Hardware

BrainAccess hardware is exclusively based on dry-contact electrodes.

The electrodes have been developed to be optimal in terms of size, signal quality and comfort. They feature 12 gold-plated spikes, each spike is spring-loaded allowing for the electrode to conform to the curvature of the head, therefore, increasing the comfort when compared to standard dry-contact electrodes. The back of the electrode is shielded to ensure maximum isolation from external noise sources. For EEG measurements where there is no hair, gold-plated pad electrodes are used instead of spike electrodes for improved contact and comfort.

BrainAccess electroencephalographs are wireless, lightweight, battery-powered devices in order to make them truly portable devices that can be used in different environments. They feature multi-channel EEG inputs with a common reference channel and also additional data inputs such as the accelerometer. They offer active noise suppression and come with shielded mini cables to minimize the effects of the surrounding environment. Multiple electroencephalographs can be connected to the same computer for multi-user experiments and applications. Multiple electroencephalographs can be synchronized in time-sensitive applications.

BrainAccess headwear offers usage flexibility, BrainAccess CAP is available in different sizes and with a different number of electrodes. The CAP follows the standard 10-20 system with a large number of available mounting positions for electrodes.

BrainAccess MINI

The BrainAccess MINI is a 8-channel electroencephalograph with a common reference channel.

Its compact size, Bluetooth connectivity and long battery life make it a truly portable device.

Overview

USB Bluetooth adapter

The device comes with a USB Bluetooth 4.2 adapter, which is used to communicate and stream data to the computer from BrainAccess MINI. If preferred, a different Bluetooth adapter such as an integrated Bluetooth adapter in a laptop may be used instead.

Power switch

Press and hold a push-button for a couple of seconds to turn the device on/off. Power LED will be lit when powered on.

Charging port

The device's battery can be charged via a micro-USB port using standard 5V chargers such as mobile phone chargers with a micro-USB plug. The charger should be capable of providing at least 800 mA of current. Do not use the device when charging with chargers powered from grid electricity due to safety reasons and potentially 50/60 Hz noise affecting the signals. The device can be used when charging from a power bank though.

Power LED

It is a red-colored LED that indicates when the device is powered on. If the power LED starts blinking, it indicates that the battery level is below <10% and needs charging soon.

Connection LED

It is a blue-colored LED that indicates when a Bluetooth connection is established between a computer and the device.

EEG inputs

These inputs should be connected to electrodes that measure EEG activity with respect to the reference electrode.

Reference input

An input that should be connected to a common reference electrode. In BrainAccess Kit setups it is typically an electrode placed at the Fp1 location. The connection is denoted as 'R' on the device.

Bias input

An input that should be connected to a bias electrode. In BrainAccess Kit setups it is typically an electrode placed at the Fp1 location. The connection is denoted as 'B' on the device. It is a driven bias that which reduces the common mode noise such as noise coming from the grid electricity. The bias signal is derived from any of the EEG inputs which can be chosen in software. They are denoted as `bias feedback channels' in software. Use only channels/electrodes that have good quality signals for bias feedback.

Digital input

The device has an additional digital input that is sampled at the same rate as EEG signals and is treated as an additional input channel in software. It can be used for connecting external sensors or for synchronizing multiple BrainAccess MINI devices. The digital input is internally pulled high and is driven low when input contacts are closed. An external switch or open-collector/open-drain circuits can be used to close the digital input contacts and drive the digital signal low.

Accelerometer

The device has an integrated 3-axis accelerometer. It can be used for example to record any body/head movements when it is attached to the EEG cap. The accelerometer data comes as 3 additional input channels in the software.

Velcro tape attachment

A velcro tape can be found at the bottom of the device that can be used to attach it to the BrainAccess CAP.

Specifications

Specifications of BrainAccess MINI electroencephalograph.

