Shock Wave Detection System Based On Wearable Sensor

Shock wave is a type of triangular pulse wave with characteristics such as rapid change,high amplitude,and no periodicity.Shock wave can cause sharp changes in physical properties such as pressure,temperature,and density in the surrounding environment,which is extremely dangerous and destructive.When shock wave acts on the human body,it can cause varying degrees of damage to the skin.Therefore,a wearable shock wave pressure sensor that can be fixed on the surface of the skin is needed to evaluate the degree of damage caused by shock wave to the skin.With the development of MEMS technology,the dynamic characteristics of piezoresistive pressure sensors have been greatly improved and piezoresistive pressure sensors are widely used in shock wave pressure measurement.Therefore,this thesis combines a PDMS flexible substrate with a slot structure and a MEMS piezoresistive pressure sensor to design a shock wave pressure sensor system,and studies and analyzes the pressure distribution on the skin surface under the action of shock wave.The main research content includes:Firstly,From the perspective of minimizing the attenuation of shock wave pressure,a flexible substrate structure to fixed MEMS pressure sensor has been determined through simulation method.Based on Autodyn finite element analysis,the influence of PDMS flexible substrate with different groove and convex structures on the attenuation of shock wave on the surface of human skin was studied,and it was determined to embed a MEMS piezoresistive pressure sensor to the optimal structural arrangement of a PDMS flexible substrate with 8 × 8 ×1.1 mm square groove.The balloon explosion impact detection experiment was conducted on it,and the results showed that the flexible shock wave pressure sensor has good dynamic characteristics and can be used for impact pressure detection.Then,this thesis has simulated and analyzed the response characteristics of flexible shock wave pressure sensor under different shock waves.The simulation results show that the smaller the pressure of the shock source,the higher the shock source,and the greater the displacement of the shock source deviating from the vertical line of the sensor,the smaller the shock wave pressure detected on the sensor surface.The PDMS flexible substrate with a groove structure has a smaller attenuation of the shock wave pressure.In addition,adding a square hole array design on its surface can further increase adhesion to the skin and reduce pressure attenuation.The larger and deeper the square hole size,the smaller the attenuation of shock wave pressure reaching the skin surface on the PDMS flexible substrate.The pressure sensor detection value can better evaluate the true shock wave pressure on the skin surface.Finally,2 × 2 array flexible pressure sensor and multi-channel pressure acquisition system have achieved the collection of sensor voltage signals and obtained the pressure distribution on the sensor surface under the action of balloon explosion shock wave.Based on the DAQ122 data collector,the detection of the output signal of the array pressure sensor has been achieved,and the waveform pattern is consistent with the numerical simulation results.Based on the STM32 microcontroller,a multi-channel pressure acquisition system has been designed and manufactured,which can store the output signals of pressure sensors in real-time.