Search

In order to meet the needs of the intestinal robot to obtain power stably through wireless methods in different positions and postures, and to reduce the volume of the intestinal robot as much as possible, the transmitting coil is required to have the ability to generate spatial multi-dimensional magnetic fields. A hybrid transmitting coil structure is proposed, which combines Helmholtz coil pair and saddle-shaped coil pair. The structure is compact, and its symmetry can be used to generate a three-dimensional magnetic field without dead zone through rotation. The characteristics of the two types of coils and the combined characteristics are analyzed separately. The simulation and experimental results show that at the excitation of 2 A current, the minimum transmission efficiency of 3.44% and the received power of 1 204 mW can be obtained at the center of the coil. The minimum positional uniformity is 88.1%, and the three-dimensional power coverage can be achieved.

As an implantable medical device, the transcutaneous wireless energy transmission (TET) system of biaxial actuated artificial anal sphincter (BAAS) after implantation in vivo is affected by the hyperplasia of the parcel. The coupling performance is obviously lower than that of in vitro experiments, which reduces the practical value in medical treatment. Based on the experimental results of the TET system of BAAS, mainly aimed at the problem of transmission angle caused by the hyperplasia of the parcel, the existing TET system is analyzed and studied, and the relation curve between transmission angle and transmission efficiency are obtained. The experimental results show that when the transmission distance is 30 mm, the transmission efficiency reaches more than 60%. When the transmission distance is 30 mm and the transmission angle is 20°, the average transmission efficiency of the experiment can reach 66.65%. When the transmission angle is 30°, the average transmission efficiency of the experiment can reach 59.96%. The maximum of charging temperature of the transmitting coil is 23 ℃, which will not cause low temperature scald to the human body. It can meet the performance requirements of the BAAS system and achieve the purpose of long distance and high efficiency transmission.

In order to ensure the stable operation of the miniature gastrointestinal robot inside the human body, a new type of wireless power transmission (WPT) system is presented. To fulfill the requirements of the work energy consumption, posture stability, energy supply stability, and size limitation of the intestinal robot, the design refers to the calculation of electromagnetic field theory and the optimization results of the spindle-shaped three-dimensional receiving coil model which based on the principle of electromagnetic field resonance. Accordingly, the transmitting coil adopts four sets of solenoid coils to generate a uniform alternating magnetic field. With the receiving coil integrated inside, the optimized transmitting coil can generate a stable energy greater than 500 mW for a robot to work through mutual inductance. Relevant experimental verification indicates that performance of the wireless energy supply system satisfies the working requirements of the robot in the complex environment inside the intestine.

The wireless powered intestinal robot transmits the intestinal images taken by the image acquisition system to the external upper computer for diagnosis. However, the image transmission process will be interfered by the circuit structure and external environment, leading to noise in the collected images. Therefore, an image denoising algorithm based on non-subsampled contourlet transform (NSCT) is proposed to reduce the noise of the images collected by intestinal robots. First, histogram equalization pretreatment is adopted to improve the brightness and contrast of intestinal noise images. Next, NSCT transformation is performed on intestinal noise images and a residual network model is constructed to reduce the noise of frequency domain information after transformation. Finally, the denoised image is reconstructed by NSCT inverse transformation. The results show that the proposed algorithm can effectively reduce the influence of intestinal noise in complex environments, and better maintain the visual effect of the image. Compared with other intelligent algorithm models, both subjective and objective noise reduction effects are improved, with peak signal to noise ratio (PSNR) improved by 1.35 to 3.45 dB and structural similarity index measure (SSIM) improved by 0.0083 to 0.0252.

The biosafety and biocompatibility after implantation of the transcutaneous energy transfer system of artificial anal sphincter is verified by combining simulation and experiment in this paper. The biosafety study is based on the simulation of bioelectromagnetic radiation experiment and the thermal rise during the charging period while the biocompatibility study is based on the coloration experiment of the tissue around the energy supply system during the in vivo experiment. The results of biosafety indicate that the transcutaneous energy transfer system performs excellently in bioelectromagnetic safety in the experimental environment with a resonance frequency of 110 kHz and an output power of 10 W. In addition, the local specific absorption rate is far below the international human electromagnetic safety standard. After 30 minutes of fast charging, the system temperature increases by 2.81 ℃, which is lower than the temperature threshold of 4.8 ℃, demonstrating the outstanding biothermal safety of the system. The section staining experiment of the wireless energy supply system indicates that the poly-ether-ether-ketone (PEEK) shell can significantly reduce immune rejection and improve the biocompatibility of the system.