Connectivity
Type	Bluetooth 4.2
Range	up to 10m (using the provided Bluetooth adapter)
EEG Input Channels
Number of channels	8 + common reference channel
Sampling frequency	250 Hz
Input resolution	24 bits
Analog gain values	1, 2, 4, 6, 12, 24
Input voltage range	4500 mV / gain value (w.r.t. reference channel)
Input connector	Ultra-mini RF coaxial connector
Digital Input Channel
Type	internally pulled-up, driven low by closing the input contacts
Sampling frequency	250Hz
Connector	JST right-angle, 2 mm pitch, cable with a plug also provided
Accelerometer
Number of axis	3
Sampling frequency	50Hz (resampled to 250Hz in software)
Range	+/-2g
Resolution	10 bits
Battery
Type	Li-Po
Capacity	1500 mAh
Operating time	up to 6 hours (continuous streaming, all channels turned on)
Charging time	2 hours
Charger input	5V 800 mA min (charger not included)
Charger connector	micro-usb
Mechanical
Mass	70g
Dimensions	68x50x21 mm

BrainAccess MIDI

BrainAccess MIDI is a 16 channel electroencephalograph with a common reference channel. It is more powerful than MINI with extra EEG channels and longer battery life.

Overview

USB Bluetooth adapter

The device comes with a USB Bluetooth 4.2 adapter, which is used to communicate and stream data to computer from BrainAccess MIDI. If preferred, a different Bluetooth adapter such as an integrated Bluetooth adapter in a laptop may be used instead.

Power switch

Press and hold a push button for a couple of seconds to turn the device on/off. Power LED will be lit when powered on.

Charging port

The device's battery can be charged via micro-USB port using standard 5V chargers such as mobile phone chargers with micro-USB plug. The charger should be capable of providing at least 800 mA of current. Do not use the device when charging with chargers powered from grid electricity due to safety reasons and potentially 50/60 Hz noise affecting the signals. The device can be used when charging from a power bank though.

Power LED

It is a red-coloured LED that indicates when the device is powered on. If the power LED starts blinking, it indicates that the battery level is below <10\% and needs charging soon.

Connection LED

It is a blue-coloured LED that indicates when a Bluetooth connection is established between a computer and the device.

EEG inputs

These inputs should be connected to electrodes that measure EEG activity with respect to the reference electrode.

Input connector-converter

An input connector-converter has input connections for all the cables coming from each electrode on one end and a single socket connection to the MIDI on the other end. This allows, for example, disconnecting MIDI quickly from an EEG cap and connecting to another EEG cap with a different setup.

Reference input

An input that should be connected to a common reference electrode. In BrainAccess Kit setups it is typically an electrode placed at Fp1 location. The connection is denoted as 'R' on the device.

Bias input

An input that should be connected to a bias electrode. In BrainAccess Kit setups it is typically an electrode placed at Fp2 location. The connection is denoted as 'B' on the device. It is a driven bias which reduces the common mode noise such as noise coming from the grid electricity. The bias signal is derived from any of the EEG inputs which can be chosen in software. They are denoted as `bias feedback channels' in software. Use only channels/electrodes that have good quality signals for bias feedback.

Digital input

The device has an additional digital input that is sampled at the same rate as EEG signals and is treated as an additional input channel in software. It can be used for connecting external sensors or for synchronizing multiple BrainAccess MIDI devices. The digital input is internally-pulled high and is driven low when input contacts are closed. An external switch or open-collector/open-drain circuits can be used to close the digital input contacts and drive the digital signal low.

Accelerometer

Velcro tape attachment

A velcro tape can be found at the bottom of the device that can be used to attach it to the BrainAccess CAP.

Specifications

Specifications of BrainAccess MIDI electroencephalograph.

