Smart laparoscopic grasper integrated with fiber Bragg grating based tactile sensor for real-time force feedback

An intelligent grasper to provide real-time force feedback to shorten the learning curve in laparoscopic training

BACKGROUND

A lack of force feedback in laparoscopic surgery often leads to a steep learning curve to the novices and traditional training system equipped with force feedback need a high educational cost. This study aimed to use a laparoscopic grasper providing force feedback in laparoscopic training which can assist in controlling of gripping forces and improve the learning processing of the novices.

METHODS

Firstly, we conducted a pre-experiment to verify the role of force feedback in gripping operations and establish the safe gripping force threshold for the tasks. Following this, we proceeded with a four-week training program. Unlike the novices without feedback (Group A2), the novices receiving feedback (Group B2) underwent training that included force feedback. Finally, we completed a follow-up period without providing force feedback to assess the training effect under different conditions. Real-time force parameters were recorded and compared.

RESULTS

In the pre-experiment, we set the gripping force threshold for the tasks based on the experienced surgeons' performance. This is reasonable as the experienced surgeons have obtained adequate skill of handling grasper. The thresholds for task 1, 2, and 3 were set as 0.731 N, 1.203 N and 0.938 N, respectively. With force feedback, the gripping force applied by the novices with feedback (Group B1) was lower than that of the novices without feedback (Group A1) (p < 0.005). During the training period, the Group B2 takes 6 trails to achieve gripping force of 0.635 N, which is lower than the threshold line, whereas the Group A2 needs 11 trails, meaning that the learning curve of Group B2 was significantly shorter than that of Group A2. Additionally, during the follow-up period, there was no significant decline in force learning, and Group B2 demonstrated better control of gripping operations. The training with force feedback received positive evaluations.

CONCLUSION

Our study shows that using a grasper providing force feedback in laparoscopic training can help to control the gripping force and shorten the learning curve. It is anticipated that the laparoscopic grasper equipped with FBG sensor is promising to provide force feedback during laparoscopic training, which ultimately shows great potential in laparoscopic surgery.

Ultrasensitive measurement of tactile force based on a PDMS-embedded microfiber Mach-Zehnder interferometer

This study investigates the utilization of an in-fiber interferometer embedded in polydimethylsiloxane (PDMS) to develop a highly sensitive tactile sensor. The tapered mode-field mismatch structure is more conducive to stimulating strong high order modes to promote the sensitivity of the sensor. Experimental investigations are conducted to study the sensing performance of the sensor, resulting in a sensitivity of 23.636 nm/N and a detection limit of 0.746 mN. The experiments demonstrate that employing fast Fourier transform (FFT) and inverse FFT (IFFT) methods to filter weak high order modes significantly improves the repeatability of the sensor, resulting in a repeatability error of less than 1%.

Three-dimensional force detection and decoupling of a fiber grating sensor for a humanoid prosthetic hand

A fiber Bragg grating (FBG) based three-dimensional (3D) force sensor for a humanoid prosthetic hand is designed, which can precisely detect 3D force and compensate for ambient temperature. FBG was encapsulated in polydimethylsiloxane (PDMS) for force sensitization and immobilization, and the structural parameters of the sensor were optimized by using finite element simulation, so that its sensitivity to 3D force is enhanced. In the meantime, the calibration experiments for normal force fZ, shear force fX/fY, and temperature were conducted, and the 3D force data were decoupled using the least square (LS) and backpropagation (BP) neural networks decoupling methods, so that an overall decoupling error is 0.038. The results show that the sensor has a simple structure, high sensitivity, high linearity, good creep resistance, and rapid decoupling, providing a successful design for the 3D force detection of a humanoid prosthetic hand.