Based on the hardware of the new artificial anal sphincter system, this paper analyzes the power consumption of each module. After low-power consumption design and reasonable setting of the sampling period, the system power consumption is significantly reduced. At the same time, the area under the rectal pressure waveform is used as the standard for judging defecation willingness. Instead of the single-point pressure threshold method, it provides a basis for anal incontinence patients to go to the toilet, and thus improves the accuracy of the rectal perception function. Combining in vitro and in vivo experiments, the low-power consumption of the artificial anal sphincter designed in this paper can extend the working time of the system to 16 d after a single charge. It increases the working time by 230% with a rectal perception accuracy of 96%.

Piezoresistive pressure sensors have broad applications but often face accuracy challenges due to temperature-induced drift. Traditional compensation methods based on discrete data, such as polynomial interpolation, support vector machine (SVM), and artificial neural network (ANN), overlook the thermal hysteresis, resulting in lower accuracy. Considering the sequence-dependent nature of temperature drift, we propose the RF-IWOA-GRU temperature compensation model. Random forest (RF) is used to interpolate missing values in continuous data. A combination of gated recurrent unit (GRU) networks and an improved whale optimization algorithm (IWOA) is employed for temperature compensation. This model leverages the memory capability of GRU and the optimization efficiency of the IWOA to enhance the accuracy and stability of the pressure sensors. To validate the compensation method, experiments were designed under continuous variations in temperature and actual pressure. The experimental results show that the compensation capability of the proposed RF-IWOA-GRU model significantly outperforms that of traditional methods. After compensation, the standard deviation of pressure decreased from 10.18 kPa to 1.14 kPa, and the mean absolute error and root mean squared error were reduced by 75.10% and 76.15%, respectively. [ABSTRACT FROM AUTHOR]

Consider time-harmonic electromagnetic wave scattering by an infinitely long, cylindrical, orthotropic dielectric partially coated with a very thin layer of a highly conductive material, which can be modeled by a transmission problem with mixed boundary conditions. Having established the well-posedness of the direct and interior transmission problem by the variational method under certain conditions, we make use of the classical linear sampling method to reconstruct the shape of the obstacle. Then, based on a modification of the general data-to-pattern operator G, we propose a novel and simple method to justify the modified linear sampling method. [ABSTRACT FROM AUTHOR]

In this paper, we consider the inverse scattering problem of identifying a two-layered cavity by internal acoustic measurements under the condition that the interior interface has a mixed transmission boundary condition. We focus on the mathematical analysis of recovering the shape of the interior interface by using the linear sampling method, including reconstructing the surface conductivity by the same measurements. [ABSTRACT FROM AUTHOR]

Background: The artificial anal sphincter (AAS) system has gained significant attention as a solution for treating fecal incontinence (FI). It relies on transcutaneous energy transfer (TET) as its primary energy source. However, changes in posture or biological tissue can cause misalignment of the coil, resulting in unstable power reception. Inadequate power affects charging efficiency, while excessive power leads to excessive heating at the receiver side. Consequently, achieving safe and constant voltage charging for the AAS becomes a complex challenge. Methods: To maintain a consistent charging voltage and overcome the issue of variations in load and coil coupling strength, this article proposes a wireless charging control system that utilizes an LCC‐S‐type resonant network and phase shift to adjust the transmitting voltage based on feedback charging voltage in real time. In particular, the PI controller and neural network are introduced to change the phase‐shift angle swiftly. The dynamic performance is then evaluated under different misalignments and presented with comparative results. Results: The results indicate that the multilayer perceptron control system outperforms the PI. Under the complex misalignment disturbance, the average error of receiver side load voltage is only 0.007 V, with an average settling time of 960 ms. Additionally, the average temperature at the receiver side is 40.4°C. Conclusion: The experiments demonstrate that the proposed system effectively addresses the misalignment issue in TET during the charging, ensuring constant voltage charging at the receiver side and thermal safety. [ABSTRACT FROM AUTHOR]