Sensors and Actuators A-physical最新文献

In this manuscript, a microwave sensing system for extracting complex permittivity of binary aqueous solutions based on a modified microstrip line with interdigital structure (IDS) etched is proposed. The passive resonance unit and active circuits constitute the microwave sensing system. The passive resonance unit is evolved from conventional microstrip line with the characteristic impedance of $50\Omega$, then the IDS is etched on the top surface of passive resonance unit to enhance the confinement of electrical field. The modified passive sensor can produce two resonant modes, i.e., odd-mode 1 and odd-mode 2, the electrical fields of these two modes are both concentrating at IDS, and odd-mode 1 with higher density of electrical field is adopted to retrieve complex permittivity of liquid samples. Except for the passive sensor, the sensing system consists of power divider, low noise amplifier (LNA), isolator, orthogonal hybrid coupler, phase shifter, mixer, and low-pass filter (LPF). The proposed microwave sensing system has two output DC voltages, i.e., channel-I and channel-Q. The mathematical relationship between complex permittivity and resonant frequency shift can be transformed into the relation between complex permittivity and two DC voltages by the proposed microwave sensing system, which is beneficial to discard the use of VNA. The two output voltages of microwave sensing system will be changed according to the injections of liquid samples with different complex permittivity, then the mathematical models can be established by summarizing the rule between complex permittivity and DC voltages. Finally, the established mathematical models can be adopted to predict the binary aqueous solutions with unknown complex permittivity. In measurement, the proposed microwave sensing system has the average sensitivities of about 2.478 mV/${\epsilon }_r^{\prime }$ and 1.418 mV/${\epsilon }_r^{\prime }$ for channel-I and channel-Q, respectively, which are several times higher than other reported ones. Low-cost, high sensitivity, convenient measurement, and easy fabrication are the merits for the proposed sensing system, and it is a good template in the region of detecting liquid samples.

Currently, traditional tactile sensors based on the principles of capacitance or piezoelectricity have complex structures and difficulty in obtaining tactile information. A vision-based tactile sensor is introduced which can realize visual measurement of three-dimensional displacement in this paper. The vision-based tactile sensor is mainly composed of an elastomer embedded with marker point array, a transparent acrylic plate, 8 LED lights and a micro monocular camera. The elastomer deforms when the tactile sensor contacts an object, and the micro monocular camera is used to capture the elastomer deformation and transmit it to the computer in the form of image, and then the three-dimensional displacement information is obtained by processing the image. In order to more accurately recover the missing dimensional information in the three-dimensional displacement detection of monocular camera, an improved DFD (Depth from Defocus) method based on finite element theory is proposed in this paper. It is verified by experiments that the improved DFD method proposed in this paper can measure the three-dimensional displacement information more accurately compared with the DFD method. In addition, an experiment is conducted to prove the robustness of the improved DFD method on the robotic gripper. The experimental results demonstrate that the three-dimensional displacement measurement method proposed in this paper can provide technical support for the design and development of vision-based tactile sensors.

Wearable pressure sensors with exceptional performance are playing a crucial role in various fields such as electronic skin, human motion monitoring, medical diagnosis, and human-computer interaction. However, achieving both high sensitivity and a wide sensing range with simple fabrication and low cost has proven to be a significant challenge for sensors. In this study, a simple capacitive pressure sensor is proposed that multi-walled carbon nanotubes (MWCNTs) are introduced into MXene (Ti₃C₂T_X) as a ‘bridge’. Then the electrode which has excellent conductivity is obtained by filtration of MXene solution and MXene/MWCNTs solution at intervals. Additionally, green and degradable cellulose paper is used as the dielectric layer. The fabricated pressure sensor exhibits a high sensitivity of 4.7 kPa⁻¹ for low pressure from 0 to 1 kPa, a wide detection range of 0–700 kPa, ultra-fast response and recovery times of 46 ms and 62 ms, respectively, and an extremely low detection limit of 0.32 Pa. The sensor remains stable even after 4500 cycles and can accurately monitor the movement of the human joints. Furthermore, it can track human physiological signals, which is beneficial for medical diagnosis and disease prevention, and has significant potential for application in the wearable technology field.

