Hi, the thermo inkjet process, which my hp 2130 printer has is briefly described here
The team at HP found that thin-film resistors could produce enough heat to fire an ink droplet. Two years later the HP and Canon teams found out about each other's work.[4][5]
In the thermal inkjet process, the print cartridges consist of a series of tiny chambers, each containing a heater, all of which are constructed by photolithography. To eject a droplet from each chamber, a pulse of current is passed through the heating element causing a rapid vaporization of the ink in the chamber and forming a bubble, which causes a large pressure increase, propelling a droplet of ink onto the paper (hence Canon's trade name of Bubble Jet). The ink's surface tension, as well as the condensation and resultant contraction of the vapor bubble, pulls a further charge of ink into the chamber through a narrow channel attached to an ink reservoir. The inks involved are usually water-based and use either pigments or dyes as the colorant. The inks must have a volatile component to form the vapor bubble; otherwise droplet ejection cannot occur. As no special materials are required, the print head is generally cheaper to produce than in other inkjet technologies.
The above being the case, let me know, whether refill is possible for this kind of cartridges, which is way ahead in inkjet technology