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.

In this work, we present a novel portable, flexible and easy-to-use experimental setup for investigating salinity- based information transmission in microfluidic channels. At the receiver, the different salinity-levels are detected by a customized electronic circuit, which measures electrical conductivity via electrodes in the microfluidic channel. We provide a detailed de- scription of the setup, including the microfluidic chip fabrication. Moreover, we develop a rigorous mathematical model of each testbed component and an end-to-end model of the system, which we have verified through experiments. Finally, we analyzed the error performance of the setup using optimum and sub-optimum detection algorithms, such as the Viterbi algorithm and threshold detection.

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.

In order to enable molecular communication on macroscopic distances without a moving medium, the model of diffusion-based information transmission with a large number of relays suspended in the medium, hence at random positions, is proposed. With an increasing number of relays, the stochastic variations approach zero and the system exhibits a quasi-deterministic behavior. Furthermore, the transmission time becomes inversely proportional to the number of relays and the impulse response independent of the channel length. Thus, the model describes a wave-like propagation, which is fundamentally different from the established flow- and diffusion-based approaches in molecular communication.

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.

Molecular Communication provides a solution for scenarios where conventional technologies for data transmission are not feasible due to energy or size constraints. The development and characterisation of sensor devices for information particles as receivers is an essential step to realising Molecular Communication setups. In this work we will present a new device for sensing of magnetic nanoparticles using a capacitor to detect changes in permittivity. The sensor was evaluated regarding sensitivity and a data transmission scenario in a testbed and compared to an inductive sensor. The new sensor device has a significantly higher sensitivity than the reference sensor, allowing for the use of less information particles when transmitting data. However, the impulse response is wider as magnetic nanoparticles are held in the electromagnetic field of the receiver's capacitor.

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.

Droplet-based microfluidics show a large potential for lab-on-chip applications and new data transmission scenarios. Microfluidic chips contain channels in the submillimeter range allowing for flow of droplets. In a previous contribution, a new sensor design for droplet size and colour detection, consisting of an infrared and a colour sensor, was presented and a first proof-of-concept was shown. In this work, an in-depth analysis of both concepts is presented. In particular, we show that a high precision can be achieved when using the sensor to measure droplet sizes while using video processing software as reference. Furthermore, a colour alphabet consisting of 126 individual values is transmitted and detected using a machine learning model. The high specificity of achieved colour measurement allows both for colour coded data transmission scenarios and the analysis of colour reagents in lab-on-chip applications.