EEG is a medical device for analysing the electrical activity of the brain.

It can detect Epilepsy or Alzheirmer’s diseases.

It was used in humans by Hans Berger in 1924.

The general mechanism is picking up the charge of electrical potentials. 

They pick up the brain’s electrical signals and send them to a machine called Electroencephalogram


EEG machine is used for a medical test to measure the electrical activity of the brain, via electrodes applied to the scalp or through microelectrodes placed within the brain tissue.

Electrodes are attached to multiple sites on the scalp to provide a recording of electrical activity that is generated in the cerebral cortex.


Electrical impulses are transmitted to an electroencephalograph, which magnifies and records these impulses as brawe on a strip of paper.


Experiments have shown that the frequency of the EEG seems to be affected by the mental activity of a person. The frequencies of the brain wave range from 0.5 to 1000Hz, and their character is highly dependent on the degree of activity of the cerebral cortex. Some of these are characteristics of specific abnormalities of the brain, such as epilepsy.


Where there is a need to diagnose and manage epilepsy. It is used to investigate other conditions such as head injuries, brain tumors, dementia, hemorrhage. It determines the level of brain function in people who are in a coma. It identifies areas of the brain that are not working properly.


Routine EEG test- EEG test done at an outpatient appointment at the hospital (lasts about one hours).

Ambulatory EEG test- it records the activity in the brain over a few hours, days or weeks, allowing more time for the test to pick up any unusual electrical activity in the brain, the electrodes are plugged into a small monitor that records the result.

Sleep EEG test- an EEG test is done while the patient is asleep, usually done in hospital, using a routine EEG machine. Before the test, the patient may be given some medicine to include sleep. The test lasts one to two hours or up to 8 hours and the patient goes home onces he goes up.

Video elementary test- A patient wears an ambulatory EEG usually carried out over a few days. All movements are recorded by a video camera. The patient needs to stay in the hospital.


When the EEG is finished, the results are interpreted by a neurologist, the EEG records the brain wave from various locations in the brain. Each area produced a different brain wave strip for the neurologist to interpret.

There are two types of EEG test result

Normal results- Brain electrical activity has certain frequencies ( the number of waves per second) that are normal for different levels of consciousness. For example, brain waves are faster when the person is awake, and slower when he/she is sleeping. There are also normal patterns to these waves.

Abnormal results- abnormal results on an EEG test may be due to:

  • An abnormal structure in the brain(such as a brain tumor)
  • Attention problems
  • Tissue death due to a blockage in blood flow ( cerebral infarction)
  • Drag or alcohol abuse
  • Head injury
  • Inflammation of brain 
  • Hemorrhage
  • Migraines
  • Seizure disorder
  • Sleep disorder



A standard noninvasive EEG takes about 1 hours. The patient will be positioned on a padded bed or table. 

To measure the electrical activity in various parts of the brain, a nurse or EEG technician will attach 16 to 20 electrodes on the scalp.

The brain generates electrical impulses that these electrodes will pick up.

To improve the induction of these impulses to the electrodes, a gel will be applied to them.

The electrodes only gather the impulses given off by the brain and do not transmit any stimulus to the brain. 

The technician may tell the patients to breathe slowly and quickly or may use visual stimuli such as flashing light to see what happens in the brain when the patients see these things.

The brain’s activity is recorded continuously throughout the exam on special EEG paper.


After the test is completed, the technician will remove the electrodes.

The patient will be instructed when to resume any medications.

The patient should avoid activities that may harm them if a seizure occurs, until they have resumed their seizure medication for an adequate length of time.

These medications do not necessarily apply to the person who was not on seizure medication prior to the EEG.

The doctor will tell the patient when and how they will learn the result of their EEG.



  • Hardware costs are significantly lower than those of most other techniques.
  • EEG has very high temporal resolution, on the order of milliseconds rather than second.
  • Extremely non-invasive
  • EEG is silent, which allow for better study of the responses to auditory stimuli
  • EEG does not involve exposure to high-intensity magnetic fields


  • It is not very exact. It can only measure activity on general areas, not specific neural connections.
  • May experience discomfort from sticky paste and electrodes.
  • Too much noise in system
  • It’s recording is poor 
  • Two channel insufficient for measurement
  • Possible to build more channel
  • Filter drop off too shallowly to isolate bands


Neurofax µ EEG-9100

Nihon Kohden
Neurofax µ EEG-9100

  • Portable and lightweight — you can easily carry a complete system in a car or airplane
  • Clean signal acquisition in any environment
  • Multi-function electrode junction box (JE-921A)25 EEG, 14 bipolar (7 pairs), 4 DC, SpO2, CO2 connectors
  • Economical — use the same junction box for routine EEG and PSG
  • USB connection


  • 8 channel DSA trendgraph
  • 64 channels plus 1 event marker channel display
  • Standard Windows® networking
  • Digital video option
  • Automatic photic stimulation


  • Too much noise in system
  • It’s recording is poor 
  • Two channel insufficient for measurement
EEG machine allengers

(EEG Machine)

  • 40 Channel EEG.
  • Multiple sampling rates – 256, 512, 1024 Hz.
  • Power spectra and coherence.
  • Irregular heart Beat analysis software.
  • Bedside impedance with glowing LED on headbox.
  • Features like Amplitude Integrated EEG (AEEG), CSA/DSA frequency distribution, brain mapping, etc.
  • Facility to send EEG data through e-mail.


  • Faulty electrode tester on headbox.
  • Printouts on A3 papers.
  • Video recording of 2 camera’s simultaneously (optional).
  • Flexible photic stimulator based on high-intensity LED’s.


