application_controller.rb

class ApplicationController < ActionController::Base
  ...
  ...
  include DeviseCustomParams
end

devise_custom_params.rb

#devise_custom_params.rb is in app/controllers
module DeviseCustomParams
  included do
    before_action :configure_permitted_parameters, if: :devise_controller?
  end

  protected

  def configure_permitted_parameters
    devise_parameter_sanitizer.permit(:sign_up, keys: [:student_id, :professor_id, :name])
  end
end