Sensing Tissue Properties (PCT/US2010/030213)
Inventors: Peng Peng, Rajesh Rajamani, A Serdar Sezen, Arthur G Erdman. Issued April 01, 2010 in us
Flexible tactile sensor for tissue elasticity measurements
Published by (IEEE/ASME Journal of Microelectromechanical Systems)
Authors: Peng Peng, Rajesh Rajamani, Arthur G. Erdman. Published January 01, 2009
This paper presents a novel tactile sensing technique for tissue elasticity measurements. A prototype flexible tactile sensor has been successfully fabricated using polydimethylsiloxane (PDMS) as the structural material. The proposed sensor comprises an array of capacitors with no active elements used. By varying the sizes of sensing membranes within the capacitors, different stiffnesses of sensing diaphragms can be achieved. The elasticity of the targeted object can be thereafter measured based on the relative deflections of the sensing diaphragms. The fabricated sensor has been calibrated by an off-the-shelf polymer durometer hardness selector pack. The results show sensing resolution of 0.1MPa for elasticity measurement and a force sensing resolution as small as 5mN. This flexible tactile sensor can be embedded on the distal portions of various endoscopic instruments for in-vivo tissue elasticity measurements.
Novel MEMS stiffness sensor for force and elasticity measurements
Published by (Sensors & Actuators A: Physical)
Authors: Peng Peng, A Serdar Sezen, Rajash Rajamani, A G Erdman. Published March 01, 2010
This paper presents the design, mathematical model, fabrication and testing of a novel type of in-vivo stiffness sensor. The proposed sensor can measure both stiffness and contact force. The sensing concept utilizes multiple membranes with varying stiffnesses and is particularly designed for integration with minimally invasive surgery (MIS) tools. In order to validate the new sensing concept, MEMS capacitive sensors are fabricated using surface micromachining and each fabricated sensor has a 1mm x 1mm active sensor area. Finally, the sensors are tested by touching polymers of different elastic stiffnesses. The results are promising and confirm both the capability of the sensor for measuring of both force and tissue compliance.
Handheld micro-tactile sensor for elasticity measurement
Published by (IEEE Sensors Journal)
Authors: Peng Peng, Rajesh Rajamani. Published
This paper presents an ultra-low-cost MEMS tactile sensor that can provide elasticity measurement of a variety of target objects. This senor can be integrated on a handheld probe or on minimally invasive surgical tools for in-vivo tissue elasticity measurement. The tactile sensor consists of a pair of contact bumps that have different values of stiffness. Two capacitive force gauges are integrated underneath the bumps. The sensor readout is composed of two channels of capacitance values and the ratio of these capacitance values can be used to calculate the elasticity of target objects. To obtain reliable measurement of capacitance ratios, an estimation algorithm is developed by using a recursive least squares method with adaptive forgetting factors. Experimental characterization of the sensor shows that this tactile sensor provides reliable elasticity measurement of polymer specimens and quickly detects changes in elasticity.
Novel MEMS stiffness sensor for in-vivo tissue stiffness measurements
Published by (31st Annual International Conference of the IEEE Engineering in Medicine and Biology Society)
Authors: Peng Peng, A Serdar Sezen, Rajesh Rajamani, A G Erdman. Published
Flexible tactile sensor for measurements for Young's modulus and shear modulus of elasticity
Published by (Proceeding of Transducers 2011 (The 16th International Conference on Solid-State Sensors, Actuators )
Authors: Peng Peng, Rajesh Rajamani, Xun Yu, Arthur G. Erdman. Published January 01, 2011
This paper presents a tactile sensor capable of in-vivo measurement of Young's modulus and shear modulus of elasticity for soft tissue and other materials. The shear modulus measurement is enabled by using a quad electrode structure in each sensing cell.
Flexible micro-tactile sensor for normal and shear elasticity measurements
Published by (IEEE Transactions on Industrial Electronics)
Authors: Peng Peng, Rajesh Rajamani, Arthur G. Erdman. Published January 01, 2011
This paper presents a tactile sensor capable of measurement of Young’s modulus and shear modulus of elasticity for polymers, soft tissue and other materials. The sensor is built by using polydimethylsiloxane (PDMS) as the structural material. A number of sensing cells of different stiffnesses are used in each sensor. The Young’s modulus of the targeted object can be measured based on the relative deflections of adjacent sensing cells. The shear modulus measurement is enabled by using a quad electrode structure in each sensing cell. Experimental results show sensing resolution of 0.1MPa for Young’s modulus measurement in the range of 0.1MPa to 1MPa, and 0.05MPa for shear modulus measurement ranging from 0.05MPa to 0.2MPa. This flexible tactile sensor can be integrated on the end-effector of robotic arms to achieve tactile sensing feedback. The proposed sensing technology can also be utilized for fast measurement of both Young’s modulus and shear modulus for industrial applications that involves measuring mechanical properties of materials.
Measurement of tension in a string using an array of capacitive force sensors
Published by (IEEE Sensors)
Authors: Peng Peng, Kalpesh Singal, Rajesh Rajamani. Published
The measurement of tension in strings and soft tissues is of critical importance in many applications, including orthopedic surgeries. Various sensors have previously been designed for the measurement of tension, but they all require either attachment of the sensor to the string or the use of an external-inertial reference. This paper presents two new sensors to estimate tension in strings without the need for attaching any devices on the string or a need for an inertial reference. Both sensors employ an array of three capacitive force measurement devices and estimate the tension based on these three readings. Experimental data show that the sensors can measure tension values up to 100 N on a bench-top test rig.
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