title: A novel and inexpensive digital system for eye movement recordings using magnetic scleral search coils.
abstract: After their introduction by Robinson (IEEE Trans Biomed Eng 10:137-145, 1963), magnetic scleral search coils quickly became an accepted standard for precise eye movement recordings. While other techniques such as video-oculography or electro-oculography may be more suitable for routine applications, search coils still provide the best low-noise and low-drift characteristics paired with the highest temporal and spatial resolution. The problem with search coils is that many research laboratories still have their large and expensive coil systems installed and are acquiring eye movement data with old, analog technology. Typically, the number of recording channels is limited and modifications to an existing search coil system can be difficult. We propose a system that allows to retro-fit an existing analog search coil system to become a digital recording system. The system includes digital data acquisition boards and a reference coil as the hardware part, receiver software, and a new calibration method. The circuit design has been kept simple and robust, and the proposed software calibration allows the calibration of a single coil within a few seconds.
authors.affiliation: Psychological and Brain Sciences Department, Active Perception Laboratory, Boston University, Boston, MA, 02215, USA. karin.eibenberger@gmail.com.|Department of Mechanical Engineering, Technical University of Vienna, 1040, Vienna, Austria. karin.eibenberger@gmail.com.|Department of Otolaryngology and Head- and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, 21287, USA. karin.eibenberger@gmail.com.|Department of Medical Engineering, University of Applied Sciences Upper Austria, 4020, Linz, Austria. karin.eibenberger@gmail.com.
authors.forename: Karin
authors.initials: K
authors.lastname: Eibenberger
authors.affiliation: Department of Otolaryngology and Head- and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, 21287, USA.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Eibenberger
authors.affiliation: Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, 21287, USA.
authors.forename: Dale C
authors.initials: DC
authors.lastname: Roberts
authors.affiliation: Department of Medical Engineering, University of Applied Sciences Upper Austria, 4020, Linz, Austria.
authors.forename: Thomas
authors.initials: T
authors.lastname: Haslwanter
authors.affiliation: Department of Otolaryngology and Head- and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, 21287, USA.
authors.forename: John P
authors.initials: JP
authors.lastname: Carey
mesh_terms: D000328:Adult; D005133:Eye Movements / Q000502:physiology*; D006801:Humans; D060328:Magnetic Phenomena; D012815:Signal Processing, Computer-Assisted; D014741:Video Recording / Q000191:economics* / Q000295:instrumentation*
keywords: Biomedical electronics; Biomedical signal processing; Eye movement; Head impulse test; Search coil