Fig. 1. Schematic of the PAI. (a) Physical model; (b) process flow diagram

Fig. 2. Different types of MEMS mirror contained in the hand-held PAI system. (a) Schematic of hand-held PAM probe based on two-axis water-immersible MEMS mirror^[5]; (b) schematic of the MEMS mirror actuated by the magnetic force^[19]; (c) schematic of the MEMS mirror actuated by the thermal expansion induced by the electric current^[27]

Fig. 3. Schematic and structure of the wearable PAI system. (a) Schematic of the light delivery and ultrasound detection in the W-PAT system^[33]; (b) schematic of the ultra-compact and W-OR-PAM system^[38]

Fig. 4. Schematic and structure of the portable PAI system^[5]. (a) Schematic of dual modality portable W-PAT system, in which both OR-PAM and OCT are included; (b) corresponding 3D image of the system

Fig. 5. Schematic and structure of the PAE system^[42]. (a) Schematic of OR-PAE system based on the MEMS mirror; (b) details of the OR-PAE probe