Acoustically actuated bubbles provide a versatile and non-invasive approach for manipulating microorganisms in fluid. However, the susceptibility of the bubble volume to environment and the complex intersecting vortices of the oscillation of hemispherical bubbles reduce the stability of micromanipulation of ellipsoid-like organisms. This study involves an on-chip rotational manipulation device for rotating ellipsoid-like organisms, which utilizes parallel microstreaming vortices that are generated with acoustically actuated semi-capsule-shaped bubbles. In addition, a relatively stable volume of the semi-capsule-shaped bubble with tolerances about 5 % is realized by adjusting the gas diffusion between the bubble and the gas channel. Characterized experiments using polystyrene particles of 10 μm demonstrate that two pairs of significant out-of-plane parallel microstreaming vortices can be generated near the short or long side of a semi-capsule-shaped bubble at acoustic driving frequencies of 11.23 kHz and 13.97 kHz, respectively. The vortices effectively induce rotation both for the spherical particles and the ellipsoid-like paramecia in fluid. Compared to oscillating hemispherical bubbles, acoustically actuated semi-capsule-shaped bubbles offer a more stable attitude of the rotation axis and even rotation velocity for paramecia. The acoustically actuated semi-capsule-shaped bubbles offer a label-free method for rotational manipulation of ellipsoid-like organisms, characterized by good stability, adaptability, and biocompatibility.

Fringe projection profilometry with temporal phase unwrapping (FPP-TPU) has been gotten more and more attention in reconstructing the object with complex surfaces. However, a general contradiction in the existing FPP-TPUs is that more auxiliary coded patterns may limit sampling rate in dynamic three-dimensional (3D) measurement. In this paper, inheriting the single-frame auxiliary pattern of the phase-shifting temporal phase unwrapping (PS-TPU), an improved phase shift coding temporal phase unwrapping with higher robustness is proposed. And new projection stratagem with phase shift coding division multiplexing (PSC-DM) is also proposed to enhance the reconstructing rate in dynamic 3D scene. Firstly, six codewords instead of the traditional eight codewords are embedded into the single-frame auxiliary coding pattern, which guarantees the decoding robustness and provides a faster decoding process with single-step direction unifying. Then, the new projection sequence stratagem is designed with every two sets of 3-step phase-shifting patterns projection followed by the single-frame phase-shifting coding pattern projection. During phase unwrapping, every adjacent three frames of phase-shifting pattern sequentially resolving a wrapped phase and a highly robust 3D reconstruction can be achieved by using the closest phase-shifting coding pattern so as to achieve phase-shifting coding division multiplexing. It can obtain higher reconstructing rate. In addition, a phase shift segmentation is used to correct mismatched errors of fringe order. The experimental results demonstrate that the proposed method can increase the reconstructing rate from the rate of 30 fps in traditional PS-TPU method to 68.57 fps at the digital light projector (DLP) projection rate of 120 fps, which shows its potential prospective in dynamic 3D shape reconstruction.

Wireless power transfer is a key feature in the field of biomedical engineering. It allows a reduction of the energy storage devices in medical implants. An efficient way to safely transfer energy to medical implants is to convey ultrasounds through the body to a Capacitive Micromachined Ultrasonic Transducer (CMUT). For an application of ultrasonic energy transfer through skin, the present work compares the efficiency of two different electronic architectures to receive energy from an array of CMUT. The well known Synchronous Switch Harvesting on Inductor (SSHI) is compared in simulation to a simple impedance matching. Indeed, for an ultrasonic energy transfer, the high excitation frequency (1–8 MHz) allows the use of an inductor matching the CMUT’s clamped capacitor. The simplicity of an impedance matching circuit, its low volume and its efficiency makes it the best choice for an efficient energy transfer process to the targeted load. The CMUT model used in the simulations is a mason’s model which component values are extracted from the impedance measurement of a real device. In the end, the impedance matching is experimentally tested on this same device and compared to the simulation. A maximum 4,5 mW power is transferred to an optimal load for an input ultrasound pressure of 90 kPa.

