As described above, in Sample 6, since both the support and the heat generating layer have flexibility, a pressure wave generating element having the flexibility can be realized. Therefore, the degree of freedom of the installation condition of the pressure wave generating element is increased, and for example, the pressure wave generating element can be used by being attached to a curved base.

(Sample Preparation Method)

A pressure wave generating element was produced by the following method (Samples 7 to 19).

A polyvinylidene fluoride (PVDF) solution prepared using a mixed solvent of N,N-dimethylformamide (DMF) and acetone (DMF:acetone=6:4) as a solvent was used as a spinning solution. The solution concentration was adjusted to 3 wt % to 20 wt %. The fiber diameter obtained by electrospinning can be controlled by adjusting the solution concentration.

Spherical or spheroid beads as illustrated in FIG. 7 may be formed in the fiber by lowering the concentration and viscosity of the solution, but the beads can be contained in the fiber membrane used for the pressure wave generating element (Samples 11, 14, 17, 18, and 19). The size of the beads is 0.5 to 3.0 μm in short diameter. In addition, the beads may have a hollow spherical shape or a long spherical shape. On the other hand, in order to obtain fibers in which generation of beads was suppressed in a low concentration solution, lithium chloride was added to the solution in an amount of 1.0 wt % with respect to the polymer weight (Samples 12, 13, 15, and 16). In addition, tetrabutylammonium chloride, potassium trifluoromethanesulfonate, or the like can be used as an additive.