Fig. 10.

(a) Photograph of the proposed photoacoustic sensor that can fit in the palm of one’s hand. Reproduced with permission from Ref. [109], A: PA signal input, B: amplifier, C: rectifier, D: Arduino board, and E: display, (b) photoacoustic cell. Its mass is 1.70 kg. (1) The box which contains the electronics and the batteries, (2) photoacoustic cell with an embedded microphone, a laser diode and a photodiode, (3) standard 3.5 mm stereo connectors. Reproduced with permission from Ref. [110], (c) photograph of the miniature DAQ and control dedicated for PA measurements. Reproduced with permission from Ref. [111], (d) a photograph of the delay-line module. Reproduced with permission from Ref. [112].