Galvanic Skin Response Measurement and Analysis

Transcription

1 Galvanic Skin Response Measurement and Analysis A N Jayanthi 1, R.Nivedha 2, C.Vani 3 1 Associate professor, Department of Electronics and Communication Engineering, Sri Ramakrishna Institute of Technology, Coimbatore, India. 2,3 Students- Department of Electronics and Communication Engineering, Sri Ramakrishna Institute of Technology, Coimbatore, India, Abstract: Galvanic skin response measurement and analysis is used to measure skin resistance, skin conductance and stress level of human being. The mathematical manipulation can be implemented to measure these parameters skin resistance, skin conductance and stress level at various situations( i.e. listening music, mathematical calculations, breathing, watching movie, etc.,). The proposed technique is to interface the Arduino UNO controller (Atmega 328) with NI-Lab VIEW. Instead of using NI-DAQ, the Arduino can be used for data acquisition to decrease the cost. The NI-LIFA (LabVIEW Interface for Arduino) protocol is used to achieve this technique. The resistance of the skin can be acquired through the skin surface electrode (PCB type to increase the surface area). The resistance of the skin will vary depending upon the people condition. The acquired signal is signal conditioned, amplified and can be given to the Arduino controller. The GUI (Graphical User Interface) can be created in the NI-LabVIEW. The signal can be viewed in GUI. All the manipulation is designed in GUI. The GUI uses the protocol NI-VISA, formula node, filtering, Arduino toolkits, waveform viewing, NI- Sound and Vibration. Keywords: Galvanic skin resistance, conductance and stress, NI- lab VIEW, Arduino, NI-Sound and vibration. Introduction Electricity flows through an electrical circuit because of a difference in electrical pressure between the beginning and the end of a circuit. Electrical pressure or electromotive force (E) is measured in 12447

2 volts (V). The flow of electricity, called current (I), is measured in amperes (A) or amps for short. As electricity flows through the circuit, resistance to flow occurs. Electrical resistance (R) is measured in ohms (Ω). In a simple circuit of direct electrical current, the relationship between the electromotive force causing the electrical current, the resistance to flow of electricity and the resultant magnitude of the current is described by Ohm s Law. Galvanic Skin Response When a feeble electric current is steadily applied between two electrodes placed about an inch apart on the palm of the hand, the recorded electrical resistance between them, referred to as the galvanic skin resistance (GSR), varies in accordance with the emotional state of the subject. The physiological basis of the galvanic skin response is a change in autonomic tone, largely sympathetic, occurring in the skin and subcutaneous tissue in response to a change in the affective state of the subject. Changes in peripheral autonomic tone alter sweating and cutaneous blood flow, which in turn change GSR. As in the case of somatic sensory stimuli (e.g., pain, pressure, touch), changes in emotion elicit changes in peripheral autonomic tone and hence the galvanic skin response. A common example is the vasodilation of cutaneous blood vessels of the face (blushing) and increased sweating that often occurs in the emotional state of embarrassment. Principle It is used to measure the skin resistance, conductance and stress level in the body. The electrode senses the resistance of the skin from the body and gives output to op-amp. The skin resistance is inversely proportional to skin conductance. Objectives To become familiar with procedures for recording the galvanic skin response. To observe and record changes in respiratory rate, heart rate, and skin resistance associated with somatic and special sensory stimuli. To observe and record changes in respiratory rate, heart rate, and skin resistance associated with cognitive behavior and emotion. Although the recording procedures and measures used are similar to those that might be used in a real polygraph recording, 12448

3 this is not a lie detector test. All you will do here is record the Subject s physiological responses to certain questions. Some types of physiological responses are typically associated with lying, although even under the best conditions about one-third of innocent people fail lie detector tests. The best you can hope for here is to get a better understanding of how these types of procedures work. In stress level percentage we can analysis the stress level when listening to music and during math operations. The GSR electrode has to place on the fingers of the on hand for right prediction of stress level percentage. Existing System The Existing system was an iwork lab work graciously provided by DR. Paul Wagner and Dr. Tracy Wagner, Asst. professors, Washburn University, Topeka, KS. The system works with IXTA data acquisition unit, IXTA power supply and Labscribe2 software. To improve human-computer interaction (HCI), computers need to recognize and respond properly to their user s emotional state [1]. This is a fundamental application of affective computing, which relates to, arises from, or deliberately influences emotion. As a first step to a system that recognizes emotions individual users, this research focuses on how emotional experiences are expressed in six parameters (i.e., mean, absolute deviation, standard deviation, variance, skewness, and kurtosis) of not baseline-corrected physiological measurements of the galvanic skin response (GSR) and of three electromyography signals: frontalis (EMG1), corrugator supercilii (EMG2), and zygomaticus major (EMG3). The current paper discusses the emotions people can experience and their expression in and detection through psycho-physiological measures. The affective wearables are introduced in which the proposed apparatus for the measurement of the psychophysiological signals can be embedded. Proposed System In the proposed system the IXTA setup with Labscribe2 software is replaced by interfacing Arduino with LabVIEW

4 Circuit The system uses switched mode power supply 230V-12V (step down transformer) and 12V-5V (rectifier), the linear regulator (LM317) and a filter. The dual OP-AMP used here acts as a voltage divider circuit to calculate GSR to the electrode. The input from the electrode is given to the OP-AMP where it is amplified and given to Arduino UNO port A0 and connected to the computer or laptop through USB. At the same time LIFA (LabVIEW Interface for Arduino) and the analog signal is received from electrode. The system here is a real time continuous hence no resetting is required. GSR can be measured while playing songs, fast breathing and arithmetic calculations. By this conductance, resistance, stress level, threshold comparison are calculated. GSR, Resistance, Conductance waveforms Threshold waveform 12450

5 Stress level waveform The main novelty in this proposed system is interfacing LABVIEW with Arduino. When the work is done fully with Arduino kit the cost is higher and NI-DAQ in LABVIEW is also costly. Hence we replace NI-DAQ in LABVIEW by Arduino. The proposed system can also be used in computer that does not have a LabVIEW by converting it into an.exe file with help of application builder in LABVIEW thus creating a package for friendly usage. This system provides better solution and easy data saving. Reference 1. Joyce H.D.M. Westerink, Egon L.Van Den Broek, Marleen H. Schut, Jan Van Herk and Kees Tuinenbreijer, Computing emotion awareness through galvanic skin response and facial electromyography in International Journal of Springer,2008,page no: J. Ferreira and L. Alvarez, R Buendia, D Ayllon, C. Llerena, R Gil-Pita and F Seoane, Bioimpedance based wearable measurement instrumentation for studying the autonomic nerve system response to stressful working conditions in Journal of Physics: Conference series 434(2013) Licensed by IOP Publishing Ltd. 3. Nicholas L.Carnagey, Craig A. Anderson, Brad J. Bushman, The effect of video game violence on physiological desensitization to reallife violence in Journal of Experimental Social Psychology 43(2007) page no: Nargess Nourbaksh, Yang Wang, Fang Chen and Rafael A. Calvo, Using galvanic skin response for cognitive load measurement in arithmetic and reading tasks in OZCHI 12 Nov 26-30,2012 Melbourne, Australia. 5. Ming-Zher, Poh,Nicholas C.Swenson, and Rosalind W.Picard, A Wearable Sensor for unobtrusive, long- term assessment of electro dermal activity in IEEE transactions on bio-medical engineering,vol. 57,NO.5, may

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