Objective of the project
Development of a prototype of a mobile device for monitoring the biological profile of a man.
Tools and materials
(1) The board Intel Galileo
(2) Mobile neurointerface
(3) Measuring device E14-440
(4) Microphone cable
(5) The voltage regulator TL431
(6) Operational Amplifiers: OP 97, TLC272, AD620
(7) The capacitors + resistance
(8) Battery compartment + batteries
(9) Prototyping board jumpers
Step 1: Step 1: Production of Active Electrodes
Stages of the project
Electrode EEG - the sensor, through which the diversion of bioelectric activity of different brain structures. The electrode is fixed to the head by means of special rubber bands or helmets. In medical practice commonly used the so-called "wet" electrodes - electrode contact with the skin surface through a sponge ball or gauze pad soaked in saline, or through a special paste. In our project, we use "dry" active electrodes. Huge-electrode resistance of the sensor on the scalp, is connected to the input of the amplifier whose resistance is small relative to the resistance skin-electrode, resulting in failure of the circuit:
the useful signal is drowned in the noise. To get rid of used matching follower whose input impedance tends to infinity, and the output to zero. Driving Repeater is as follows: As an op amp to build a repeater used TLC272. Here screen (copper braid wire) must be connected to the circuit to zero: The project was made of three types of active electrodes: (1) "pill" for the connection of standard ECG electrodes, (2) the type of needle electrodes "comb" head with metal (3) needle electrodes "comb" type graphene head. A photo In addition, was made "reference" electrode - electrode measured with respect to which the value of biopotential oscillations occurring on the other (working) electrode:
Step 2: Step 2: Production of the Active Electrode Power Supply
For active electrode power scheme is used: The circuit is assembled on the breadboard. We have removed the large capacitors C1 and C2 in the 470 uF.
Step 3: Step 3: Testing of the Active Electrodes
To test the active electrode measuring device used processing analog and digital information E14-440 of L-Card: Two active electrode is removed with frontal EEG signals ( "button" electrode) and occipital ( "needle" electrode) parts of the head. The signals are digitized by the ADC E14-440 and transferred to a laptop using a USB cable. On the laptop digitized signals are visualized in the program PowerGraph 3.3. EEG signals from the frontal and occipital parts of the head, rendered PowerGraph program can be found here.
Step 4: Step 4: Connecting the Active Electrode to the Mobile Neurointerface
The active electrodes are prepared. Connect them to the mobile neurointerface. Neurointerface is in testing and tuning stage (this is another project). The project was able to use only one of the four channels of EEG signals pickup. Instead BT channel to transmit data to a laptop using a USB channel. USB data is transmitted on a channel in a text format at the speed 460800 (bits / sec). One line contains four numbers - the next values of the four channel signals. Here's how it looks on the putty terminal screen:
Step 5: Step 5. Construction of the Prototype Bio Signal Acquisition and Processing System Based on the Active Electrodes, Mobile Neurointerface and Board Intel Galileo
At the beginning of the project planned to establish a bio-signal acquisition and processing system that implements the following algorithm works: (1) Electric signals are removed from human body via the active electrodes and are transmitted in analogue form to the mobile neyrointerfeys input. (2) Mobile neyrointerfeys amplifies the analog signals from the four channels, digitizes them, forms a bio-data packet and transmits it over the channel to BT Intel Galileo charge. (3) Intel Galileo performs digital signal processing (signal filtering and recovering the alpha and beta rhythms), and transmits the results of processing (rhythm) in a laptop WiFi channel. (4) On the laptop data visualized in the program PowerGraph 3.3. But I had to change the algorithm of the system for the following reasons: (1) neurointerface is in testing and tuning stage (this is another project). The project was able to use only one of the four channels removal of electrical signals. Instead BT channel used for transmission of USB data channel. (2) Intel Galileo board contains no built-BT and WiFi devices. Experience team and a limited time frame of the project is not allowed to connect to the motherboard external device BT and WiFi. As a result, a temporary solution was implemented: (1) The electric signal is taken from a human body part with a single active electrode in analog form and transmitted to the mobile neyrointerfeys input. (2) Mobile neyrointerfeys amplifies an analog signal from one channel, digitizes it, and transmits a USB channel Intel Galileo charge. (3) Intel Galileo performs digital signal processing (signal filtering and recovering the alpha and beta rhythms), and transmits the results of processing (rhythm) in a laptop USB channel. (4) On the laptop data visualized in the program PowerGraph 3.3. General view of the bio signal acquisition and processing system of the prototype is shown below. Prototype program calculate alpha and beta rhythms can be found here. (We used the FFT library, designed by Tom Roberts.) Work on the development of the project continues.