The timely detection and monitoring of toxic gases are crucial for preserving the ecological environment and preventing their adverse effects on human health. In this study, we investigate the adsorption characteristics and sensitivity performance of Pd- and Pt-decorated InSe monolayers, referred to as Pd-InSe and Pt-InSe, towards five toxic gases (CO, NO, NH₃, H₂S, and SO₂) using first-principle calculations. The results show that the doping of Pd and Pt atoms significantly improves the conductivity, adsorption capabilities, and sensing properties of InSe monolayer to these toxic gases. Both Pd-InSe and Pt-InSe monolayers exhibit chemical adsorption of CO, NO, NH₃, and H₂S, with adsorption energies ranging from –0.56 eV to –1.04 eV, leading to noticeable changes in the bandgap (8.84 % ∼ 31.03 %). Furthermore, the CO/Pd-InSe and H₂S/Pt-InSe systems demonstrate excellent sensitivity, with high sensing response values of 1.54×10⁴ and 66.20, respectively, and their sensitivity remains unaffected under humid environments. Importantly, Pt-InSe exhibits a fast recovery time of 0.05 s at 298 K, making it highly promising for the recyclable detection of H₂S at room temperature. In contrast, Pd-InSe can be utilized as a reusable gas sensor for CO at 448 K with a good recovery time of 0.5 s. This work can provides theoretical guidance for the design and fabrication of InSe-based gas sensors for the detection of toxic gases.

Wireless power transfer is an essential feature of biomedical engineering. It reduces the need for energy storage devices in medical implants. To recharge a body implanted battery, a convenient way is to transmit ultrasounds through the skin to a connected ultrasonic transducer. Lead-less, System-on-Chip compatible (SoC) and wideband, Capacitive Micromachined Ultrasonic Transducers (CMUT) are competitive with piezoelectric based technologies. However, their need for a high bias voltage is an obstacle to their use in implanted medical devices (IMDs). The voltage source required must meet precise specifications, such as reliability and volume, which the research community intends to respect. To meet this challenge, this work proposes an electronic circuit that allows a CMUT device to self-bias from a very low initial energy input. After presenting the electronic architecture and its main features, simulation and experimental results validate the solution’s working principle and operating points. With an electronic circuit made up of discrete components, a bias voltage of 60 V is built up from an implanted battery voltage of 2.2 V and an incident pressure of 120 kPa in water.

Nonlinear magneto-optical rotation (NMOR) atomic magnetometers demonstrate exceptional sensitivity in the geomagnetic environment, making them highly attractive for applications in resource exploration, biological research, and fundamental physics studies. Nevertheless, the presence of the “dead zone” hampers the magnetometer’s capacity to detect magnetic fields with sensitivity. In this paper, we present a method for effectively mitigating the “dead zone” by simultaneous detection of alignment and orientation polarization. Based on the standard formalism of density matrix and Liouville Equation, theoretical models of alignment and orientation resonance signals as a function of the magnetic field are developed. Additionally, due to the large light intensity used in the actual system, the alignment to orientation conversion (AOC) effect has been taken into account to reveal a more complete model. The influence of light intensity on the alignment and orientation signals are investigated. It is found that there is an optimal theoretical light intensity, which makes the suppression effect of the “dead zone” best. The theoretical model aligns well with the experimental phenomenon and successfully minimizes the extent of the “dead zone”.

A highly conductive yarn was developed by electroless deposition of copper metal particles on the polyamide 6 yarn. The successful incorporation of Cu particles into the substrate was revealed by surface and elemental characterizations. The Cu/PA 6 yarn exhibited superior electrical conductivity (2.3 Ω/cm) with improved mechanical properties. The excellent electromechanical properties demonstrated by the Cu/PA 6 composite revealed its sensing capacity for a wide range of strains. Therefore, the composite yarn was affixed to the different regions of the human body and was capable of successfully monitoring various human motions, including finger bending, wrist bending, knee bending, drinking, and writing. In addition, rapid heat generation with high and uniform surface temperature (66.3 °C at 4.0 V in 45 s) validated the potential of the Cu/PA 6 yarn for wearable thermal heating devices. Moreover, rapid heating at a lower voltage, when attached to a wristband, revealed the capability of the composite yarn for localized heating or region-specific temperature regulation for personalized healthcare or comfort. This study informs a facile and effective strategy for developing robust yarn-shaped e-textiles for advanced wearable sensing and thermal heating.