Figure 2: Typical noise levels and background signals for the microphone set-up.

(a) For the empty trap, identical noise levels and background signals are recorded for a pure TEG solvent droplet in the trap (data not shown). (b) With a VIS441/TEG solution droplet in the trap. At t=0 s, the excitation laser (445 nm) is switched on and at t=7 s the trapping laser is switched off.