Robust voltage-controlled transcutaneous energy transfer system for artificial anal sphincter.

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.

Simulation of artificial anal sphincter motion and interaction with intestinal environment using SOFA.

BACKGROUND: Artificial anal sphincter is an implantable medical device for treating fecal incontinence. Reasonable simulation facilitates the advancement of research and reduces experiments on biological tissue. However, the device's clamping motion and sensor interaction with the intestine in the simulation still require further exploration. This article presents a simulation of the artificial anal sphincter's clamping and sensing and its interaction with the intestinal environment using the Simulation Open Framework Architecture (SOFA). METHODS: Firstly, the proposed simulation algorithm and its principles in SOFA are analyzed. Secondly, the clamping motion and sensor system of the artificial anal sphincter are simulated. Thirdly, a finite element model of intestine is established based on the properties of intestinal soft tissue. Finally, the in vitro experiments are performed. RESULTS: The simulation results indicate that the sensor system of the artificial anal sphincter has good sensing performance during the clamping motion and fecal accumulation process. Experiments have shown that optimal sensory capabilities can be achieved as the posture of the artificial anal sphincter with a roll angle between 20° and 40°. The comparison demonstrates a mean absolute error of 10%-20% between simulation and in vitro experimental results for sensor forces, which verifies the effectiveness of the simulation. CONCLUSION: The proposed novel simulation achieves a more comprehensive interaction between the artificial anal sphincter motion and intestinal environment. This study may provide more effective simulation data for guidance in improving the performance of sensor perception of artificial anal sphincter for further research.

Preliminary study of a novel artificial anal sphincter with perception reconstruction.

BACKGROUND: Artificial anal sphincter (AAS), as an advanced device, has been widely investigated by researchers around world. But the reliability of the structure is still unsatisfactory according to clinical results. What's more, the previous AAS systems are lack the ability of rectal perception as native anal sphincter, which fails to guarantee the safety of the blood supply. In addition, without it, the patient cannot determine when to defecate. METHODS: In order to improve the reliability and safety of current AAS systems, a novel structure AAS system with rectal perception function, based on pressure sensor module, is proposed in this article. The novel AAS system has a closed three-arm clamping mechanism, with transmission structure of cam-follower system. Then, the design, strength check, optimization and force analysis of the proposed mechanism are investigated. After that, to remodel rectal perception function, the novel sensor module system based on strain gauge is established. Finally, in vitro experiments are conducted. RESULTS: In vitro test, the sensor system could monitor the rectal pressure accurately. And when H = 24.6 cm (feeling the urge to have a bowel movement), the clamping pressure is 7.39 kPa. which is also less than the safe pressure 9.33 kPa. CONCLUSIONS: Good performance of the reliability and safety of both novel rectal perception function and new clamping mechanism have been showed.

Design and evaluation of perception reconstruction with sensor system for artificial anal sphincter based on vector similarity.

BACKGROUND: Artificial organs are playing an increasingly important role in medical field. Artificial anal sphincter, as an example, is a widely used medical device for fecal incontinence. Though it could help patients maintain continence, the issue of perception reconstruction is still unsolved, which means that patients cannot control defecation as desired. METHODS: In this paper, a novel sensor system based on vector similarity has been analyzed and evaluated. The sensor system is a self-packaged strain gauge sensor with a small size 14.5 mm × 6 mm, especially for medical device implanted in body to reconstruct perception function. In order to overcome the disadvantages of single threshold judgment, a more accurate and reliable judgment standard for content pressure detection in rectum is developed by using vector similarity method. Therefore, in the novel sensor system, standard multi-parameters are comprehensive considered. Furthermore, weight-optimization of sensors are investigated since each sensor has played a different role in detection. Finally, sensor calibration, in vitro and in vivo experiments are established. RESULTS: In sensor calibration, the result R2 > 0.99 presents the strain gauge pressure sensor has a good linearity. After that, a series of in vitro experiments have been conducted. The optimized sensor system shows a high accuracy rate in perception reconstruction, which is 87.5% on early warning and 95% on the alarm. In the following in vivo experiments. The results indicate that the average accuracy of the proposed perception reconstruction module has increased by 17.7%, compared with that without optimized sensor system. CONCLUSIONS: All of these have proven that the novel perception reconstruction module with sensor system based on vector similarity is more acceptable and reliable.

