Bioinspired flexible piezoresistive sensor for high-sensitivity detection of broad pressure range

The human skin has the ability to sense tactile touch and a great range of pressures.Therefore,in prosthetic or robotic systems,it is necessary to prepare pressure sensors with high sensitivity in a wide measurement range to provide human-like tactile sensation.Herein,we developed a flexible piezoresistive pressure sensor that is highly sensitive in a broad pressure range by using lotus leaf micropatterned polydimethylsiloxane and multilayer superposition.By superposing four layers of micropatterned constructive substrates,the multilayer piezoresistive pressure sensor achieves a broad pressure range of 312 kPa,a high sensitivity of 2.525 kPa^(−1),a low limit of detection(LOD)of<12 Pa,and a fast response time of 45 ms.Compared with the traditional flexible pressure sensor,the pressure range of this sensor can be increased by at least an order of magnitude.The flexible piezoresistive pressure sensor also shows high robustness:after testing for at least 1000 cycles,it shows no sign of fatigue.More importantly,these sensors can be potentially applied in various human motion detection scenarios,including tiny pulse monitoring,throat vibration detection,and large under-feet pressure sensing.The proposed fabrication strategy may guide the design of other kinds of multifunctional sensors to improve the detection performance.

Pressure ranges of velocity splitting of ablated particles produced by pulsed laser deposition in different inert gases

The transport of ablated particles produced by single pulsed-laser ablation is simulated via Monte Carlo method. The pressure ranges of velocity splitting of ablated particles in different inert gases are investigated. The result shows that the range of velocity splitting decreases with the atomic mass of the ambient gas increasing. The ambient gas whose atomic mass is more than that of Kr cannot induce the velocity splitting of ablated particles. The results are explained by the underdamping model and the inertia flow model.

Focused electron beam transport through a long narrow metal tube at elevated pressures in the forevacuum range

We present here our investigations of the features of focused electron beam transport in free space at elevated pressures of a few pascals.We have explored the effect of the beam accelerating voltage,operating gas pressure,and magnetic focusing upon the trajectory of beam electrons in the crossover region,in particular on the beam convergence and divergence angles.It is shown that for the forevacuum pressure range of 2-5 Pa explored,a distinctive feature of the propagation of a focused electron beam with a current of up to 20 mA at an accelerating voltage of 10-20 kV is the difference in the angles of convergence(before the focus)and divergence(after the focus).Whereas at a low pressure of 2 Pa the divergence angle is smaller than the convergence angle,as the pressure increases the divergence angle increases and for pressures greater than 5 Pa the divergence angle is greater than the convergence angle.The results obtained were used in experiments on electron beam transport through a long narrow metal tube with a diameter of 5.8-9.2 mm and length of 10-30 cm.We show that for a 30 cm long tube of 7.5 mm diameter,the focused beam transmission can exceed 70%.

Intrinsic Zero-Linear and Zero-Area Compressibilities over an Ultrawide Pressure Range within a Gear-Spring Structure

Materials with zero-linear compressibility(ZLC)and zero-area compressibility(ZAC)have great promise for specific applications retaining constancy in specific directions or planes under external impaction.To date,no more than 10 ZLC/ZAC materials have been reported,most of which have very limited working pressure ranges(<10 GPa).Herein,we report the observation of ZLC and ZAC in Li2Ti(IO3)6 with a gear-spring type structure over an ultrawide pressure range(0–40 GPa).

Seismic reliability analysis of shield tunnel faces under multiple failure modes by pseudo-dynamic method and response surface method

In order to investigate the stability problem of shield tunnel faces subjected to seismic loading,the pseudodynamic method(P-DM)was employed to analyze the seismic effect on the face.Two kinds of failure mechanisms of active collapse and passive extrusion were considered,and a seismic reliability model of shield tunnel faces under multifailure mode was established.The limit analysis method and the response surface method(RSM)were used together to solve the reliability of shield tunnel faces subjected to seismic action.Comparing with existing results,the results of this work are effective.The effects of seismic load and rock mass strength on the collapse pressure,extrusion pressure and reliability index were discussed,and reasonable ranges of support pressure of shield tunnel faces under seismic action were presented.This method can provide a new idea for solving the shield thrust parameter under the seismic loading.

A Research for Error Compensation Algorithm of Dual Range Pressure Sensor

Large range-high precision measurement has always been a challenge in the field of mechanical measurements. This paper built the input-output differential equation of Dual Range Pressure Sensor(DRPS) and gave an error compensation algorithm of DRPS after analyzing the mathematical model of DRPS. For a given situation, dynamic measurement errors of sensor parameters can be compensated by this method. Finally the accuracy and feasibility of the method were verified using Adams Software.

Fabrication of a Flexible Electric Skin Using a Bionic Cell and Study of Its Sensing Ability

Imitating the structure and function of the Pacinian corpuscle in the human body,a Bionic Cell(BC)with a liquid core was designed and made with polyvinylidene fluoride(PVDF),and an Electronic Skin(ES)sensor was successfully obtained by embedding the BCs into silicone rubber.The passive sensing ability of the ES for surface vibration pressure was measured.The results showed that the ES could detect waveform,frequency,amplitude and other parameters of the surface,and it exhibited not only a high sensitivity of 0.46563 fc/Pa,but also a large pressure measurement range of 0.6 Pa–6014 Pa.A falling real object impact experiment was carried out,and the results indicated that the ES output charge was linearly related to the falling height of the object and logarithmically related to the mass of the object.Then,a crawling insect experiment and human pulse experiment were performed to study the perception ability of the ES to irregular pressure.Due to its special structure,simple fabrication process,and high sensitivity wide measurement range,the ES fabricated in this paper is expected to be used as robot skin with tactile perception ability in the near future.