancement led to improved control over the soft robot while additionally minimizing unnecessary cross-sectional expansion. The study demonstrates the effectiveness of the optimization methodology for refining the soft robot's design and highlights its potential for enhancing surgical interventions.

AI co-pilot bronchoscope robot

The unequal distribution of medical resources and scarcity of experienced practitioners confine access to bronchoscopy primarily to well-equipped hospitals in developed regions, contributing to the unavailability of bronchoscopic services in underdeveloped areas. Here, we present an artificial intelligence (AI) co-pilot bronchoscope robot that empowers novice doctors to conduct lung examinations as safely and adeptly as experienced colleagues. The system features a user-friendly, plug-and-play catheter, devised for robot-assisted steering, facilitating access to bronchi beyond the fifth generation in average adult patients. Drawing upon historical bronchoscopic videos and expert imitation, our AI-human shared control algorithm enables novice doctors to achieve safe steering in the lung, mitigating misoperations. Both in vitro and in vivo results underscore that our system equips novice doctors with the skills to perform lung examinations as expertly as seasoned practitioners. This study offers innovative strategies to address the pressing issue of medical resource disparities through AI assistance.

A 3D-MICROPRINTED COAXIAL NOZZLE FOR FABRICATING LONG, FLEXIBLE MICROFLUIDIC TUBING

A variety of emerging applications, particularly those in medical and soft robotics fields, are predicated on the ability to fabricate long, flexible meso/microfluidic tubing with high customization. To address this need, here we present a hybrid additive manufacturing (or "three-dimensional (3D) printing") strategy that involves three key steps: (i) using the "Vat Photopolymerization (VPP) technique, "Liquid-Crystal Display (LCD)" 3D printing to print a bulk microfluidic device with three inlets and three concentric outlets; (ii) using "Two-Photon Direct Laser Writing (DLW)" to 3D microprint a coaxial nozzle directly atop the concentric outlets of the bulk microdevice, and then (iii) extruding paraffin oil and a liquid-phase photocurable resin through the coaxial nozzle and into a polydimethylsiloxane (PDMS) channel for UV exposure, ultimately producing the desired tubing. In addition to fabricating the resulting tubing-composed of polymerized photomaterial-at arbitrary lengths (e.g., > 10 cm), the distinct input pressures can be adjusted to tune the inner diameter (ID) and outer diameter (OD) of the fabricated tubing. For example, experimental results revealed that increasing the driving pressure of the liquid-phase photomaterial from 50 kPa to 100 kPa led to fluidic tubing with IDs and ODs of 291±99 μm and 546±76 μm up to 741±31 μm and 888±39 μm, respectively. Furthermore, preliminary results for DLW-printing a microfluidic "M" structure directly atop the tubing suggest that the tubing could be used for "ex situ DLW (esDLW)" fabrication, which would further enhance the utility of the tubing.

A multifunctional soft robot for cardiac interventions

In minimally invasive endovascular procedures, surgeons rely on catheters with low dexterity and high aspect ratios to reach an anatomical target. However, the environment inside the beating heart presents a combination of challenges unique to few anatomic locations, making it difficult for interventional tools to maneuver dexterously and apply substantial forces on an intracardiac target. We demonstrate a millimeter-scale soft robotic platform that can deploy and self-stabilize at the entrance to the heart, and guide existing interventional tools toward a target site. In two exemplar intracardiac procedures within the right atrium, the robotic platform provides enough dexterity to reach multiple anatomical targets, enough stability to maintain constant contact on motile targets, and enough mechanical leverage to generate newton-level forces. Because the device addresses ongoing challenges in minimally invasive intracardiac intervention, it may enable the further development of catheter-based interventions.

Personalized magnetic tentacles for targeted photothermal cancer therapy in peripheral lungs

Lung cancer remains one of the most life-threatening diseases and is currently managed through invasive approaches such as surgery, chemo- or radiotherapy. In this work, we introduce a novel method for the targeted delivery of a therapeutic laser for the treatment of tumors in peripheral areas of the lungs. The approach uses a 2.4 mm diameter, ultra-soft, patient-specific magnetic catheter delivered from the end of a standard bronchoscope to reach the periphery of the lungs. Integrated shape sensing facilitates supervised autonomous full-shape control for precise navigation into the sub-segmental bronchi, and an embedded laser fiber allows for treatment via localized energy delivery. We report the complete navigation of eight primary lumina in the bronchi of an anatomically accurate phantom (developed from computed tomography (CT) data) and successful laser delivery for photothermal ablation. We further evaluate the approach in three diverse branches of excised cadaveric lungs, showing a mean improvement in navigation depth of 37% with less tissue displacement when compared to a standard semi-rigid catheter and navigation depth repeatability across all tests of <1 mm.

A Millimeter-Scale Soft Robot for Tissue Biopsy Procedures

While interest in soft robotics as surgical tools has grown due to their inherently safe interactions with the body, their feasibility is limited in the amount of force that can be transmitted during procedures. This is especially apparent in minimally invasive procedures where millimeter-scale devices are necessary for reaching the desired surgical site, such as in interventional bronchoscopy. To leverage the benefits of soft robotics in minimally invasive surgery, a soft robot with integrated tip steering, stabilization, and needle deployment capabilities is proposed for lung tissue biopsy procedures. Design, fabrication, and modeling of the force transmission of this soft robotic platform allows for integration into a system with a diameter of 3.5 mm. Characterizations of the soft robot are performed to analyze bending angle, force transmission, and expansion during needle deployment. In-vitro experiments of both the needle deployment mechanism and fully integrated soft robot validate the proposed workflow and capabilities in a simulated surgical setting.

Multicomponent and multifunctional integrated miniature soft robots

Miniature soft robots with elaborate structures and programmable physical properties could conduct micromanipulation with high precision as well as access confined and tortuous spaces, which promise benefits in medical tasks and environmental monitoring. To improve the functionalities and adaptability of miniature soft robots, a variety of integrated design and fabrication strategies have been proposed for the development of miniaturized soft robotic systems integrated with multicomponents and multifunctionalities. Combining the latest advancement in fabrication technologies, intelligent materials and active control methods enable these integrated robotic systems to adapt to increasingly complex application scenarios including precision medicine, intelligent electronics, and environmental and proprioceptive sensing. Herein, this review delivers an overview of various integration strategies applicable for miniature soft robotic systems, including semiconductor and microelectronic techniques, modular assembly based on self-healing and welding, modular assembly based on bonding agents, laser machining techniques, template assisted methods with modular material design, and 3D printing techniques. Emerging applications of the integrated miniature soft robots and perspectives for the future design of small-scale intelligent robots are discussed.