A Novel Sensor System for In Vivo Perception Reconstruction Based on Long Short-Term Memory Networks.

Monitoring bodily pressure could provide valuable medical information for both doctors and patients. Long-term implantation of in vivo sensors is highly desirable in situations where perception reconstruction is needed. In particular, for fecal incontinence, artificial anal sphincters without perceptions could not remind patients when to defecate and even cause ischemic tissue necrosis due to uncontrolled clamping pressure. To address these issues, a novel self-packaging strain gauge sensor system is designed for in vivo perception reconstruction. In addition, long short-term memory (LSTM) networks, which show excellent performance in processing time series-related features and fitting properties, are used in this article to improve the prediction accuracy of the perception model. The proposed system has been tested and compared with the traditional linear regression (LR) approach using data from in vitro experiments. The results show that the Root-Mean-Square Error (RMSE) is reduced by more than 69%, which demonstrates that the prediction accuracy of the proposed LSTM model is higher than that of the LR model to reach a more accurate prediction of the amount of intestinal content. Furthermore, outcomes of in vivo experiments show that the robustness of the novel sensor system based on long short-term memory networks is verified through experiments with limited data.

An artificial anal sphincter based on a novel clamping mechanism: Design, analysis, and testing.

An artificial anal sphincter is a device to help patients with fecal incontinence rebuild the ability to control the excrement through the anus. In this article, an artificial anal sphincter based on a novel clamping mechanism (AASNCM) is proposed to improve the safety and reliability. The AASNCM, which is powered by a transcutaneous energy transfer system, consists of a novel clamping mechanism, a receiving coil and a control unit. According to design requirements, the novel clamping mechanism model was established. After that, its kinematics and dynamics were analyzed. The results of force tests on the prototype AASNCM show that the maximum values of clamping force and expanding force are 15.859 and 31.029 N, respectively. Comparing the experimental results with theoretical analysis, a good match can be concluded. Finally, in vitro experiments were conducted, and have verified the safety and reliability of the proposed AASNCM.

Modelling on mutual inductance of wireless power transfer for capsule endoscopy.

Wireless capsule endoscopy (WCE) is noninvasive, painless, and riskless on detection for gastrointestinal disease. It attracts increasing attention. Wireless power transfer (WPT) technology is utilized to supply power for WCE. Receiving coil (RC) of WPT is capsulated into WCE. Its position and direction change all through gastrointestinal tract. Transmitting coil (TC) is worn by the patient. So the mutual inductance varies all the time. It should be studied to ensure sufficient receiving power. However, existing analytical methods do not reach satisfactory accuracy. They can only solve simple cases with positional misalignment. Numerical simulation models are time-consuming. Furthermore, an entirely new simulation must be repeated when any change in alignment occurs. Thus, based on geometry and misalignment of RC and TC, a model for mutual inductance is proposed. Compared with analytical methods, it is applicable to not only circular and rectangular RC, but also the elliptic, with directional misalignment. It costs below 0.1% of computational time of the simulation for the same accuracy. Moreover, any change in misalignment is easily handled by a simple change of parameter in the model. It reaches a tradeoff between computational accuracy and time. Receiving power is evaluated rapidly and accurately with proposed model.

Design and testing of a novel gastrointestinal microrobot.

