The impact of active electrode guard layer in capacitive measurements of biosignals

Bednar, Tadeas; Babušiak, Branko; Šmondrk, Maroš; Čáp, Ivo; Borik, Štefan

doi:10.1016/j.measurement.2020.108740

Cited by 7 publications

(7 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Figure 3 a represents the schematic and layers disposition of AE Figure 3 b shows the physical construction of AE with a sensing area of 16 cm 2 . The impact of the active electrode guard layer in capacitively coupled measurements was already presented by Bednar et al [ 16 ]. In this work, the improvement of the AE’s transfer characteristic was confirmed due to the use of the guard layer.…”

Section: Methodsmentioning

confidence: 88%

“…This fact is caused by local differences in the thickness and composition of dielectric material (clothes) and the electrode’s pressure. These differences lead to the different gain of each electrode [ 16 ]. According to Peng et al [ 29 ], the differences between the input AE capacitances can be doubled during the measurement.…”

Section: Resultsmentioning

confidence: 99%

“…As we can see, the C pi parasitic capacitance decreases the gain of the active electrode, and the effect of the parasitic capacitance has to be eliminated. A few commonly used methods for parasitic capacitance cancelation exist, for example, neutralization circuit or using of guard layer [ 13 , 14 , 15 , 16 ]. When using the assumption of neglected parasitic capacitance, the transfer characteristic can be determined as

…”

Section: Methodsmentioning

confidence: 99%

“…The same electrode was presented and analyzed in detail by Bednar et al [ 16 ]. Figure 3 a represents the schematic and layers disposition of AE Figure 3 b shows the physical construction of AE with a sensing area of 16 cm 2 .…”

Section: Methodsmentioning

confidence: 99%

See 3 more Smart Citations

Common-Mode Voltage Reduction in Capacitive Sensing of Biosignal Using Capacitive Grounding and DRL Electrode

Bednar

Babušiak

Labuda

et al. 2021

Sensors

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Section: Methodsmentioning

confidence: 88%

Section: Resultsmentioning

confidence: 99%

…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Common-Mode Voltage Reduction in Capacitive Sensing of Biosignal Using Capacitive Grounding and DRL Electrode

Bednar

Babušiak

Labuda

et al. 2021

Sensors

Self Cite

View full text Add to dashboard Cite

show abstract

“…The output of the FVF (i.e., sensed voltage) was fed back to the driven shield layer via a 150-Ω resistor. The driven shield layer performs not only as a shield but also as a protector against current leakage from the sensing layer to the GND layer, decreasing the stray capacitance between the sensing and GND layers and increasing the common-mode rejection ratio (CMRR) [ 51 ]. Furthermore, the driven shield layer is known to protect the sensing layer from undesirable current caused by moving artifacts and electrostatic disturbances, thereby improving the artifact tolerance [ 49 , 50 ].…”

Section: Methodsmentioning

confidence: 99%

Non-Contact Measurements of Electrocardiogram and Cough-Associated Electromyogram from the Neck Using In-Pillow Common Cloth Electrodes: A Proof-of-Concept Study

Takano

Ishigami

Ueno

2021

Sensors

View full text Add to dashboard Cite

Asthma and chronic obstructive pulmonary disease are associated with nocturnal cough and changes in heart rate. In this work, the authors propose a proof-of-concept non-contact system for performing capacitive electrocardiogram (cECG) and cough-associated capacitive electromyogram (cEMG) measurements using cloth electrodes under a pillowcase. Two electrodes were located along with the approximate vector of lead II ECG and were used for both cECG and cEMG measurements. A signature voltage follower was introduced after each electrode to detect biopotentials with amplitudes of approximately 100 µV. A bootstrapping technique and nonlinear electrical component were combined and implemented in the voltage follower to attain a high input impedance and rapid static discharge. The measurement system was evaluated in a laboratory experiment for seven adult males and one female (average age: 22.5 ± 1.3 yr). The accuracy of R-wave detection for 2-min resting periods was 100% in six subjects, with an overall average of 87.5% ± 30.0%. Clearly visible cEMGs were obtained for each cough motion for all subjects, synchronized with reference EMGs from submental muscle. Although there remains room for improvement in practical use, the proposed system is promising for unobtrusive detection of heart rate and cough over a prolonged period of time.

show abstract

Seat to beat: Novel capacitive ECG integration for in-car cardiovascular measurement

Kafková,

Babušiak,

Pirník

et al. 2024

Measurement

View full text Add to dashboard Cite

The impact of active electrode guard layer in capacitive measurements of biosignals

Cited by 7 publications

References 32 publications

Common-Mode Voltage Reduction in Capacitive Sensing of Biosignal Using Capacitive Grounding and DRL Electrode

Common-Mode Voltage Reduction in Capacitive Sensing of Biosignal Using Capacitive Grounding and DRL Electrode

Non-Contact Measurements of Electrocardiogram and Cough-Associated Electromyogram from the Neck Using In-Pillow Common Cloth Electrodes: A Proof-of-Concept Study

Seat to beat: Novel capacitive ECG integration for in-car cardiovascular measurement

Contact Info

Product

Resources

About