The Study Of Clamping Force Measurement System And Gastric Tissue Tensile Mechanical Properties

For minimally invasive surgery environment providing real-time force feedback signal accurately and better assisting doctors carry out minimally invasive surgery, the paper has designed a virtual instrument testing system for forceps clamping force, to explore a kind of clamping force detection scheme. According to the tested clamping force value, the paper has conducted one-dimensional tensile mechanical experiment of the pig stomach tissue, tested the mechanical response characteristics of the soft tissue, aims to better understand of the mechanical properties of soft tissues, to provides the experimental data for the study of minimally invasive devices and soft tissues interface interaction mechanism.By referring to related literature at home and abroad, the paper has designed a virtual instrument testing system for forceps clamping force. The system adopted the Flexi Force sensor to acquire the initial signal. According to the principle and characteristic parameters of the sensor, the special signal conditioning module were designed, including the power circuit (Based on the chip LM27313), the bridge circuit, the instrumentation amplifier circuit (Based on the chip INA128) and the second order voltage-controlled low-pass filter circuit (Based on the chip OP07CP), to process and transfer the analog voltage signal. Data acquisition board (USB-4704 from ADVANTECH company) was used to sample signal, complete A/D conversion and communicate with the upper machine. Based on graphical development environment (LabVIEW), the paper have completed the software program, achieving the testing control function of the software, including sampling parameters setting, data reading and processing, image real-time displaying and data storing. The calibrated system was used to test the force value when the forceps clamping gastric tissue. The force value was14.2±0.05N, conformed to the requirements of the test.On the basis of the clamping force value and the micro-control electronic universal material testing machine (HY0580), the paper have designed the one-dimensional tensile mechanical response experiment of gastric soft tissues, including loading-unloading, stress relaxation, creep and tensile fracture experiment. The experimental data was averaged, normalized, F-tested, t-tested. Comparing the analysis of the experimental data, we expounded the mechanical response differences, illustrating the viscoelasticity, nonlinearity, hysteresis and anisotropy of gastric stomach tissues. From the differences of the structure and function of the gastric stomach, we explained the mechanical response differences.