Digital design of internal device of electro-magnetism excitation positioning for electronic capsule / 国际生物医学工程杂志

Objective To develop a digital signal processing method for magnetic positioning of electronic capsules according to the theory of multiple alternating magnetic field source electromagnetic positioning, so as to reduce the volume and power consumption of electronic capsules. Method Based on STM32 MCU, software algorithms such as fast digital filtering, peak detection and frequency detection were designed to replace the corresponding analog hardware circuits such as analog filtering, peak detection and comparison circuits. Results The experimental results showed that the average relative error of the peak detection and frequency detection of the digital signal processing system were 1.51％ and 0.28％ , respectively. The linear relationships of theoretical amplification factor and actual amplification factor of the programmable amplifier were basically consistent, and the average ratio difference was 4.51 dB. Conclusions The proposed digital signal processing system can replace some analog hardware circuits, providing a basis for reducing the size and power consumption of electronic capsules.

Intelligent regulation scheme of the gastrointestinal delivery capsule's driving force / 国际生物医学工程杂志

Objective To intelligently adjust the driving force of a remote-controlled drug delivery capsule based on the postural information in intestines,so as to achieve the control of speed and dosage of drug delivery and reduce the energy consuming.Methods A six-axis sensor MPU6050 was used,and its Z axis was coincident with the central axis of the drug delivery capsule so as to made the medicine discharge port pointing to the Z direction.The angular velocities and accelerations of X,Y,Z axes were monitored,transformed to quaternion with built-in digital motion processor,and then converted to Euler angle form.The intelligence adjustment of driving force could be achieved by accessing the real-time attitude angle of the capsule.Results The results of experiments showed that the error between the actual and the attitude angle measured by the sensor was less 1°.Conclusions The intelligent adjustment scheme of driving force of a gastrointestinal remote-controlled drug delivery capsule was designed.The real-time attitude angles of the capsule could be obtained with high spped and precision.This study can provide the theoretical and experimental basis for the intelligent adjustment of the driving force.

Design of Adjustable Magnetic Field Generating Device in the Capsule Endoscope Tracking System / 生物医学工程学杂志

The capsule endoscope swallowed from the mouth into the digestive system can capture the images of important gastrointestinal tract regions. It can compensate for the blind spot of traditional endoscopic techniques. It enables inspection of the digestive system without discomfort or need for sedation. However, currently available clinical capsule endoscope has some limitations such as the diagnostic information being not able to correspond to the orientation in the body, since the doctor is unable to control the capsule motion and orientation. To solve the problem, it is significant to track the position and orientation of the capsule in the human body. This study presents an AC excitation wireless tracking method in the capsule endoscope, and the sensor embedded in the capsule can measure the magnetic field generated by excitation coil. And then the position and orientation of the capsule can be obtained by solving a magnetic field inverse problem. Since the magnetic field decays with distance dramatically, the dynamic range of the received signal spans three orders of magnitude, we designed an adjustable alternating magnetic field generating device. The device can adjust the strength of the alternating magnetic field automatically through the feedback signal from the sensor. The prototype experiment showed that the adjustable magnetic field generating device was feasible. It could realize the automatic adjustment of the magnetic field strength successfully, and improve the tracking accuracy.

An implantable micro-device using wireless power transmission for measuring aortic aneurysm sac pressure / 生物医学工程学杂志

In order to detect endoleaks after endovascular aneurysm repair (EVAR), we developed an implantable micro-device based on wireless power transmission to measure aortic aneurysm sac pressure. The implantable micro-device is composed of a miniature wireless pressure sensor, an energy transmitting coil, a data recorder and a data processing platform. Power transmission without interconnecting wires is performed by a transmitting coil and a receiving coil. The coupling efficiency of wireless power transmission depends on the coupling coefficient between the transmitting coil and the receiving coil. With theoretical analysis and experimental study, we optimized the geometry of the receiving coil to increase the coupling coefficient. In order to keep efficiency balance and satisfy the maximizing conditions, we designed a closed loop power transmission circuit, including a receiving voltage feedback module based on wireless communication. The closed loop improved the stability and reliability of transmission energy. The prototype of the micro-device has been developed and the experiment has been performed. The experiments showed that the micro-device was feasible and valid. For normal operation, the distance between the transmitting coil and the receiving coil is smaller than 8cm. Besides, the distance between the micro-device and the data recorder is within 50cm.

