Masoud Kalantari

A New Approach for Modeling Piezoresistive Force Sensors Based on Semiconductive Polymer Composites

Semiconductive polymer composites are used in a wide range of sensors and measurement devices. This paper discusses the development of a model and a new theoretical formulation for predicting piezoresistive behavior in semiconductive polymer composites, including their creep behavior and contact resistance. The relationship between electrical resistance and force applied to the piezoresistive force sensor can be predicted by using the proposed theoretical formulation. In order to verify the proposed formulation, the piezoresistive behavior of Linqstat, a carbon-filled polyethylene, was modeled mathematically. In addition, some experimental tests, such as thermo gravitational analysis and SEM, have been performed on Linqstat to find the volume fraction and size of carbon particles, which are essential for modeling. In addition, on a fabricated force sensor using Linqstat, a force versus resistance curve was obtained experimentally, which verified the validity and reliability of the proposed formulation.

A piezoresistive tactile sensor for tissue characterization during catheter-based cardiac surgery

Currently, most of mitral valve annuloplasty surgeries are performed by using open heart surgery. However, if such operation would be performed by using minimally invasive surgery via catheter‐based techniques (CBT), it offers various advantages for both surgeons and patients.

Design, fabrication, and testing of a piezoresistive hardness sensor in Minimally Invasive Surgery

In the present paper, a novel and reliable tactile sensor is proposed to provide the required tactile feedback to the surgeon allowing the annuloplasty surgery to be performed by Minimally Invasive Surgery (MIS) techniques. The proposed sensor can differentiate between the hardness of different kind of elastomers. The structure of the sensor is very simple and it can easily be microfabricated, and integrated to various surgery devices such as catheters. The paper discusses the design, modeling, and fabrication of the sensor. Several hardness measuring tests are carried out on the sensor and the output is compared to a standard method of hardness measurement by a durometer. Two elastomers with hyperelastic behaviour, representing two different heart tissues were modelled mathematically to verify the sensors output. It is shown that the output of the sensor is reliable.

Viscoelastic Modeling of the Contact Interaction Between a Tactile Sensor and an Atrial Tissue

Modeling and parameter identification of soft tissue are essential in establishing an accurate contact model for tool-tissue interaction, which can be used in the development of high-fidelity surgical instruments. This paper discusses the interaction between a tissue and a tactile sensor in minimally invasive surgery, the focus being a novel technique for robotic-assisted mitral valve repair, in which tactile sensors are used to distinguish between different kinds of tissue by their relative softness. A discrete viscoelastic model is selected to represent the tissue behavior. To populate the model of the tissue with actual data, a set of tissue-testing experiments is designed and implemented on the atrial tissue of a swine heart by analyzing its dynamic response. By means of a genetic algorithm, data of the complex compliance are extracted and used to find the coefficients of the model. Further, a viscoelastic contact model is developed to model the interaction between the tissue and the tactile sensor with annular shape. Finally, the relation among the indentation displacement, the ratio of the radii, and the applied force is established parametrically.

3D Graphical Rendering of Localized Lumps and Arteries for Robotic Assisted MIS

Detection of hard inclusions within soft tissue in robotic assisted minimally invasive surgery (MIS), also referred to as laparoscopic surgery, is of great importance, both in clinical and surgical applications. In clinical applications, surgeons need to detect and precisely identify the location and size of all growths, whether cancerous or benign, that are present within surrounding tissue in order to assess the extent and nature of any future treatment plan. In surgical applications, when any solid matter is being removed, it is important to avoid accidental injury to surrounding tissues and blood vessels since, were this to occur, it could then necessitate the need to resort to open surgery. The present study is aimed at developing a three-dimensional tactile display that provides palpation capability to any surgeon performing robotic assisted MIS. The information is collected from two force sensor/pressure matrices and processed with a new algorithm and graphically rendered. Consequently, the surgeon can determine the presence, location, and the size of any hidden superficial tumor/artery by grasping the target tissue in a quasidynamic way. The developed algorithm is presented, and the results for various configurations of embedded tumor/arteries inside the tissue are compared with those of the finite element analysis. DOI: 10.1115/1.4003736

A piezoresistive based tactile sensor for use in minimally invasive surgery

In the present paper, a novel tactile sensor is proposed for use in minimally invasive surgery to provide surgeons with tactile information. The sensing element of the sensor relies on a piezoresistive material. The proposed sensor measures contact force as well as the relative hardness of soft contact objects. A prototype of the sensor has been built, calibrated, and tested. Experimental test results confirm the ability of the sensor to distinguish between two different elastomeric materials. Such materials resemble two different biological tissues.

Localization of annulus with a tactile sensor

The current paper presents a miniaturized tactile sensor which can be used in robotic-assisted surgery for mitral valve repair. The tactile sensor can localize the position of mitral annulus among the surrounding tissues, leaflet and atrium. The tactile sensor is miniaturized and fabricated on the extremity of a catheter. A test setup is also prepared by using an elastomeric phantom of mitral valve and the results shows that the tactile sensor can distinguish the relative hardness of the annulus from the surrounding tissues.

Modeling and optimal design of an optical MEMS tactile sensor for use in robotically assisted surgery

Currently, Minimally Invasive Surgery (MIS) performs through keyhole incisions using commercially available robotic surgery systems. One of the most famous examples of these robotic surgery systems is the da Vinci surgical system. In the current robotic surgery systems like the da Vinci, surgeons are faced with problems such as lack of tactile feedback during the surgery. Therefore, providing a real-time tactile feedback from interaction between surgical instruments and tissue can help the surgeons to perform MIS more reliably. The present paper proposes an optical tactile sensor to measure the contact force between the bio-tissue and the surgical instrument. A model is proposed for simulating the interaction between a flexible membrane and bio-tissue based on the finite element methods. The tissue is considered as a hyperelastic material with the material properties similar to the heart tissue. The flexible membrane is assumed as a thin layer of silicon which can be microfabricated using the technology of Micro Electro Mechanical Systems (MEMS). The simulation results are used to optimize the geometric design parameters of a proposed MEMS tactile sensor for use in robotic surgical systems to perform MIS.