Many voltage-gated channels, for example voltage-gated sodium, potassium, and calcium channels, are sensitive to mechanical fluctuations in plasma membranes in response to electrical fields. These electrical fields modulate the ion channel's opening and membrane conductance occuring on millisecond timescales relevant to neuronal activity. Using pulsed radar techniques, brain activity can be modulated and data recovered in a variety of ways including thermoacoustic responses.
See https://neuroforlunch.github.io/thermoacoustic-waterfall/