Transcranial direct current stimulation
Transcranial direct current stimulation delivers constant low current to the brain area of interest via electrodes on the scalp. StarStim (Neuroelectrics, Barcelona, Spain) is a wireless hybrid EEG/tDCS 8-channel neurostimulator that includes a comfortable neoprene headcap with 39 positions based on the 10-10 system where the electrodes can be easily inserted.
A 4-wall 3D CAVE system (Barco N.V., Kortrijk, Belgium) allows user immersion in stereoscopic scenarios with a 7.1 sound system or with Bluetooth headphones. The system uses 4 projectors F35 AS3D WUXGA (ProjectionDesign, Fredrikstad, Norway) and incorporates head and hands tracking through 4 infrared tracking cameras ARTTRACK2 (Advanced Realtime Tracking GmbH, Weilheim in Oberbayern, Germany) and navigation through Flystick3 (Advanced Realtime Tracking GmbH, Weilheim in Oberbayern, Germany).
A setup that consists of two video projectors Mirage HD3 projector (Christie Digital Systems USA Inc, Cypress, CA, USA) provides a stereoscopic 6 x 2 meter display that also allows head and hands tracking through other 4 infrared tracking cameras ARTTRACK2 and navigation through Flystick3.
Walking room-size virtual reality system
An optical-based system that consists of a head mounted display, a Bluetooth headset and a videocamera allows navigation in virtual and mixed reality environments by walking in an area of 4 x 6 meter.
Head mounted displays
Different head mounted displays are available for augmented, mixed, and virtual reality applications. Available devices for virtual reality applications include the Oculus Rift DK1, the Oculus Rift DK2 (Oculus VR, Irvine, CA, USA), and the Samsung Gear VR (Samsung, Suwon, South Korea). Optical see-through devices available for augmented reality applications are the Meta1 (Meta Company, Portola Valley, CA), which incorporates a 3D time-of-flight depth camera with 320×240 pixel resolution, the Moverio BT-200 (Epson, Suwa, Japan), the Google Glass (Google, Menlo Park, CA, USA), and the Vuzix M200 (Vuzix, Rochester, NY, USA).
Scent emitting system
The Scent Palette (HeadHunter200 Inc., Northlake, IL, USA) can emit a selected scent and produce a sequence of different smells controlled by a computer. The stimulation can also be provided additionally to other sensory stimulation in virtual reality settings.
TV screens and projectors
Different additional TV and projectors with different features are available to customize the required setup for each experiment.
Monitoring, behavior tracking, and capture
Electroencephalography records the electrical activity of the brain through electrodes that are fixed to the scalp. Different solutions can be used depending on the experimental conditions. The TMSi Refa (Twente Medical Systems International B.V., Oldenzaal, Netherlands) is a 32-channel ambulatory and stationary system for physiological research that allows to retrieve data from water based sensors. For mobile applications, the StarStim allows to retrieve data from 8 channels wirelessly in hybrid configurations of transcraneal direct current stimulation, and the B-Alert X10 (Advanced Brain Monitoring, Inc., Carlsbad, CA, USA) provides 9 channels of combined mid-line and lateral EEG sites plus an additional channel of electrocardiography, electromyography, or electroculography. In addition, four EPOC headsets (Emotiv Systems, Kwun Tong, Hong Kong).
Eye tracking technology estimates where individuals direct their eyes along time. These data can provide information about attention, information processing, presence, focus, drowsiness, consciousness, or other mental states. Eye tracking information can be retrieved using different devices. The Tobii TX300 (Tobii Technology AB, Danderyd, Sweden) collects gaze data at 300 Hz yet allows large head movements, thus enabling the study of saccades, correction saccades, fixations, pupil size changes, and blinks. Other portable solutions are also available for different setups, as the low-cost Tobii EyeX (Tobii Technology AB, Danderyd, Sweden) and the Eye Tribe (Copenhagen, Sweden) or the high performance SMI Eye Tracking Glasses 2 (SensoMotoric Instruments GmbH, Teltow, Germany). This device not only allows to record a person’s natural gaze behaviour in real-time in a broad range of daily life applications but also in our CAVE system, for which the Arrington Scene Camera Eye Tracking (Arrington Research Inc, Scottsdale, AZ, USA).