In order to improve the reliability, safety and whole digestive applicability of the gastrointestinal microrobot (GMR), a novel inchworm-like GMR is proposed in this paper. The expanding mechanism of the robot adopts an overlapping expanding arm structure. This structure increases the variable diameter ratio (ratio of fully expanded diameter to fully folded diameter) of the robot to 3.3, making the robot more applicable to the intestines in various parts of the human body. The mechanical model of the expanding arm is established, and the expanding force at different expanding radii is obtained. And then the expanding force is tested by a force test platform. The force test results: the maximum expanding force is 6.5 N, and the minimum expanding force is 1.3 N. The trend of the experimental and theoretical values is the same, and the experimental value is less than the theoretical value. A position limiting device based on Hall sensor is designed, which detects whether the mechanism reaches the limit position by non-contact method. This device alleviates the problem of sharp voltage drop caused by motor stall and improves the stability of the control circuit. The results of the Hall-type position limiting device (HPLD) testing show that the working currents of the expanding mechanism and the telescoping mechanism with HPLD are respectively 0.066A and 0.110A, and the robot control circuit works stably. Finally, the robot is tested in the intestine of the living pig, and the safety and reliability of the robot are verified. However, due to the decrease of the efficiency of wireless power transmission in vivo experiments and the change of the position of the receiving coil relative to the transmitting coil, sometimes the power supply is insufficient.

The evaluation of GI-pill gastrointestinal electronic capsule for colonic transit test in patients with slow transit constipation.

OBJECTIVE: The evaluation of GI-pill gastrointestinal electronic capsule for colonic transit test in patients with slow transit constipation (STC) was studied. MATERIALS AND METHODS: STC patients (n = 162) were randomly divided into experimental group (n = 84, orally taken GI-pill gastrointestinal electronic capsule and X-ray granule capsule) and control group (n = 78, orally taken X-ray granule capsule). Comparison of the time in colonic transit test between the two groups was conducted. The data of GI-pill gastrointestinal electronic capsule in vivo time, time of capsule passing through the colon, the number of high amplitude propagating contractions (HAPCs), and physiological response ratio were analyzed. RESULTS: There were no significant differences in the whole colonic transit test time, right colonic transit time, left colonic transit time, and rectosigmoid colonic transit time between experimental group and control group (p > 0.05). All patients had no abdominal pain, nausea, vomiting, black stool, difficulty in electronic capsule excretion, or any other discomfort during the test. CONCLUSION: GI-pill gastrointestinal electronic capsule can continuously evaluate the dynamic characteristics of digestive tract in STC patients and is consistent with X-ray granule capsule, which is meaningful to clinical application.

Design and evaluation of puborectalis-like artificial anal sphincter that replicates rectal perception.

While fecal incontinence (FI) is not fatal, it can dramatically decrease the patient's quality of life. An artificial anal sphincter (AAS) is an implantable device that treats FI by replacing a diseased or damaged anal sphincter, thus allowing the patient's continence to be maintained. Here, we report a novel implantable puborectalis-like artificial anal sphincter (PAAS) that replicates rectal perception and has a low risk of ischemia necrosis. Using the pressure sensors embedded in the PAAS, the relationship between the mass of feces and the pressure was determined, and a feces mass estimation model was developed based on in vitro studies. Rectal perception is provided through the real-time monitoring of rectal feces, and the feeling of defecation is quantified based on a comparison between the feces mass and a preset threshold mass. In vivo studies were performed for validation, and the accuracy of the model was determined to be as high as 90%. The performance of the PAAS in the real-time monitoring of rectal feces and its in vivo biocompatibility were also evaluated. The device should further the functionality of existing AAS systems while improving their biosafety and thus expand the applicability of implantable AAS systems in the treatment of FI.

[Design of Wearable Wireless Health Monitoring System and Status Recognition Algorithm].

A wearable wireless health monitoring system for drug addicts in compulsory rehabilitation centers was proposed. The system can continuously monitor multiple physiological parameters of drug addicts in real time, and issue early warning information when abnormal physiological parameters occur, so as to play the role of timely medical practice. In addition, this study proposes a convolutional neural network (CNN)model, which can evaluate the health status of drug addicts based on multiple physiological parameters. Experiments show that the model can be applied to the task of body state recognition in the open physiological parameter data set, and the recognition accuracy can reach up to 100% in a single physiological parameter data set; when the whole physiological data set is used, the recognition accuracy can reach 99.1%. The recognition accuracy exceeds the performance of the traditional pattern recognition method on this task, which verifies the superiority of the model.

