A brain-computer interface (BCI) serves as a direct communication link between the brain and external devices, categorized into invasive, partially invasive, and non-invasive types. Special techniques such as EEG, ECoG, and fMRI are employed for signal acquisition, each varying in invasiveness and accuracy. Despite its potential to assist individuals with disabilities, BCI faces challenges such as weak signals, interference, and risks associated with surgical procedures.

1. BRAIN-COMPUTER INTERFACE The next generation user interface

2. INTRODUCTION A Brain-Computer Interface (BCI) is a direct communication pathway between the human or an animal brain and an external device

3. CLASSIFICATION BCI INVASIVE BCI PARTIALLY INVASIVE BCI NON-INVASIVE BCI

4. INVASIVE BCIs Electrodes are implanted directly into the grey matter of the brain Produces High quality of signals Prone to scar tissue build up Causes the signal to become weaker or even lost

5. PARTIALLY INVASIVE BCIs BCIs are implanted inside the skull Electrodes are placed on the surface of cortex The electrode picks up neural firing from the surface of the brain

6. Non- invasive BCIs BCIs have electrodes carefully placed on a cap that the patient wears Has no complications of brain surgery Signals are very noisy and are often misunderstood by the computer

7. Block diagram for BCI devices

8. Signal Acquisition Different ways of extracting signals form the brain Direct neural contact ECoG fMRI EEG

9. DIRECT NEURAL CONTACT Most accurate method Highly Invasive Electrode picks up highly clear signals Signals get weaker if scar tissue develops

10. Electrocorticography(EcOG) Partially Invasive Consists 16 sterile, stainless steel, carbon tip, gold ball electrodes ECoG is mainly used to detect the Visual and Auditory stimuli

11. FUNCTIONAL Magnetic Resonance Imaging (fMRI) Type of specialized MRI scans Measures blood flow in brain using MRI Studies the brain‘s function Very Accurate High cost due to MRI

12. ELECTROENCEPHALOGRAPHY(eeG) Electronic monitoring device to measures electrical activity in brain Pain less test Used to record the electrical signals from the brain Used to confirm brain death

13. electroencephalogram

14. Interface via eeg VEP (Visual Evoked Potential) P300 (Potential 300) SSVEP (Steady State Visual Evoked Potential)

15. Visual evoked potential Caused by sensory stimulation of subjects visual fields VEP is observed using EEG VEPs are very useful in detecting blindness Flashing lights, checker boards that flickers are commonly used visual stimuli

16. P 300 Unexpected sensory stimuli Peeks in the vicinity of 300 ms and lie for very simple decisions Longer it takes for P 300 to appear in harder decision Used for screening terrorists and other criminals

17. SSVEP Steady State Visual Evoked Potential SSVEP are signals that are natural responses to visual stimulation This technique is used widely used in Electroencephalographic research regarding vision

18. Pros & cons Can help people with inabilities to control wheel chairs or other devices with brain activity To develop better sensing system BCIs are linguistic independent and can be used any where across the world The signals are weak and are prone to interference Surgery to brain might be risky and cause brain death There are chemical reactions involved in brain which BCI devices cannot pick up

19. CONCLUSION BCI research is an interdisciplinary endeavor involving neuroscience , engineering , signal processing, and clinical rehabilitation , and lies at the intersection of several emerging technologies such as Machine Learning and Artificial Intelligence among others. BCI is considered as an new frontier in science and technology

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