Implantable intrabody communication (IBC) is a method that enables low-power, high-security communication between implanted in-body devices that could track biomedical signals and an on-body receiver by using the human body as a communication medium. As the human body consists of various tissues that each have different conductivity, this paper explores the effects of the conductivity of the communication medium on the channel gain over a wide frequency range from 10 MHz up to 300 MHz through the measurements and two models: an electrical circuit model and a FEM simulation model. Measurements are conducted using a liquid phantom with varying conductivity values from 0 S/m up to 1 S/m, covering most human tissues in the frequency range of interest. The circuit and FEM models are designed to mimic the measurement setup in order to verify the measurement results. Results show that the circuit model predicts the communication channel characteristics well at lower frequencies but cannot account for the influence of the measurement setup at higher frequencies. The influence of wire inductances, which can cause a resonant behavior when measuring at frequencies above 100 MHz, was observed using the FEM model. The results also show that the higher the conductivity of the tissue in which the device is implanted, the lower the gain of the signal, with the difference in gain being more prominent when capacitive termination with a high-impedance load is used instead of low-impedance termination. These findings provide valuable insight for selecting the appropriate interface (low-impedance vs. high-impedance termination) across specific frequency ranges for in-body to on-body (IB2OB) communication devices, while illustrating the effect of tissue conductivity on an IBC channel, thereby supporting the optimized design and implementation of reliable IB2OB communication systems.

Implantable capacitive intrabody communication is a wireless communication method that utilizes capacitive coupling as a way for the implants to communicate between each other as well as with the devices that are placed on the body. Since there are several possible configurations, such as in-body to on-body (IB2OB) communication and on-body to in-body (OB2IB) communication, it is important to investigate how the communication channel behaves for each configuration. Therefore, in this paper, a two-layer 3D model of the upper part of the leg between the knee and ankle has been created for the measurement purposes. The phantom consists of an outer layer that mimics the fat tissue with a very low conductivity and an inner layer that has a conductivity like the muscle. During the measurements, one pair of electrodes with an insulated ground electrode was inserted into the muscle layer and connected to the transmitter, while the other pair of the electrodes was placed on the phantom and connected to the receiver (IB2OB). After the IB2OB measurements were completed, the transmitter and receiver devices were swapped to measure the OB2IB scenario. The results show that changes in the configuration lead to negligible difference in the measurement results, i.e. the system is reciprocal. Moreover, a high-pass profile was observed for the frequency range from 100 kHz to 84 MHz.

Implantable capacitive coupling (CC) intrabody communication (IBC) provides a method of communication for in-body devices to communicate not only between each other, but also with an on-body device and vice versa, using a low power, highly secure way of communication. However, to be able to realize such systems, it is important to understand the characteristics of a communication channel in an implantable CC. Therefore, in this paper, measurements of the received power in an implantable CC IBC system were performed on a liquid phantom with the same conductivity as a muscle tissue, using proprietary developed battery-powered devices (transmitter and receiver) for different measurement scenarios. The transmitter was placed inside the phantom while the receiver was placed outside of the phantom and vice versa, and the type of electrode used was changed. The results showcase the importance of minimizing the bandpass profile effect caused by the long cables. It is also shown that insulating the ground electrode affects the measured attenuation by about 6 dBm.

With the change of modern lifestyle, the number of people living a sedentary life is increasing, which can lead to sustained tension in the low back muscles, which in turn can cause lumbar muscle strain and even low back pain. Measuring low back muscle fatigue in real time could help prevent and rehabilitate low back pain and improve the health of sedentary individuals. In this paper we aim to estimate muscle fatigue of low back muscles in vivo using electrical impedance myography (EIM). EIM measurements were performed using a proprietary impedance measuring device and the commercial Imp <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TM</sup> SFB7 human body composition analyzer. Impedances measured with both devices showed correlation greater than 0.99 and a linear decreasing trend with duration of fatigue contraction. The impedance of the lumbar muscles measured at the end of the experiment when fatigue occurred (240 s) was 16±2 Ω lower than the impedance measured at the beginning of the experiment (0 s). The measured resistance decreased by approximately 13 % and the reactance increased by approximately 8.5 % during low back muscle contraction, indicating a sufficient sensitivity of the muscle impedance graph in detecting low back muscle fatigue. These results contribute to the research of EIM assessment of low back muscle fatigue and provide valuable guidance for additional research.

This paper is an introduction to underlying mechanisms and the current state of technologies in the field of intrabody communication (IBC).IBC technologies utilize the human body as a communication channel to achieve communication between different devices that can be positioned inside or on the surface of the body.Current developments in the field of mobile gadgets, smartwatches and medical devices make this field of particular interest due to very low energy expenditure, security, and ability to protect private data.Since there are multiple subfields in the field of IBC technologies, this paper will focus on summarizing the principles of work for galvanic coupling and capacitive coupling and compare the tradeoffs of using one approach over the other.

The embedded system STM32F4 microcontroller primary use is accomplishing the independent workstation for EEG digital signal processing. Signal input is achieved through differential amplifier and analog-digital converter ADS1252. Furthermore, the EEG signal is processed through Fast Fourier Transform algorithm and substantially categorized according to its frequency. The end goal is achieving a clear display of the results on embedded 2.4-inch LCD display through usage of bars and text.