Connectivity
Type	Bluetooth 4.2
Range	up to 10m (using the provided Bluetooth adapter)
EEG Input Channels
Number of channels	16 + common reference channel
Sampling frequency	250 Hz
Input resolution	24 bits
Analog gain values	1, 2, 4, 6, 12, 24
Input voltage range	4500 mV / gain value (w.r.t. reference channel)
Input connector	Ultra-mini RF coaxial connector
Digital Input Channel
Type	internally pulled-up, driven low by closing the input contacts
Sampling frequency	250Hz
Connector	JST right-angle, 2 mm pitch, cable with a plug also provided
Accelerometer
Number of axis	3
Sampling frequency	50Hz (resampled to 250Hz in software)
Range	+/-2g
Resolution	10 bits
Battery
Type	Li-Po
Capacity	2200 mAh
Operating time	up to 9 hours (continuous streaming, all channels turned on)
Charging time	3 hours
Charger input	5V 800 mA min (charger not included)
Charger connector	micro-usb
Mechanical
Mass	85g
Dimensions	92x50x23 mm

BrainAccess CAP

The BrainAccess CAP is a versatile EEG cap that is available in different sizes and comes with dry-contact, shape-conforming gold electrodes.

The BrainAccess CAP is designed to work with BrainAccess electroencephalographs and can be purchased as part of BrainAccess kits.

3 different sizes. The cap is available in 3 different sizes: L, M, S to fit different adult head sizes and shapes.

Overview

Number of electrodes

The total number of the electrodes provided with the cap varies depending on the purchased kit, the BrainAccess Standard Kit has 8 spike electrodes and 2 pad electrodes.

Dry-contact electrodes

The cap comes with dry-contact electrodes. The electrodes feature spring-loaded spikes that enable the electrode to conform to the curvature of the head resulting in more comfortable wear when compared to standard dry-contact electrodes.

Dry-contact pad electrodes

Electrodes with golden pads are provided for the positions without hair, i.e. forehead.

37 electrode positions

The cap provides 37 positions where the electrodes can be placed using an easy-to-use clipping mechanism. The positions follow the standard 10-20 system.

Easy electrode placement

It is easy to change the positions of the electrodes on the cap using the standard clipping mechanism.

Holes for cables

Additional holes are provided for the cables to ensure the tidiness of the setup.

Ultra small cables

The CAP is equipped with ultra-miniature coaxial cables that not only ensure shielding from the noise but are also thin and flexible to ensure comfort. The cables can be directly plugged into the BrainAccess electroencephalographs.

Machine washable

For hygienic purposes, the cap can be machine washed using a delicate wash cycle. Make sure to remove the electrodes and cables from the cap before washing. The electrodes can be cleaned with standard disinfectant liquids/sprays and non-abrasive wipes.

Velcro tape attachment

The cap features a piece of velcro tape on the backside of the cap. BrainAccess electroencephalograph should be attached there.

Specifications

Specifications of BrainAccess CAP.

Size	L (54-59 cm)
	M (50-55 cm)
	S (48-52 cm)
Colour	black
Number of holes for electrode attachments	37
Number of holes for cables	18
Electrodes
Type	dry-contact
Material	gold-plated
Diameter	19.5 mm
Number of spikes	12 x spring-loaded
Number of pads (forehead)	5 x 6mm diameter
Input connector	ultra-mini RF coaxial connector
Cables
Type	Ultra miniature RF coaxial
Length	different lengths provided for different positions

Hardware

Hardware

BrainAccess hardware is exclusively based on dry-contact electrodes.

BrainAccess MINI​

Overview

USB Bluetooth adapter

Power switch

Charging port

Power LED

Connection LED

EEG inputs

Reference input

Bias input

Digital input

Accelerometer

Velcro tape attachment

Specifications

BrainAccess MIDI

Overview

USB Bluetooth adapter

Power switch

Charging port

Power LED

Connection LED

EEG inputs

Input connector-converter

Reference input

Bias input

Digital input

Accelerometer

Velcro tape attachment

Specifications

BrainAccess CAP

Overview

Number of electrodes

Dry-contact electrodes

Dry-contact pad electrodes

37 electrode positions

Easy electrode placement

Holes for cables

Ultra small cables

Machine washable

Velcro tape attachment

Specifications

Table of Contents

BrainAccess MINI