Now, the printing head structure of inkjet printers, including photo machines, must be more widely used in micromechanical electronic systems, and the applications of micromechanical systems are entering different fields, not limited to printing, and the current micro scale devices will be quickly transferred to nanoscale devices, thus facing higher energy requirements. Heat dissipation will be the main problem in the future. The hot inkjet printing head is pursuing better nozzle arrangement density and higher ink drop frequency associated with the decrease of ink drop weight, required to operate at about W power, and the power requirements of some areas even reach or exceed w. While improving the basic structure power, we also need higher power density, for example, more than W per square meter.
Beyond the printing target, other applications of thermal inkjet technology are increasing day by day, such as the accurate incorporation of compounds and fuel injection. Although the basic principles of these new applications are the same as those of thermal inkjet printing, due to the very different nature of fluid and ink, the operation temperature is obviously different. The chip used in the laboratory is dependent on the precise fluid path and heater, providing a redesign process for the long period operation time and manufacturing cost requirements for the thermal inkjet technology. One of the examples is the polymerase chain reaction process, which multiplies the block DNA samples by the chain reaction. The process involves multiple temperature points, heating and cooling alternately.
For example, it is first to heat s to reach the degree of excess, to change the essence of the DNA or to break the double helix structure into two single twisted helices; then the primary "annealing" step is followed to require the cooling to - 60 degrees within about Imin to obtain the required DNA twisted "template" region; finally, the primary expansion process, heating The temperature of the target is around. The key of the problem is that we must change as fast as possible and change from one step to another, so as to achieve good output goals. In general, laboratory chips can provide the required production efficiency with over excessive heating rate per second and cooling rate per second. The changes in steps require only a fraction of a second. Temperature control is equally important for heating rate. The method of cavity meat placement can be realized by keeping closed loop feedback information. However, the uniformity of temperature must be guaranteed, although silicon can ensure an ideal hot cavity, but because of its high thermal conductivity, professionals are faced with a challenge, which requires micromachining to achieve isolation of the cavity to maintain the uniformity of the temperature.
The processing method for circulating heated cavity is attributed to ablation or etching of fluid pathways in different regions, for example, the fluid containing DNA samples will pass through different regions slowly and zigzag, each region corresponds to one of the three steps necessary for the polymerase chain reaction process, and the fluid motion is obtained by the action of the micropump. A bubble that uses heat to drive a fluid.
A large number of micromechanical electronic systems are currently used as the driving force of the target function, such as microcalorimeter used for biomolecular recognition, thermal micropumps (using heat generated microbubbles to move the fluid at a certain speed, velocity from less than a minute to a few liters per minute) and micro valves, or based on heat shock. The electrothermal actuator based on the bimetallic film or titanium nickel alloy is subjected to plastic deformation, and the original shape is restored by laser.
