We developed a MEMS-based hydraulic displacement amplification mechanism (HDAM) with completely encapsulated liquid that can be used in applications that require large-displacement micro-actuators, such as tactile displays and microvalves controlling large mass flows. The HDAM contains a microcavity that is sealed by easily deformable thin polydimethylsiloxane (PDMS) membranes encapsulating an incompressible fluid and whose input and output surfaces have different cross-sectional areas. A displacement applied to the input surface is amplified at the smaller output surface. We patterned silicon wafers, bonded them to form the microcavity, and encapsulated glycerin within the microcavity by using ultraviolet curable resin as an intermediate layer and bonding easily deformable thin PDMS membranes to the silicon structure in a glycerin solution. This bonding-in-solution approach ensures that the encapsulated glycerin is bubble-free. We obtained fifteen-fold of amplification of the input displacement applied by a piezoelectric actuator and demonstrated a 3 × 3 array of actuators displaying rewritable Braille cells.
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