A novel power supply system for puborectalis-like artificial anal sphincter.

Puborectalis-like artificial anal sphincter (PAAS) is an innovative new type of artificial anal sphincter (AAS). It overcomes many drawbacks and inadequacies of various previous AASs, and it has successfully been implanted in vivo for almost 3 weeks. During in vivo testing, PAAS shows its ability to retain continence with low risk of ischemia necrosis, and somehow truly helps to remodel rectal perception. However, there are still many defects that influence the long-term implantation of PAAS, especially in the power supply system (PSS). This article presents a new designed PSS which includes a new transcutaneous energy transfer (TET) system, a heat reduction system, and a safety usage system. The new PSS reduces the total size of PAAS by at least 30%. Newly designed TET system can satisfy the Qi standard, and render a power of 3W to fulfill the requirement of fast charging and normal use of PAAS at the distance of 15.5 mm when frequency of TET system is 110 kHz, which previous TET systems can hardly achieve. Heat reduction system helps to reduce the heat generated during TET charging. It can reduce heat by 40% during the same period of time of TET charging. Safety usage system helps the user control PAAS more properly which can reduce the rate of failure of PAAS system.

Preliminary Study of a Novel Puborectalis-Like Artificial Anal Sphincter.

Artificial anal sphincter (AAS) is an in situ implanted device that acts as a treatment for fecal incontinence regardless of etiology by augmenting the incompetent sphincteric structures. However, AAS is impeded from becoming a valid therapy by its high rate of ischemic complication and malfunction. This article presents an original puborectalis-like artificial anal sphincter (PAAS) that features a low risk of ischemia necrosis and rectal perception remodeling. The device retains continence by reproducing the action, including the pulling and angulating the rectum, of the puborectalis muscle, which forms the anorectal angle and reduces the required clamping pressure. Three rectal pressure sensors were embedded to maintain the pressure exerted on the rectal wall in a safe range and to monitor the distention of the rectum. A series of in vitro studies were conducted with a porcine rectum, and this PAAS prototype manifested the ability of maintaining continence with a clamping pressure considerably lower than that required by other AAS devices. The pressure sensors exhibit good linearity, and the function of rectal perception remodeling has also revealed high reliability with a success rate of 93.3%.

[Improvement of Digital Capsule Endoscopy System and Image Interpolation].

Traditional capsule image collects and transmits analog image, with weak anti-interference ability, low frame rate, low resolution. This paper presents a new digital image capsule, which collects and transmits digital image, with frame rate up to 30 frames/sec and pixels resolution of 400 x 400. The image is compressed in the capsule, and is transmitted to the outside of the capsule for decompression and interpolation. A new type of interpolation algorithm is proposed, which is based on the relationship between the image planes, to obtain higher quality colour images. capsule endoscopy, digital image, SCCB protocol, image interpolation

Optimal Design of Litz Wire Coils With Sandwich Structure Wirelessly Powering an Artificial Anal Sphincter System.

Transcutaneous energy transfer system (TETS) is widely used to energize implantable biomedical devices. As a key part of the TETS, a pair of applicable coils with low losses, high unloaded Q factor, and strong coupling is required to realize an efficient TETS. This article presents an optimal design methodology of planar litz wire coils sandwiched between two ferrite substrates wirelessly powering a novel mechanical artificial anal sphincter system for treating severe fecal incontinence, with focus on the main parameters of the coils such as the wire diameter, number of turns, geometry, and the properties of the ferrite substrate. The theoretical basis of optimal power transfer efficiency in an inductive link was analyzed. A set of analytical expressions are outlined to calculate the winding resistance of a litz wire coil on ferrite substrate, taking into account eddy-current losses, including conduction losses and induction losses. Expressions that describe the geometrical dimension dependence of self- and mutual inductance are derived. The influence of ferrite substrate relative permeability and dimensions is also considered. We have used this foundation to devise an applicable coil design method that starts with a set of realistic constraints and ends with the optimal coil pair geometries. All theoretical predictions are verified with measurements using different types of fabricated coils. The results indicate that the analysis is useful for optimizing the geometry design of windings and the ferrite substrate in a sandwich structure as part of which, in addition to providing design insight, allows speeding up the system efficiency-optimizing design process.

