The Gefitinib molecular weight physical properties of ink play important role in inkjet printing technology. For example, a low ink viscosity of about 20cP is favorable in order to have the appropriate amount and velocity of ink ejected from the nozzle. Surface tension of the ink will determine the spheroid shape of the ink after ejection, and is typically between 28mN?m?1 and 350mN?m?1. Molten metals typically have very high surface tension; meanwhile, structural polymers possess very low surface tension [91, 100]. Polymeric additives are used to improve dye bonding to the substrate and improve the ink viscosity. Humectants such as ethylene glycol are added at 10%�C20% to prevent clogging and drying of the nozzle. The surface tension of the ink is advised to be at a minimum of 35mN?m?1.
Examples of conducting polymers commonly used in inkjet printing are polyaniline (PANI) and PEDOT:PSS [92]. Figure 16 shows the inkjet profile of poly(ethylenedioxythiophene) (PEDOT) and poly(9,9-dioctylfluorene) (F8) aqueous solution being deposited onto a prepatterned substrate. Figure 15 illustrates the impact of the ink’s physical properties on the droplet profile. The formation of F8 long tail is seen from the stroboscopic image. The difference in profile is caused by the difference in viscosity, surface tension, and the polymer molecular weight of the respective solutions. Figure 16Comparison of (a) PEDOT and (b) F8 ink droplets [94].Printing quality is also controlled by substrates surfaces and ink interaction [91, 101]. Chemical modifications of substrates are a common practice in improving printing quality.
The hydrophilic character of substrates surfaces is controlled to prevent excessive absorption of liquids and inks. Surface porosity and roughness influence ink spreading onto the substrate. Synthetic polymer is produced to form a thin film on the substrates surfaces which promote better inkjet printing quality. Substrate treatments are found to be important in keeping excellent printing quality. It must be performed such that hydrophilic character of substrate is kept to allow surface wetting whenever necessary [101].As is the case with polymeric thermoelectric materials in general, the inkjet printing process is best suited for low temperature thermoelectric materials, for applications in ambient temperature such as hybrid solar cells, and body heat electricity generation.
Even higher resolutions may be attained using electrohydrodynamic jet printing, which allows for high resolution, precision, and speed printing [102]. Jet printing generates small scale droplets targeted GSK-3 on nano- and microscales researche. The use of ultrafine inkjet printer allows a minimum size of dots of less than one micron, thus allowing fabrication of materials and devices using inkjet printing, which enter the realm of nanotechnology [103].