Non-return microvalve using low temperature co-fired ceramic (LTCC)

LTCC is a known suitable platform for microfluidic systems. We have developed actuation-less non-return valve for gases and liquids, which is based upon the inlet and reverse pressure. This work compares three different designs of such valves. In these designs, top lid and bottom cavity layer together forms micro fluidic channel, through which fluid or gas can flow. The pressure based movable ceramic part and the matching cavity at the inlet plays an important role in the valve designs. The designs are such that the liquid or gas flows from inlet to outlet without any difficulty. However, if the liquid or gas flows in reverse direction (i.e. from outlet to inlet) the movable part blocks the path at the cavity and opposes the liquid or gas flow through the channel. Two designs are based upon vertical motion of the movable ceramic part and has a `O´ ring to rest to movable part at the inlet side. One of these designs usesZirconia (ZrO₂) ball (design 2) while another has square shape (design 3) as the movable parts. Yet another design (design 1) is based upon sliding motion and teflon coating for lubrication. The initial testing using pressurised air (up to 6 bar) indicated that the reverse direction blockade is the best for design 2, which has shown leak rate of 3 ml min^-1 at 6bar pressure. This is followed by design 3 and by design 1, which have shown leak rates of 30 ml min^-1 and 100ml min^-1 respectively.