An ink delivery device, method and non-transitory computer readable medium, the device may include a first closed pathway for a first ink flow through a multi-nozzle printhead in a first direction, and a second closed pathway for a second ink flow through the multi-nozzle printhead, the second pathway configured to move the second ink flow in a second direction. A seal formed between the outer component and the inner component and wherein the front face includes a conduit, which leads radially outward and is located lower with respect to the front face. An electrically-conductive component extends from one electrode to the other in contact with the phase-change material. A transmitted light getting out of the droplet S downward is introduced to a diffraction grating 19 through a window plate 17 and a slit 18, and dispersed in a wavelength dependent manner. The base may further include a separation facilitation structure between the first and second transition members and configured to facilitate separation of the first and second transition members.