title: A low-cost, portable, micro-controlled device for multi-channel LED visual stimulation.
abstract: Light emitting diodes (LEDs) are extensively used as light sources to investigate visual and visually related function and dysfunction. Here, we describe the design of a compact, low-cost, stand-alone LED-based system that enables the configuration, storage and presentation of elaborate visual stimulation paradigms. The core functionality of this system is provided by a microcontroller whose ultra-low power consumption makes it well suited for long lasting battery applications. The effective use of hardware resources is managed by multi-layered architecture software that provides an intuitive and user-friendly interface. In the configuration mode, different stimulation sequences can be created and memorized for ten channels, independently. LED-driving current output can be set either as continuous or pulse modulated, up to 500 Hz, by duty cycle adjustments. In run mode, multiple-channel stimulus sequences are automatically applied according to the pre-programmed protocol. Steady state visual evoked potentials were successfully recorded in five subjects with no visible electromagnetic interferences from the stimulator, demonstrating the efficacy of combining our prototyped equipment with electrophysiological techniques. Finally, we discuss a number of possible improvements for future development of our project.
authors.affiliation: Department of Electrical Engineering, School of Engineering, Laboratory of Biomedical Engineering, Universidade Federal de Minas Gerais, Av. Antônio Carlos 6627, 31270-010 Belo Horizonte, MG, Brazil.
authors.forename: Marcos Antonio da Silva
authors.initials: MA
authors.lastname: Pinto
authors.forename: John Kennedy Schettino
authors.initials: JK
authors.lastname: de Souza
authors.forename: Jerome
authors.initials: J
authors.lastname: Baron
authors.forename: Carlos Julio
authors.initials: CJ
authors.lastname: Tierra-Criollo
mesh_terms: D000328:Adult; D003201:Computers / Q000592:standards; D004569:Electroencephalography / Q000379:methods*; D004582:Electronics, Medical / Q000191:economics / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design / Q000295:instrumentation* / Q000379:methods; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D055617:Micro-Electrical-Mechanical Systems / Q000295:instrumentation / Q000379:methods; D008875:Middle Aged; D010775:Photic Stimulation / Q000295:instrumentation* / Q000379:methods; D012984:Software / Q000592:standards; D055815:Young Adult