FBG-based Force Sensor To Provide Real-time Force Feedback In Laparoscopic Training

BackgroundIn the past few decades,Minimally Invasive Surgery(MIS)has changed the surgical process.Compared with traditional open surgery,MIS has many advantages,such as small incision,less intraoperative bleeding,quick recovery and so on.However,all of these benefits come at the cost of significant difficulties encountered by surgeons during surgery,one of which is the lack of force-tactile feedback.Open surgery allows direct touch of tissue,while minimally invasive surgery uses long instruments inserted through 0.5cm small incisions,lack the sense of touch.The lack of force-tactile feedback during operation prolonged the surgical time and the training period of minimally invasive surgery for novice surgeons to some extent.The acquisition of skills also involves a steep learning curve.In addition,traditional training methods have a high educational cost and excessive clamping force was used during the operation also brings the risk of tissue damage.It is proposed that sensors could be combined with minimally invasive surgical forceps to sense forces during surgery.At present,the force sensors used in minimally invasive surgery mainly include piezoresistive,piezoelectric and capacitive sensors,but they are limited by poor biocompatibility,difficulty in integrating with surgical instruments,electrical safety and so on.In contrast,optical fiber sensor has become a new trend because of its advantages of small size,biocompatibility and anti-electromagnetic interference,and has a good prospect of medical application.In our work,we employ the laparoscopic grasper to provide real-time force feedback to the trainer in the operating process,which can assist in controlling of gripping forces and improve the learning processing of the novices.Objective1.Using an intelligent grasper with a single-core fiber Bragg grating sensor to provide real-time force feedback to assist in controlling of gripping forces and improve the learning processing of the novices.Methods1.Using a laparoscopic forcep with single-core fiber Bragg grating(FBG)sensor to complete the gripping tasks in the laparoscopic training box.Then,setting the gripping threshold and verifying the feasibility of force feedback in laparoscopic training.2.Novices went through three stages:pre-test,training and follow-up,to conduct four weeks training and polt learning curve for the novices.3.In the condition of presence or absence of real-time force feedback,the novices performed the gripping and cutting tasks of living rabbits to verify the learning effect of instantaneous feedback.Results1.The threshold of in vitro gripping was successfully set as 0.73 1N for rough small ball,1.203N for pig small intestine and 0.93 8N for pig heart.2.Without the force feedback,the maximum gripping force and standard deviation of gripping force obtained by the novices were larger than experienced surgeons.The differences was statistically significant(p<0.05).Compare to the novices without force feedback,the gripping force obtained by the novices with force feedback were lower and a better stability.The differences was statistically significant(p<0.05).The maximum gripping force of all tasks in the novices with feedback group was larger than the experienced surgeons group.The differences was statistically significant(p<0.05).Novices gripping level is still not as strong as experienced surgeons,indicating that further training was necessary.3.In laparoscopic training,the learning curve of novice surgeons was successfully mapped.At the 6th training,the maximum grippping force of the novices with feedback group was lower than the threshold value,and then the overall trend was downward.The maximum absolute force of the novices without feedback group in the last training was 0.765 N,which still did not reach the threshold level.The learning curve of novices with feedback group is significantly shorter than that of novices without feedback group.During the follow-up period,there is no significant decline in force learning.4.The results of instantaneous feedback learning in living rabbits showed that compare to without feedback mode,the maximum gripping force,standard deviation of gripping force and force-time product were smaller in feedback mode.The differences was statistically significant(p<0.05).After a learning with feedback,the force value and force-time product in the without force feedback mode all reach,even better than the feedback mode.Conclusion1.A laparoscopic grasper integrated with FBG-based force sensor providing real-time force feedback during laparoscopic training can help to control gripping force,improve gripping stability and significantly shorten the learning curve and training cycle.It may be considered for inclusion in the training of residents and may provide conditions for the development of individualized training courses for trainees.2.Instantaneous force-feedback learning has also playing a positive role in live animals and speeding up learning.There is hope that laboratory-based surgical training will move to live animal studies.