A micro-tactile sensor for in situ tissue characterization in minimally invasive surgery M. A. Qasaimeh & S. Sokhanvar & J. Dargahi & M. Kahrizi Published online: 24 June 2008 # Springer Science + Business Media, LLC 2008 Abstract This study presents and characterizes a micro- tactile sensor that can be integrated within MIS graspers. The sensor is capable of measuring contact forces and characterizing softness. The grasping forces are distributed normally, though in some cases concentrated loads also appear at the contact surfaces. In the latter case, the position of the concentric load can also be determined. This enables the sensor to detect hidden anatomical features such as embedded lumps or arteries. The microfabricated piezo- electric-based sensor was modeled both analytically and numerically. In a parametric study the influence of param- eters such as length, width, and thickness of the sensor was studied using a finite element model. The sensor was microfabricated and tested using elastomeric samples. There is a good conformity between the experimental and theoretical results. Keywords Micro-tactile sensor . Tissue characterization . Endoscopic graspers . Minimally Invasive Surgery (MIS) 1 Introduction Useful information is supplied by the sensory interactions between humans and the surrounding environment during different manual tasks. Thanks to subcutaneous mechano- receptor cells, our sense of touch is capable of determining the shape, size, softness and temperature of objects. By using our sense of touch, we can perform many precise and delicate tasks with our hands. Were we deprived of this feeling, the story would be complicated. Our ability would be limited and we would have poor tactile precision (Dargahi and Najarian 2004). Recently, many researchers have begun investigating tactile sensing in a variety of applications including manipulators, virtual reality, and especially medical treatment (Howe et al. 1995). In the medical field, minimally invasive surgery (MIS) has been the focus of much of the attention. MIS procedures have been widely accepted because of their many benefits. Many research centers and companies have focused on the development of MIS as a replacement for many types of traditional open surgeries. Despite the many advantages of MIS, the lack of the sense of touch has created a serious challenge for surgeons and has reduced the safety and efficiency of surgical operations. That is because soft tissue can be properly inspected and assessed by evaluating its softness, viscosity, and elasticity properties (Melzer et al. 1994; Rebello 2004). One of the very important evaluation procedures during surgery is the palpation of tissues and organs. It is an essential step for any surgical process (Howe et al. 1995; Howe and Matsuoka 1999; Webster 1988; Ottermo et al. 2004; Peine et al. 1994; Nahas et al. 2002; Kurodaa et al. 2005). During open surgeries, a surgeon can palpate tissues to examine the size, consistency, texture, location, and tenderness of an organ. However, this tactile information Biomed Microdevices (2008) 10:823–837 DOI 10.1007/s10544-008-9197-0 M. A. Qasaimeh (*) : S. Sokhanvar : J. Dargahi Tactile Sensing and Medical Robotics Laboratory, Department of Mechanical and Industrial Engineering, Concordia University, 1455 De Maisonneuve Blvd. West, Montreal, QC H3G 1M8, Canada e-mail: mohammad.qasaimeh@mail.mcgill.ca M. A. Qasaimeh : M. Kahrizi MEMS and NanoDevices Laboratory, Department of Electrical and Computer Engineering, Concordia University, 1455 De Maisonneuve Blvd. West, Montreal, QC H3G 1M8, Canada