title: Force model for laparoscopic graspers: implications for virtual simulator design.
abstract: BACKGROUND
  Laparoscopic graspers limit haptic perception, which in turn leads to tissue damage. Using virtual simulators to train surgeons in handling these instruments would ensure safer grasp. The design of a laparoscopic virtual simulator with force feedback depends on effective implementation of the grasper force model.
  
  
  OBJECTIVE
  To develop a laparoscopic grasper tip force model theoretically from grasper mechanics and validate the same experimentally during laparoscopic pinching.
  
  
  METHODS
  We developed a force model for double and single jaw action graspers using grasper mechanics. For experimental validation, the handle angle and the forces at the tip and the handle of the instrumented graspers during laparoscopic pinching of porcine abdominal tissues were measured. The intra-class correlation coefficient (ICC) between experimental and calculated tip force was calculated.
  
  
  RESULTS
  Excellent ICC (ICC ≥0.8, p<.001) between calculated and experimental tip force was obtained for both graspers for all grasped tissues. Mean absolute forces for all trials while using double and single jaw action graspers were ((FTc= 1.7N, FTe= 1.8N) and (FTc= 2.2N, FTe= 2.8N)) for gall bladder, ((FTc= 3.4N, FTe= 4.4N) and (FTc= 3.3N, FTe= 3.4N)) for liver and ((FTc= 4.2N, FTe= 4.5N) and (FTc= 2.3N, FTe= 2.6N)) for spleen, respectively.
  
  
  CONCLUSIONS
  The proposed model may be used for the design of laparoscopic pinching action in a virtual simulator with force feedback and also for better ergonomic design of laparoscopic graspers.
authors.affiliation: a Department of Bioengineering , Christian Medical College Vellore , Tamil Nadu , India.|b Department of Biotechnology , Indian Institute of Technology Madras , Tamil Nadu , India.
authors.forename: K
authors.initials: K
authors.lastname: Susmitha Wils
authors.affiliation: a Department of Bioengineering , Christian Medical College Vellore , Tamil Nadu , India.
authors.forename: Suresh R
authors.initials: SR
authors.lastname: Devasahayam
authors.affiliation: c Department of Applied Mechanics , Indian Institute of Technology Madras , Tamil Nadu , India.
authors.forename: M
authors.initials: M
authors.lastname: Manivannan
authors.affiliation: d Medical Sciences Group, University of Pelita Harapan Medical Sciences , Tangerang , Indonesia.
authors.forename: George
authors.initials: G
authors.lastname: Mathew
mesh_terms: D000005:Abdomen / Q000601:surgery*; D000818:Animals; D003194:Computer-Assisted Instruction; D004867:Equipment Design; D006804:Ergonomics; D005246:Feedback; D010535:Laparoscopy / Q000295:instrumentation / Q000379:methods*; D008297:Male; D013552:Swine; D014584:User-Computer Interface
keywords: Laparoscopic graspers; force model; force transmission; laparoscopic pinching; virtual simulator