Testbeds play an essential role in the development of real-life molecular communication applications and experimental validation of communication channel models. Although some testbed concepts have been published in recent years, very few setups are inherently suitable for biomedical applications. Furthermore, systematic experimental data of a wide parameter field for molecular communication is scarce and often difficult to generate. In this work, a biocompatible testbed for molecular communication with magnetic nanoparticles is used to investigate a series of transmission channel parameters. The observed results are discussed in the context of a laminar flow channel. All experimental data regarding the parameter studies as well as an additional data set for a large binary transmission sequence is provided as a supplement to this publication. The data is available on a public server to allow for further use by other researchers.

This article presents a comparison of 4 different types of rectifier circuits for piezoelectric energy harvesting. Energy is harvested from multiple piezoelectric elements embedded in an in?sole while simultaneously collecting gait information of the subject wearing it. The study is based on an asymmetric signal generated while walking and the harvested energy is utilized to operate a system under a fixed electrical load. The influence of back-up battery and insole design optimization on the accuracy of collected information is taken into consideration. A comprehensive approach for shoe insole application based on simultaneous piezoelectric sensing and energy harvesting is presented in this work.

Magnetic nanoparticles offer numerous promising biomedical applications, e. g. magnetic drug targeting. Here, magnetic drug carriers inside the human body are directed towards tumorous tissue by an external magnetic field. However, the success of the treatment strongly depends on the amount of drug carriers, reaching the desired tumor region. This steering process is still an open research topic. In this paper, the previous study of a linear Halbach array is extended by an additional Halbach array with different magnetization angles between two adjacent magnets and investigated numerically using COMSOL Multiphysics. The Halbach arrays are arranged with permanent magnets and generate a relatively large region of a moderately homogeneous, high magnetic field while having a strong gradient. This results in a strong magnetic force, trapping many particles at the magnets. Afterwards, to avoid particle agglomeration, the Halbach array is flipped to its weak side. Therefore, the magnetic flux density, its gradient and the resulting magnetic force are computed for the different Halbach arrays with different constellations of magnetization directions. Since the calculation of the gradient can lead to high errors due to the used mesh in Comsol, the gradient was derived analytically by investigating two different fitting functions. Overall, the array with a 90° shifted magnetization performs best, changing the magnetic sides of the array easily and deflecting more particles. Besides, the results revealed that the magnetic force dominates directly underneath the magnets compared to the other existing forces on the SPIONS. Summarized, the results depict that the magnetic force and, thus, the region where the particles are able to get washed out, can be adjusted using low-cost permanent magnets.

Although the concept of engineered molecular communication has been around for quite some time, practical approaches with truly biocompatible setups are still scarce. However, molecular communication has a large potential in future medical applications and may be a solution to size constraints of antenna based transmission systems. In this work we therefore present a testbed using biocompatible magnetic nanoparticles. Based on previous work, all testbed components have been improved regarding performance and size, making a large step forwards regarding miniaturisation and a data transmission approach. In addition, a setup for localised twodimensional sensing of magnetic nanoparticles is presented. All improvements are evaluated individually and combined to achieve a net data rate of more than 6 bit/s, significantly higher than any other comparable biocompatible setup.

Capsule endoscopy is a promising diagnostic tool for the entire gastrointestinal tract. Since a patient swallows the capsules, their size must be sufficiently small. The principal built-in components are cameras, silver-oxide batteries, light emitting diodes, and an antenna for transmitting the video. For diagnosis and treatment, the precise localization of the capsules for specific video frames is required. Recently, static magnetic localization of these  apsules with an integrated permanent magnet showed promising results. However, in the state-of-the-art, relatively large magnets compared to the small capsules were used. Therefore, in this extended paper, the localization performance of a recently proposed optimized differential static magnetic localization method for different-sized discs and ring magnets was evaluated. The ring magnets were designed for integration with the two batteries of commercial capsules. The magnets were evaluated in static and dynamic scenarios to evaluate the performance of the method in a patient’s daily life. It was revealed that the mean position and orientation errors did not exceed 5 mm and 4°, respectively, for all applied magnets except for the 1.5 mm and 3 mm long disc magnets. Moreover, the results indicated that the ferromagnetic batteries of capsule endoscopes increase the localization performance when they are centered within a diametrical ring magnet. Overall, it was revealed that the localization performance of the optimized differential method is significantly better than the state-of-the-art even when the magnet volume is significantly reduced compared to previous work. Therefore, it was concluded that a 5 mm long disc magnet or a ring magnet are excellent candidates for integration into a commercial capsule for magnetic localization and yield the advantage of being passive magnetic sources.

