Ziapin 2 is a molecular optomechanical light transducer. Ziapin 2 is an amphiphilic azobenzene with a strong non-covalent affinity to the plasma membrane. Ziapin 2 can be used to photo-modulate the membrane potential in cells of the Gram-positive bacterium Bacillus subtilis. Ziapin 2 enters the lipid membrane very rapidly (≈ 40 ns).