PDMS-assisted GaN optical hardness sensors

In this Letter, an optical hardness sensor is fabricated based on a GaN-based device combined with finger-shaped PDMS. The chip-scale 1 mm × 1 mm GaN-based device is monolithically integrated with a light emitter and receiver responsible for light emission and photodetection, respectively. The micropatterned PDMS layer can effectively convert the hardness information of the measured object into an optical change detected by the receiver. Verified by experiment measurements, the sensor exhibits a linear response in a hardness range of 1-84 HA, a sensitivity of 0.24 µA/HA, a fast response time of 1.2 ms, and a high degree of repeatability and stability. The optical sensor has the characteristics of tiny size, high compactness, inexpensive fabrication cost, wide measurement range, and high stability, making it suitable for hardness measurement in practical applications.

Progress in Control-Actuation Robotic System for Gastrointestinal NOTES Development

Purpose

Natural orifice transluminal endoscopic surgery (NOTES) is a minimally invasive surgical procedure that reduces patient trauma, infection probability, and rehabilitation time. This paper reviews the progress made in the control-actuation robotic systems for gastrointestinal NOTES development. Material and Methods. A survey on both existing and state-of-the-art control-actuation robotic systems for gastrointestinal NOTES was conducted in December 2021.

Results

Nine control-actuation robotic systems for gastrointestinal NOTES were identified. The structures and specifications of these robotic systems were reported. The technical parameters were also discussed. Special attention was directed to systems using a control-actuation structure and tendon-driven mechanism. The control-actuation robotic systems typically deploy a control-actuation structure and tendon-driven mechanism. Control-actuation robotic systems for gastrointestinal NOTES show great ability to improve operational accuracy and flexibility and flatten the learning curve of procedures. These characteristics suggest that the use of control-actuation robotic systems is worth exploring in future development.

Highly sensitive soft optical fiber tactile sensor

A soft highly sensitive tactile sensor based on an in-fiber interferometer embedded in polydimethylsiloxane (PDMS) structure is studied. Theoretical simulation obtains that the high order sensing modes and PDMS can improve the sensitivity. Experiments show that different order sensing modes, derived by fast Fourier transform (FFT) and inverse FFT methods, present different sensing performance. Corresponding to high order mode, 1.3593 nm/kPa sensitivity and 37 Pa (0.015 N) detection limit is obtained. Meanwhile, it also shows very good stability, reproducibility, and response time. This study not only demonstrates a tactile sensor with high sensitivity but also provides a novel sensing modes analysis method.

Stiffness Assessment and Lump Detection in Minimally Invasive Surgery Using In-House Developed Smart Laparoscopic Forceps

Minimally invasive surgery (MIS) incorporates surgical instruments through small incisions to perform procedures. Despite the potential advantages of MIS, the lack of tactile sensation and haptic feedback due to the indirect contact between the surgeon’s hands and the tissues restricts sensing the strength of applied forces or obtaining information about the biomechanical properties of tissues under operation. Accordingly, there is a crucial need for intelligent systems to provide an artificial tactile sensation to MIS surgeons and trainees. This study evaluates the potential of our proposed real-time grasping forces and deformation angles feedback to assist surgeons in detecting tissues’ stiffness. A prototype was developed using a standard laparoscopic grasper integrated with a force-sensitive resistor on one grasping jaw and a tunneling magneto-resistor on the handle’s joint to measure the grasping force and the jaws’ opening angle, respectively. The sensors’ data are analyzed using a microcontroller, and the output is displayed on a small screen and saved to a log file. This integrated system was evaluated by running multiple grasp-release tests using both elastomeric and biological tissue samples, in which the average force-to-angle-change ratio precisely resembled the stiffness of grasped samples. Another feature is the detection of hidden lumps by palpation, looking for sudden variations in the measured stiffness. In experiments, the real-time grasping feedback helped enhance the surgeons’ sorting accuracy of testing models based on their stiffness. The developed tool demonstrated a great potential for low-cost tactile sensing in MIS procedures, with room for future improvements. Significance: The proposed method can contribute to MIS by assessing stiffness, detecting hidden lumps, preventing excessive forces during operation, and reducing the learning curve for trainees.