The TMSi Refa can provide surface electromyography data, a non-invasive technique that estimates the electrical activity of a muscle placing electrodes on (not into) the skin overlying it.
Galvanic skin response
Galvanic skin response or skin conductance represents the changes in the electrical properties of the skin, which can illustrate the autonomic nerve responses as a parameter of the sweat gland function. This physiological measure can be estimated using the TMSi Refa , which uses two electrodes that are attached to a finger, the Q-sensor (Affectiva, Waltham, MA, USA), a wireless Bluetooth bracelet, or the E4 wristband (Empatica, Milan, Italy).
The electro-physiological measurement of the heart muscle signal or electrocardiography can be obtained using the TMSi Refa. Besides the heart rate variability, the system also allows to extract the size and position of the chambers and the presence and place of any damage to the heart. Measures of the blood volume pulse, from which heart rate, heart rate variability, and other cardiovascular features may be derived can be estimated using the photoplethysmography sensor of the E4 wristband.
The skin temperature can be measured via a thermic sensor using the TMSi Refa or via infrared thermopile using the E4 wristband.
The fraction of oxygen-saturated hemoglobin relative to total hemoglobin in the blood can be provided by the TMSi Refa.
Human movements can be detected by many different devices. The IGS150 (Synertial, Brighton, United Kingdom) is a motion capture solution that estimates de orientation of 15 inertial sensors made up of 9 axes of accelerometers, magnetometers and gyroscopes combined together. Two IGS-Cobra gloves with 7 sensors are also available for hand tracking capture. Conventional tracking systems detect the position of markers, as the optical solution using OptiTrack V100:R2 cameras (NaturalPoint, Corvallis, OR, USA), or sensors, as the electromagnetic G4 (Polhemus, Colchester, VT, USA), which are usually attached to specific body parts to determine their position in a 3D environment. Recent advances in computer vision have made human pose recognition from depth images reality. Even though it cannot be considered as a tracking system in the literal sense, the skeleton tracking provides the 3D position of many body joints from depth information estimated by depth sensors, such as the Kinect and Kinect v2 (Microsoft, Redmond, WA, USA), the Intel RealSense F200 (Creative Technology Ltd, Singapore), and the Structure Sensor (Occipital Inc, Boulder, CO, USA).
Other devices for natural interaction are also available. The Leap Motion (Leap Motion Inc, San Francisco, CA, USA) allows user to interact with finger and hand movements. The Razer Hydra (Razer, Irvine, CA, USA) estimates arm movements by using a weak magnetic field to detect the absolute position and orientation of the controllers with high precision. In contrast to these devices, the Myo armband (Thalmic Labs, Kitchener, ON, Canada) allows users to interact with gestures by detecting the surface electrical activity of the wrist muscles.
Full 360º video recordings can be obtained combining 14 GoPro Hero 3 (360Heros, Olean, NY, USA). Natural audio can be captured using the binaural audio microphone 3Dio Free Space (J.Tesori Co, Tokyo, Japan) and the Zoom H4n handy recorder (Zoom Corporation, Tokyo, Japan).
I3B improved its facilities in 2018 with 3D motion tracking system for four simultaneous users. All these equipment has been funded by the European Union within the Program ERDF operation of the Valencian Community 2014-2020 with the grant number IDIFEDER/2018/029. These grants were published in the DOGV number 8263 in 2018, Mar, 28th.
LabLENI has received a grant from the GVA for the acquisition of a highly immersive, multi-user system with body movement tracking and social signal processing capacity using artificial intelligence techniques. These equipment has been funded by the European Union within the Program ERDF operation of the Generalitat Valenciana 2021-2022 with the grant number IDIFEDER/2021/038 regarding infrastructure and equipment for R+D+r.