Low-power wireless electronic capsule for long-term gastrointestinal monitoring.

Combining ASIC and multiple microsensors low-power wireless electronic capsule was developed for the long-term monitoring of the entire human gastro-intestinal (GI) tract. To meet the system requirements, several low-power designs were used in the wireless electronic capsule. The capsule measured 11 × 22 mm including batteries (45mAh). The capsule system's lifetime was 233 h, and it could meet the requirements of almost all clinical applications. A wireless electronic capsule, portable data recorder, and workstation comprised the human GI physiological parameters monitoring system. In this paper, this system was used in a clinical trial to compare colon peristaltic pressure between patients with constipation and healthy people.

[Recent Research Progress and Development Direction of Autofluorescence Diagnosis Technology].

Autofluorescence has great advantage on detecting premalignant lesions and early cancers which are not detectable by conventional white light endoscopy (WLE). In this review, the recent advances in autofluorescence for diagnosis of precancerous lesions and early cancers are presented. Varieties of endogenous fluorophores in biological tissues, the potential mechanisms of the autofluorescence differences between normal and abnormal tissues, the selection of light source and optimal excitation wavelengths, and effective algorithms for processing autofluorescence data are highlighted. Finally, the shortages and improvement directions of autofluorescence technique for the diagnosis of precancerous lesions and early cancers are briefly discussed.

[Latest development of intestinal capsule endoscopy robot].

With the development of capsule endoscopy, developing active capsule endoscopy robot becomes a growing trend. Although stomach diagnosis with robot has been put into clinical test, the realization of the complete intestinal capsule endoscopy is still a difficulty. This paper reports the status quo of the research process for intestinal capsule endoscopy robot, and analyzes their advantages, defects and prospects for development, which provides reference for the research of intestinal capsule endoscopy robot.

[A method for bleeding detection in endoscopy images using SVM].

Because the huge number of images of the digestive tract by Wireless Capsule Endoscopy (WCE) are left to the medical personnels detected by their eyes, huge burden leaves to doctors. This article provides a classification of method based on SVM (Support Vector Machine) for the capsule endoscopy bleeding intelligent recognition. We created a new kind of feature parameter, and the experiment result can reach 83% specificity and 94% sensitivity.

Characterizing the coefficient of friction between a capsule robot and the colon.

OBJECTIVE: A capsule robot (CR) with an onboard active locomotion mechanism, has been developed as a promising alternative to colonoscopy due to its minimally-invasive advantage. Predicting the traction force and locomotion resistance of the CR, which are both the friction force, is significantly important for the CR development and control. However, a comprehensive study concerning the coefficient of friction (COF) in the colon, which is necessary for prediction, is not available in literature. This paper is dedicated to determining a quantitative COF equation in terms of the contact pressure, hoop strain, and sliding velocity. METHODS: The COFs of three commonly-used materials of the CR (i.e., PDMS, white and transparent ABS plastic), are measured under 144 different friction cases (6 contact pressures×4 hoop strains×6 sliding velocities). By analyzing the measurements, the influence law of the three factors on the COFs of the three materials is revealed, and based on which, a general COF equation involving eight fitted constants is determined. RESULTS: The determination coefficients of the COF equation for the three materials are up to 0.9822, 0.9286, and 0.9696, respectively. The COF equation is used to predict the traction force and locomotion resistance of a crawler CR, and the predicting results fit well with the measured ones. CONCLUSION: The COF equation can provide a correct COF for friction force prediction. SIGNIFICANCE: It is promising to enable a better force and locomotion control for the CR in the colon.