A capacitive measurement of the biosignals is a very comfortable and unobtrusive way suitable for long-term and wearable monitoring of health conditions. This type of sensing is very susceptible to noise from the surroundings. One of the main noise sources is power-line noise, which acts as a common-mode voltage at the input terminals of the acquisition unit. The origin and methods of noise reduction are described on electric models. Two methods of noise removal are modeled and experimentally verified in the paper. The first method uses a passive capacitive grounding electrode, and the second uses an active capacitive Driven Right Leg (DRL) electrode. The effect of grounding electrode size on noise suppression is experimentally investigated. The increasing electrode area reduces power-line noise: the power of power-line frequency within the measured signal is 70.96 dB, 59.13 dB, and 43.44 dB for a grounding electrode area of 1650 cm², 3300 cm², and 4950 cm², respectively. The capacitive DRL electrode shows better efficiency in common-mode noise rejection than the grounding electrode. When using an electrode area of 1650 cm², the DRL achieved 46.3 dB better attenuation than the grounding electrode at power-line frequency. In contrast to the grounding electrode, the DRL electrode reduces a capacitive measurement system’s financial costs due to the smaller electrode area made of the costly conductive textile.

Microvascular function, particularly of the plantar foot, reflects overall vascular health and is influenced by physiological oscillators such as heart rate, respiratory, myogenic, and neurogenic rhythms. Slow deep breathing modulates autonomic nervous system activity and affects peripheral microcirculation. This study investigates the effects of slow deep breathing on plantar foot perfusion using photoplethysmography imaging (PPGI). Twenty healthy young adults participated in a four-stage protocol: baseline, deep breathing test (DBT), and two recovery stages (REST1 and REST2). PPGI was used to measure changes in plantar foot perfusion, focusing on energy, amplitude, and phase synchronization within frequency bands corresponding to key physiological oscillators. Time-frequency analyses and advanced signal processing were applied to assess these parameters. Significant increases in energy were observed in all frequency bands during DBT, with slow frequency oscillators (SFOs) maintaining elevated activity up to 5 min after DBT. Amplitude analysis revealed a significant decrease in the first and second harmonic components of the heart rate signals during DBT. Phase synchronization between medial and lateral foot regions improved for respiratory, myogenic, and neurogenic frequency bands during DBT, with myogenic synchronization persisting for up to 2.5 min after DBT. Slow deep breathing enhances microvascular perfusion and synchronizes autonomic oscillators in healthy individuals. PPGI proved effective in capturing these dynamics, indicating its potential as a non-invasive tool for assessing autonomic and microvascular function. Future research should explore its applicability in detecting early autonomic or vascular dysfunction in clinical populations.

Magnetic fields play a crucial role in modern science and technology - yet precise and accessible tools for their measurement remain limited, especially for small laboratories, educators, or independent researchers. This paper introduces a novel, open-source magnetic field measurement system based on three-axis sensors for monitoring both direct and extremely low frequency magnetic fields. The device features a modular hardware design centered around a custom PCB, enabling flexible analog filtering, Bluetooth data transmission, and offline LCD visualization. By combining the MC858 and MPU9250 sensors with precise analog signal conditioning and a 12-bit ADC, the system ensures reliable detection of magnetic fields including the 50 Hz mains frequency and its harmonics. To verify the functionality of the device, experimental measurements were conducted inside a Faraday cage using a common hair dryer placed at distances of 1 cm and 3 cm from the sensors as a source of electromagnetic field. Frequency analysis confirmed reliable detection of the dominant 50 Hz component and its harmonics, as well as the system’s ability to distinguish changes in field intensity based on distance and operating state of the source device.

The comfortable, accurate, and long-term monitoring in biomedical applications is assigned significant interest. The measurement by textile electrodes satisfies these properties, and for that reason, they are increasingly employed in medical and non-medical applications to measure signals such as electrocardiographic (ECG), electromyographic (EMG), or electroencephalographic (EEG) signals. This paper investigates three conductive textile materials with two different surface sizes and Ag/AgCl electrodes regarding skin-electrode interface impedance frequency dependency. One textile material is selected and tested for the ECG and EMG signal measurement based on the impedance measurement results. The resulting data are also compared with records measured using Ag/AgCl electrodes.

This paper describes a distance measurement process, tracking the environment, and determining the presence of space obstacles. The ultrasonic module HC-SR04 is used to measure the distance. This module is complemented by a servo motor, which allows gradual monitoring of the surroundings. The way of signaling obstacles in the space is realized via the vibrating motor. All information about the measured distance is then transmitted to the computer via the Bluetooth module, where is created graphical user interface in the MATLAB program. The system is designed to enable orientation in space for people with visual impairments.

This paper describes a system design for testing implantable devices, namely pacemakers, that measures selected pacemaker parameters to indicate their proper functionality or potential malfunction. The resulting signals are interpreted and plotted using the programming interface of MATLAB. The efficiency of the resulting wiring is tested on real pacemakers and compared to the values of commercial programmers. The system is designed for easy and universal measurement of pacemaker parameters for learning purposes in the teaching process.