By Soham NandiReviewed by Frances BriggsJun 30 2025Researchers have developed a soft robotic sleeve for colonoscopes that actively monitors and redistributes pressure in real time, significantly improving patient safety and comfort without disrupting clinical procedures.
Image Credit: Inside Creative House/Shutterstock.com
A recent study published in Nature introduced a soft robotic add-on for colonoscopes, designed to improve patient safety and procedural comfort.
The device features real-time 3D shape sensing, continuous force monitoring, and pressure-redistributing actuators, which aim to minimize tissue damage during colonoscopy. It integrates smoothly into current clinical workflows so no procedural changes are required, and has been validated through ex vivo and in vivo laboratory testing.
Why It Matters
Colonoscopy remains the most reliable method for detecting colorectal cancer. However, current systems lack real-time force feedback and safety mechanisms, which can often lead to patient discomfort and potential complications.
Alternatives have been introduced as a solution, such as capsule endoscopes and magnetically guided systems, but they tend to fall short on control, cost-efficiency, and therapeutic use. Further efforts in soft robotics have shown promise, but typically don't offer the compatibility or precision needed for clinical adoption.
The add-on revealed in this study addresses those gaps by combining force monitoring with shape detection through optical sensors. When potentially harmful pressure is detected, soft actuators redistribute the force automatically.
Tested across a range of settings, from the lab to live animal models, the add-on has shown improved safety without complicating the process for medical professionals.
Design and Testing Procedures
The sleeve includes five U-shaped optical waveguides, each with a 750 µm2 cross-section made from UV-curable Norland Optical Adhesive (NOA 65) for flexibility. Oval pneumatic actuators (30×8 mm) provide controlled expansion without causing disruptions to the colonoscope sensor.
The researchers used optical circuits with 650 nm LEDs and phototransistors for real-time sensing, and fine-tuned the signal bandwidth with potentiometers.
The add-on was fabricated using a layer-by-layer approach with computer-numeric control machined aluminum molds. The bending and contact layers were formed with Ecoflex 00-30, while NOA 65 was used to create optical cores, and the design's structural integrity was achieved by using wrapped seams and Dragon Skin 30 injections.
Contact force amplifying indenters are another important aspect of the design. These indentors use the waveguides' multi-modal nature, which allows a single signal to detect both bending and force by selectively amplifying different loss modes based on the setup.
To calibrate the add-on, the sleeve was bent to a curvature of 15 m-1 in twelve 30 ° directions, later simplified to four key orientations for operational efficiency (60°, 120°, 240°, 300°). An Instron machine applied up to six newtons of force, demonstrating consistent WG signal loss patterns during contact.
Characterization confirmed that the actuators expanded by 12.7-13 mm under 25 kPa pressure with a 3-second return time, performing well in both straight and curved positions.
Download your PDF copy now!
Validation and Real-World Testing
In vivo trials involved two 30 kg Yorkshire pigs under approved anesthesia and continuous veterinary monitoring. The sleeve maintained full functionality during live procedures, showing no adverse effects on the animals.
In terms of integration, the device worked seamlessly with commercial endoscopes (23 mm outer diameter). The waveguides accurately reconstructed 3D shapes (8.51 % curvature error, 9.67 % orientation error) and measured force with 3.38 % error. The system also successfully distinguished between bending and contact forces and activated pressure redistribution at 5 N thresholds.
In vitro tests showed that the actuators could reduce localized pressure by 83 %. Ex vivo trials using bovine colon and seven users, ranging from novices to experts, were conducted to demonstrate the add-on's compatibility with user workflow.
Average navigation time dropped from 70.7 to 47.1 seconds with the add-on, with no significant increase in perceived workload. When using the sleeve, experts completed procedures 7.3 seconds faster than with a regular colonoscope.
In vivo trials showed minimal impact on procedure time (a difference of just 3.6 seconds) and no disruption to vital signs (heart rate changed by less than 0.36 %, oxygenation levels by less than 0.19 %). The sleeve’s actuators activated about 4.2 times per trial in response to excessive force.
The portable control box enabled quick, plug-and-play setup. The device's optical sensors functioned reliably through more than ten sterilization cycles, and actuators consistently performed at expected levels.
Final Thoughts
This soft robotic sleeve adds a layer of safety and precision to standard colonoscopy without altering existing practices. Its disposable design reduces infection risk, while built-in sensors and actuators monitor and respond to excessive pressure in real-time. Backed by comprehensive testing, this solution offers a practical step forward in improving patient care during colorectal cancer screening.
Journal Reference
Bono, V. D. et al., (2025). A soft robotic “Add-on” for colonoscopy: increasing safety and comfort through force monitoring. Npj Robotics, 3(1). DOI:10.1038/s44182-025-00028-1. https://www.nature.com/articles/s44182-025-00028-1
Disclaimer: The views expressed here are those of the author expressed in their private capacity and do not necessarily represent the views of AZoM.com Limited T/A AZoNetwork the owner and operator of this website. This disclaimer forms part of the Terms and conditions of use of this website.