Ultrasonic traveling wave micropump for liquid

Abstract

The invention relates to an ultrasonic traveling wave micropump for moving a liquid, said micropump comprising: two single linear piezoelectric transducers ( 2, 3 ); a flexible metal blade ( 4 ), each end portion of which rests on one of the two linear piezoelectric transducers; a sealable channel ( 5 ) that is made of shape-changing material and is intended for transporting the liquid from an inlet (E) to an outlet (S) of the micropump, said channel ( 5 ) resting longitudinally on said blade ( 4 ) between said linear piezoelectric transducers ( 2, 3 ); and an excitation means ( 7 ) for exciting at least the linear piezoelectric transducer ( 2 ) located near the inlet (E) of the micropump so that said transducer generates a transverse vibration in the blade ( 4 ) and the channel ( 5 ) along a traveling wave moving to the outlet (S) of the micropump.

1 . An ultrasonic traveling wave micropump for moving a liquid, said ultrasonic traveling wave micropump comprising:
 a. two separate linear piezoelectric transducers;   b. a flexible metal strip each end part of which rests on one of the two linear piezoelectric transducers;   c. a sealed channel made of a deformable material for transporting the liquid from an inlet to an outlet of the micropump, said channel lying on said strip longitudinally between said linear piezoelectric transducers; and   d. excitation means for exciting at least the linear piezoelectric transducer located near the inlet of the micropump so as it generates in the strip and channel a transverse wave vibration that travels toward the outlet of the micropump.   
     
     
         2 . The micropump as claimed in  claim 1 , wherein the linear piezoelectric transducer located near the outlet of the micropump is used to damp the transverse vibration. 
     
     
         3 . The micropump as claimed in  claim 2 , wherein the linear piezoelectric transducer located near the outlet of the micropump is connected to an RL load the resistance and inductance of which are chosen so as to reduce and even prevent reflection of the traveling wave. 
     
     
         4 . The micropump as claimed in  claim 2 , wherein the linear piezoelectric transducer located near the inlet is positioned a distance of 7λ/8 away from the nearest end of the strip, λ being the wavelength of the traveling wave, whereas the linear piezoelectric transducer located near the outlet is positioned a distance of 7λ/8+nλ/2 away from said left-hand end, n being a positive integer. 
     
     
         5 . The micropump as claimed  claim 1 , wherein the two piezoelectric transducers are used as vibrators in order to excite two consecutive vibration modes of the strip. 
     
     
         6 . The micropump as claimed in  claim 5 , wherein the excitation means simultaneously excite both linear piezoelectric transducers, one with a first sinusoidal electrical signal at an intermediate frequency relative to the frequencies of the two consecutive vibration modes, the other with a second sinusoidal electrical signal at the same intermediate frequency, but in quadrature phase with the first signal. 
     
     
         7 . The micropump as claimed in  claim 1 , wherein said sealed channel is bonded to the strip. 
     
     
         8 . The micropump as claimed in  claim 1 , wherein said sealed channel is a film made of polydimethylsiloxane. 
     
     
         9 . The micropump as claimed in  claim 1 , wherein the two piezoelectric transducers are Langevin structures. 
     
     
         10 . The micropump as claimed in  claim 9 , wherein each Langevin structure comprises an upper body with a conical shape, configured to both amplify the strain obtained at the top of the upper body, in the location where the strip rests, and to minimize the region of contact between the transducer and the strip. 
     
     
         11 . The micropump as claimed in  claim 1 , wherein said micropump furthermore comprises a base made of a material with an acoustic impedance chosen to prevent the vibrations from propagating through said base.