Authors:
Luca Maggi
1
;
Luca Piccini
1
;
Sergio Parini
1
;
Giuseppe Andreoni
1
and
Guido Panfili
2
Affiliations:
1
Politecnico di Milano, Italy
;
2
SXT – Sistemi per telemedicina srl., Italy
Keyword(s):
Wearable device, Brain Computer Interface, Amplifier, Signal Conditioning, Offset Recovery, Low Voltage Amplifier, Band Pass Filtering, ECG amplifier, EEG amplifier.
Related
Ontology
Subjects/Areas/Topics:
Applications and Services
;
Biomedical Engineering
;
Biomedical Signal Processing
;
Computer Vision, Visualization and Computer Graphics
;
Devices
;
Health Information Systems
;
Human-Computer Interaction
;
Medical Image Detection, Acquisition, Analysis and Processing
;
Physiological Computing Systems
;
Wearable Sensors and Systems
Abstract:
The here presented work illustrates a novel circuit topology for the conditioning of biomedical signals. The system is composed of an amplification chain and relies on a double feedback path which assures the stability of the system, regardless of the amplification block gain and the order of the low-pass filter settings. During the normal operation, the offset recovery circuit has a linear transfer function, when it detects a saturation of the amplifier, it automatically switches to the fast recovery mode and restores the baseline in few milliseconds. The proposed configuration has been developed in order to make wearable biosignal acquisition devices more robust, simpler and smaller. Thanks to the used AC coupling method, very low high-pass cut-off frequencies, can be achieved even using small valued passive components with advantages in terms of circuit bulkiness. The noise rejection filter between the pre-amplification and the amplification stages eliminates the out-of-band noise
before the amplification reducing the possibility of having clipping noise and minimizing the dynamic power consumption. The presented topology is currently used in a prototypal EEG acquisition device in a Brain Computer Interface (BCI) system, and in a commercial polygraph which will be soon certificated for clinical use.
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