Definition of "bipolarly"

It is usually recorded from electrodes on the scalp. It can be recorded bipolarly from two electrodes placed over the same part of the cortex, or monopolarly with one “active” electrode over the cortex and a second “reference” electrode on some other part of the head.

2013, Leslie B. Cohen, Infant Perception: from Sensation to Cognition: Basic Visual Processes‎

A ground electrode located between Fpz and Fz. The electro-oculogram (EOG) was recorded bipolarly from two electrodes placed at the outer canthi of the right eye and below the left eye.

2015 August 26, “Effects of Relaxing Music on Mental Fatigue Induced by a Continuous Performance Task: Behavioral and ERPs Evidence”, in PLOS ONE‎