A new method to produce formulations of bacterial cellulose that exhibit improved viscosity-modifying properties particularly with low energy applied to effectuate viscosity changes therewith is provided. The slit is formed so as to include a portion of the base in the vicinity to the vibration unit. The first evaluation signal is supplied to the pressure generating element to measure a first ejected amount of the first liquid droplet. Moreover, the thread surface is used to increase the contact area, hence reducing abrasion between components, extending lifetime, saving unnecessary components, and lowering the manufacturing cost.