Presentation on theme: "Inorganic Materials For Biomems Anne Samuel. Inorganic Materials Materials used for micropumps and valves Thin-Film Shape Memory Alloy(NiTi) Actuated."— Presentation transcript:
Inorganic Materials Materials used for micropumps and valves Thin-Film Shape Memory Alloy(NiTi) Actuated Micropump NiTi/Si Diaphragm Micropump Micromachined pump based on thick-film piezoelectric actuation.
Thin-Film Shape-Memory Alloy Actuated Micropump Shape memory alloys are ones which undergoes phase transformation from one phase(austenite) to an another phase( Maternsite). Used one way shape memory effect (OWSME) for actuation. Two actuation configurations to perform actuation- Polyimide-Spring-Biased actuator(Polyimide + TiNi) & Complementary Actuator ( TiNi+TiNi).
NiTi/Si Diaphragm Micropump Micropump actuated by NiTi/Si composite diaphragm. The recoverable force of NiTi thin film and biasing force of silicon membrane allows reciprocating motion of the pump. Structure of a unit SMA/substrate bimorph.
NiTi/Si Micropump Analysis of the actuation mechanism. Thermal expansion coefficients of Si and SMA are different. Depending on temperature, the bimorph structure will deform or be flat.
Thick-film Piezoelectric Actuation Micropump with thick film /silicon micromachined hybrid actuation. Actuation based on the flexure of screen printed PZT layer on Si membrane. Schematic of hybrid actuated micropump. Pump consists of top electrode, bottom electrode and PZT layer in the middle.
Thick-film Piezoelectric Actuation Experiment with different bottom electrodes. To find high dielectric values of PZT layer- gives good mechanical acutation performance. It was found that Au Cermet and evaporated Pt thin film gives good dielectric constant. Candidate in medicine as a cheap disposable pump for drug dispensing.
References Bernard.W, Kahn.H et.al. “ Thin-film shape memory alloy actuated micropumps”. Journal of Microelectromechanical system.1998. Vol 7. PP 245-251. Koch.H, Harris.N et.al. “A novel micromachined pump based on thick-film piezoelectric actuation”. Sensors and Actuators, 1998. Vol 70. PP 98-103. Xu.D, Wang.Li, et.al. “Characteristics and Fabrication of NiTi/Si diaphragm micropump”. Sensors and Actuators, 2001. Vol 93. PP 87-92.