  • The EEG signal is not useful for pin-pointing the exact source of activity. In other words they are not very exact.
  • the waveform does not researchers to distinguish between activities originating in different but closely adjacent locations.
EEG machine vigro

(EEG Machine)

  • 24 / 32 / 40 Channel EEG.
  • Plug & play USB with portable EEG (no need of external supply).
  • Lightweight & compact amplifier with high quality of electrodes.
  • Features like Amplitude Integrated EEG (AEEG), CSA/DSA frequency distribution, brain mapping, etc.
  • User editable unlimited numbers of montages.


  • Optional: Synchronized high-resolution MPEG-4 video with EEG recording.
  • Optional: SPO2, HR & pleth recording facility.
  • Optional: Battery, high end camera (pan, tilt & zoom).


  • it can directly display areas of the brain that are active, while EEG requires intense interpretation just to hypothesize what areas are activated by a particular response.
  • EEG poorly measures neural activity that occurs below the upper layers of the brain (the cortex).
EEG machine neurocare


  •  It support optional photic stimulator with event stimulation to evoke patient’s epilepsy seizure.
  • it can work with optional infra-red video system to support night monitoring for patients in hospital.
  • specification input channels: 2040 ch eeg;13ch psg power supply: 4 6v aa battery, rechargeable battery or external rechargeable lithium battery; internal memory: sd card (2g); 21 hours for 23 channels with 4 aa battery 


  • 18 hours recording for 33 channels with 4 aa battery ( 54 hours with external lithium battery )
  • 15 hours for 53 channels with 4 aa battery ( 45 hours with external lithium battery )
  • connection to pc: wireless bluetooth for real-time data transmission;
  • usb(2.0) for data uploading from sd card
  • operation modes: real-time
  • ltm ( long term monitoring )


  • Often takes a long time to connect a subject to EEG, as it requires precise placement of dozens of electrodes around the head and the use of various gels, saline solutions, and/or pastes to maintain good conductivity, and a cap is used to keep them in place. 
EEG machine natus


  • The Natus NeuroWorks platform simplifies the process of collecting, monitoring and managing data for routine EEG testing, ambulatory EEG, long-term monitoring, ICU monitoring, and research studies. NeuroWorks systems are scalable to meet the needs of private practice clinics, hospitals and large teaching facilities. Natus NeuroWorks is a cutting-edge, single solution for EEG, LTM, ICU, Sleep, and Research Studies, exhibiting an advanced software for clinical excellence.


  •  Filter studies by date, status, diagnosis, or use any built-in editable field to create custom filters for your unique needs.
  • Track outcomes and filter by statistical indices that are calculated in the reports.
  • The distributed database automatically updates system settings across the network to ensure that all workstations have current lab settings.


  • While the length of time differs dependent on the specific EEG device used, as a general rule it takes considerably less time to prepare a subject for MEG, fMRI, MRS, and SPECT.
  • Signal-to-noise ratio is poor, so sophisticated data analysis and relatively large numbers of subjects are needed to extract useful information from EEG


1.Medicaid Wireless EEG Machine – Necton-WF Series1,54,000
2.Allengers Neuroplot EEG Machine1,30,000
3.Allengers VIRGO EEG Machine1,35,000
4.RMS Brain View Plus 24 Channel EEG Machine1,38,000
5.Medicaid Ultra Portable Pocket EEG Machine 1,54,000
6.Medicaid NC Series Neuro Compact Portable EEG Machine1,20,000
7.RMS Maximus Portable EEG Machine 32 channel1,51,200
8.RMS Super Spec 32 Channel EEG Machine 1,40,000
9.RMS Maximus Portable EEG Machine 24 channel1,23,200
10.Clarity Brain Tech 40+ EEG Machine1,60,000




Although the diagnoses od disease through EEG may seem simple to the reader, but it is not as simple as it seems, because in many disease such as seizure, it does not cause a typical pattern on EEG, it just cause a case in the EEG. this means the some time the EE is described as ‘abnormal’ but does not specify the abnormalities. in general EEG is the best method to diagnoses and it is better than it’s alternatives for many reasons, and there are almost no low-cost alternative of EEG


How reliable is an EEG?

EEG review yielded 1-week accuracy in 10–52% of recordings, and 2-week accuracy in 28–75% of recordings (n = 146; Fig. 3E and F).

What is the normal result of EEG?

Most waves of 8 Hz and higher frequencies are normal findings in the EEG of an awake adult. Waves with a frequency of 7 Hz or less often are classified as abnormal in awake adults, although they normally can be seen in children or in adults who are asleep.

How to read EEG signal?

EMG or Muscle wave: generally from 80~3000Hz with most energy at 100Hz or above.
Super beta (β) or gamma (γ) wave: from 30~150Hz with most energy between 60~100Hz, associated with visual processing, problem solving and memory work.

What is amplitude in EEG?

Amplitude, EEG: Is a measure of the change of EEG signals with respect to the mean value, usually measured in microvolts (µV), and often expressed as the difference between the maximum and minimum deviation (i.e. peak-to-peak), or in rectified EEG from baseline-to-peak.

What are Brainwaves?

Delta waves (. 5 to 3 Hz)
Theta waves (3 to 8 Hz) Theta brainwaves occur most often in sleep but are also dominant in deep meditation.
Alpha waves (8 to 12 Hz)
Beta waves (12 to 38 Hz)
Gamma waves (38 to 42 Hz)

What does low amplitude in EEG mean?

An EEG with a large amplitude and a low frequency indicates a more synchronized brain wave pattern (groups of cells are acting in concert), whereas an EEG with a low amplitude and a high frequency generally corresponds with a desynchronized brain wave pattern (groups of cells are involved in separate activities).