The continuous dipping criteria of the contact printing for the microarray manufacturing with a slot pin

Contact printing is a widely used method to build microarrays. In contact printing, a slot pin picks up some solution and spreads it to the surface of the substrate point by point. Because of the limited volume, it is inevitable that the slot pin fails to spread the solution after certain points. The number of continuous dipping points has a dominant influence on the microarray manufacturing. In this paper, the criteria that the pin keeps continuous dipping are analyzed. Both the static model and dynamic model of the slot pin are discussed. The maximum distance from the holding solution to the substrate´s surface and the distance that the kinetic energy can overcome the work of the surface tension are supposed to judge the continuous printing. It is found that the angle from the pin´s central axis to the inner generatrix added with the contact angle of the solution should be less than 90° in order to pick up the solution. The width of the slot tip, the angle from the central axis to the inner generatix, the velocity of the pin, and the surface tension coefficient of the solution are the crucial factors for the continuous dipping. The criteria referred in this paper are useful for designing a slot pin or making a microarray.