Apparatus for electrodermal activity measurement with current compensation
Inventors
TOGNETTI, SIMONE • CENCI, IVAN • RESNATI, DANIELE • GARBARINO, MAURIZIO • LAI, MATTEO
Assignees
Publication Number
US-11766187-B2
Publication Date
2023-09-26
Expiration Date
2034-03-17
Interested in licensing this patent?
MTEC can help explore whether this patent might be available for licensing for your application.
Abstract
An apparatus for measuring electrodermal activity can include a first electrode in contact with a first portion and a second electrode in contact with a second portion of a stratum corneum, and in electronic communication with the second electrode through the stratum corneum. A processing module is electrically coupled to the first electrode and the second electrode and is operable to (a) bias the first electrode at a first voltage V+ and the second electrode at a second voltage V− (b) measure a current flowing between the first electrode and the second electrode, the current corresponding to the conductance of the stratum corneum, (c) subtract a compensation current from the measured current (d) measure a resulting current producing an amplified output voltage (e) measure a conductance of the stratum corneum, and (f) adjust at least one of the first voltage, the second voltage and the compensation current to desaturate the output voltage.
Core Innovation
The invention relates to apparatus, systems, and methods for measuring electrodermal activity, particularly using wearable devices that include at least two electrodes contacting different portions of the stratum corneum of the skin. The apparatus includes a processing module that biases the electrodes at different voltages, measures the current flowing between the electrodes corresponding to the skin's conductance, and dynamically adjusts a compensation current and the electrode voltages to desaturate the output voltage. This allows accurate measurement of both tonic and phasic levels of skin conductance over a wide range while reducing electrode electrolysis.
The problem being solved arises from challenges in measuring electrodermal activity reliably and with high resolution. Human skin conductance varies widely due to physiological and environmental factors, and conventional sensors face difficulties: DC current sensors risk electrolysis and corrosion of electrodes, whereas AC sensors lack resolution for phasic signals. Furthermore, the wide dynamic range of tonic conductance and fast changes in phasic conductance complicate measurement. The invention addresses the need for reliable, repeatable skin conductance measurements that handle wide signal ranges, reduce electrode corrosion, and enable wearable real-time monitoring.
Claims Coverage
The patent includes multiple independent claims covering apparatuses that feature compensation circuitry and processing for adaptive conductance measurement and well-being analysis using electrodermal and heart beat data.
Apparatus for adaptive skin conductance measurement
Includes two electrodes contacting tissue, compensation circuitry generating a compensation voltage and current, and processing circuitry that applies voltage between electrodes, measures current, adjusts the current using compensation current to desaturate output voltage, thereby enabling measurement of phasic and tonic conductance levels.
Wearable device combining electrodermal and heart beat sensors
Electrodermal sensor with two electrodes and a heart beat sensor collect data from the user. Processing circuitry applies voltage across electrodes, measures and compensates current to maintain output voltage within a predefined range, measures heart rate or variability, and determines tonic conductance proportional to adjusted compensation current or voltage.
The independent claims principally cover an apparatus and a wearable device integrating compensation circuitry to dynamically adjust measurement currents, retain output signals within measurable bounds, reduce electrode electrolysis via polarity reversal, and combine electrodermal conductance sensing with heart rate data to determine physiological well-being.
Stated Advantages
Capability to measure electrodermal activity over a wide range that covers the entire range of expected tonic level conductances.
High resolution measurement of phasic level conductances.
Reduction in electrolysis of sensing electrodes by polarity reversal to prevent corrosion and skin irritation.
Real-time electrodermal activity measurement through integration in wearable devices, such as wrist bands.
Documented Applications
Wearable devices for measuring electrodermal activity of the skin to monitor autonomic nervous system activity and physiological status.
Monitoring users' mental and physical well-being via electrodermal activity signals indicative of tonic and phasic conductance levels.
Wearable devices combining electrodermal activity sensors and heart beat sensors to measure heart rate variability and determine a well-being index (WBI).
Real-time physiological profiling for stress, relaxation, and health monitoring through continuous skin conductance and heart rate measurements.
Interested in licensing this patent?