Note that this reference documentation is identical to the help that is displayed in MATLAB when you type “help ft_read_sens”.

  FT_READ_SENS read sensor positions from various manufacturer specific files. The
  following acquisition system and analysis platform file formats are currently
    asa_elc besa_elp besa_pos besa_sfp yokogawa_ave yokogawa_con yokogawa_raw 4d
    4d_pdf 4d_m4d 4d_xyz ctf_ds ctf_res4 itab_raw itab_mhd netmeg neuromag_fif
    neuromag_mne neuromag_mne_elec neuromag_mne_grad polhemus_fil polhemus_pos
    zebris_sfp spmeeg_mat eeglab_set localite_pos matlab
  Use as
    grad = ft_read_sens(filename, ...)  % for gradiometers
    elec = ft_read_sens(filename, ...)  % for electrodes
  Additional options should be specified in key-value pairs and can be
    'fileformat'     = string, see the list of supported file formats (the default is determined automatically)
    'senstype'       = string, can be 'eeg' or 'meg', specifies which type of sensors to read from a fif file (default = 'eeg')
    'coordsys'       = string, 'head' or 'dewar' (default = 'head')
    'coilaccuracy'   = can be empty or a number (0, 1 or 2) to specify the accuracy (default = [])
  An electrode definition contain the following fields
    elec.elecpos = Nx3 matrix with carthesian (x,y,z) coordinates of each
    elec.label   = cell-array of length N with the label of each electrode
    elec.chanpos = Nx3 matrix with coordinates of each sensor
  A gradiometer definition generally consists of multiple coils per channel, e.g. two
  coils for a 1st order gradiometer in which the orientation of the coils is
  opposite. Each coil is described separately and a large "tra" matrix has to be
  given that defines how the forward computed field is combined over the coils to
  generate the output of each channel. The gradiometer definition constsis of the
  following fields
    grad.coilpos = Mx3 matrix with the position of each coil
    grad.coilori = Mx3 matrix with the orientation of each coil
    grad.tra     = NxM matrix with the weight of each coil into each channel
    grad.label   = cell-array of length N with the label of each of the channels
    grad.chanpos = Nx3 matrix with the positions of each sensor