Researches on Gastric Interdigestive Pressure Activity: Methods, Analysis and Interpretation.

Aims: To give researches on gastric interdigestive pressure activity, including gastrointestinal (GI) physiological motility recording method, data processing and analysis method, as well as to give reasonable interpretation on how to generate such gastric pressure activity. Study design: Basic application study. Place and Duration of Study: School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology (USST), between June 2010 and October 2011. Methodology: We introduced a telemetric method to get the gastric physiological pressure activity inside the GI tract and the general process for processing such gastric Migrating Motor Complex (MMC) pressure activity including the process of abnormal value removing, medians of five-three-Hanning (53H) weighted average smoothing, and the fluctuation frequency estimation. Results: Using the process of abnormal value removing, medians of five-three-Hanning (53H) weighted average smoothing, and the fluctuation frequency estimation, we well obtained gastric interdigestive pressure activity (MMC). Conclusion: The methods introduced in the paper including abnormal value removing, the 53H weighted average smoothing, and the fluctuation frequency estimation were helpful for researches on gastric interdigestive pressure activity.

An intelligent stimulator based on electromyography feature extraction / 生物医学工程学杂志

In order to improve the conventional stimulator with non-standard parameters and poor efficacy using the passive mode of the treatment, we developed an intelligent stimulator to combine biofeedback with functional electrical stimulation. Through the non-invasive measurement and feature extraction of electromyography signals, a value of root mean square can be obtained based on delta-sigma computational technique. In the newly designed stimulator, electromyography feature extraction and feedback control were used to intelligently control the rehabilitation treatment. Both bidirectional detection technologies for stimulated current and programmable interactive way using touchscreen were employed so that the treatment parameters can be accurately quantified and set up. The experiment showed that the design requirements were achieved.

The latest development of the localization for noninvasive monitoring capsule in gastrointestinal tract / 生物医学工程学杂志

The work of research and development of noninvasive monitoring system for human GI (gastrointestinal tract) has been very successful all over the world, and without questions, the system as such will extensively be applied in the future. However, the method for localization of the monitoring capsule in the system is not perfect. This paper reports the status quo of the research process for the capsule localization system, and analyzes their advantages and defects.

Localization system for electrical capsule based on permanent magnetic field / 生物医学工程学杂志

Localization system was designed based on analytic equation of permanent magnetic field to localize the swallowing electrical capsule in the gastrointestinal. Algorithm was presented and experiment was made. Two three-axis magnetism sensors were mounted in the capsule. The non linear equations set of sensor's output and capsule's position and attitude was created according to space position and attitude relationship model. The equations set was resolved with numerical method. Comparison between the calculation value and expected value showed that this method was feasible.

Telemetric Localization of Detecting Capsule in Gastrointestinal Tract / 航天医学与医学工程

Objective To develop a method for localizing a detecting capsule in the gastrointestinal tract.Methods A three-axis magnetic sensor was sealed in the detecting capsule.Three flat coils were fixed on patients' back.The coils were excited one by one to generate electromagnetic fields.The position and the orientation of the capsule could be determined by telemetering the signals from the magnetic sensor incorporated in the capsule.Results The telemetric localization system worked successfully.A localization model describing the relationship between the magnetic field strength and the position and orientation of the capsule,was correctly established basing on the principle of magnetic dipoles,and neural network algorithm was employed to solve a non-linear equation set.Conclusion The results showed that the localization method is feasible and the precision is higher than existing methods.The localization device can perform consecutive tracking and can be made into a portable type.After putting into practice,the device can also be used in food selection for astronauts by monitoring their gastrointestinal parameters in space.