Wireless capsule endoscopy is an established medical application for the examination of the gastrointestinal tract. However, the robust and precise localization of these capsules is still in need of further scientific investigation. This paper presents an innovative differential magnetic localization method for capsule endoscopy to prevent interference caused by the geomagnetic field. The effect of changing the orientation of the capsule on the localization process was also examined. Simulations using COMSOL Multiphysics with the superimposed geomagnetic field were performed. The Levenberg–Marquardt algorithm was applied in MATLAB to estimate the position and orientation of the capsule. Comparing the proposed differential method with the absolute magnetic localization method under ideal conditions, the mean position and orientation errors were reduced by three orders in magnitude to less than 0.1 mm and 0.1 ° respectively. Even if sensor non-idealities are considered, the simulationbased results reveal that our proposed method is competitive with state-of-the-art geomagnetic compensation methods for static magnetic localization of capsule endoscopes.The achieved localization accuracy by applying the differential method is not dependent on the rotation of the localization system relative to the geomagnetic flux density under the made assumptions and the impact of the magnet orientation is neglectable. It is concluded that the proposed method is capable of preventing all interference whose components are approximately equal at all sensors with identical orientation.

Differences in contact impedance of the ECG measurement electrodes lead to asymmetries of the signal paths and thus result in reduced common-mode rejection and artifacts. Here, the imbalance of contact impedance is investigated for different types of electrodes with capacitive coupling in terms of static imbalance as well as dynamic variation during body movement. Flexible and incompressible materials like conductive foam and fabric showed the best overall performance. The negative effect of rigidity can partly be compensated by adding conducting foam, while soft materials can profit from an increase of electrode area.

A document by Doaa Ahmed . Click on the document to view its contents.

A document by Doaa Ahmed . Click on the document to view its contents.

This manuscript was published at 08.10.2021 by the IEEE Transactions on Magnetics. Regarding Mr. Sivo’s Email, the accepted version of the manuscript is now uploaded which also includes the corresponding DOI.

Molecular communication uses molecules or other nanoscale particles to transmit data in scenarios where conventional communication techniques are not feasible. In previous work a testbed using superparamagnetic iron oxide nanoparticles (SPIONs) as information carriers in a fluid transmission channel with constant background flow was proposed. The SPIONs are detected at a receiver as change of a coils inductance. We now improve the testbed by using a piezoelectric micropump as transmitter, making amplitude modulation (AM) with di?erent injection volumes possible. Machine learning is employed at the receiver to di?erentiate between six di?erent amplitude levels and grey code is used to reduce bit errors. With AM and the designed coding scheme, the achievable e?ective data rate was doubled to 4.45 bit/s.

Testbeds are required to assess concepts and devices in the context of molecular communication. These allow the observation of real-life phenomena in a controlled environment and therefore present the basis of future work. A testbed using superparamagnetic iron oxide nanoparticles (SPIONs) as information carriers was constructed with regard to this context and requires a sensitive receiver for the detection of SPIONs. This paper focusses on the comparison between a newly presented device (inductance sensor), a previously constructed SPION sensor (resonance bridge), and a commercial susceptometer as reference. The new inductance sensor is intended to improve on a low sensitivity achieved with the previous device and restrictions with respect to sample rate and measurement aperture encountered with the susceptometer. The signal-to-noise ratio (SNR) for each device is assessed at a variety of SPION concentrations. Furthermore, the sensors bit error rates (BER) for a random bit sequence are determined. The results show the device based on an inductance sensor to be the most promising for further investigation as values both for BER and SNR exceed those of the resonance bridge while providing a su?ciently high sample rate. On average the SNR of the new device is 13 dB higher while the BER for the worst transmission scenario is 9% lower. The commercial susceptometer, although returning the highest SNR, lacks adaptability for the given use case.