Mechanical resonator optimization using shear wave damping
View Patent ↗Provided is a fingerprint sensor including one or more mechanical devices for capturing the fingerprint. The mechanical devices include a matrix of pillars and are configured to be mechanically damped based upon an applied load. A q factor of the pillars is optimized by adjusting a distance between pillars within the matrix in accordance with a quarter shear wavelength at an operating wavelength.
1. A fingerprint sensor, comprising:
one or more mechanical devices for capturing the fingerprint;
wherein the mechanical devices include a matrix of pillars and are configured to be mechanically damped based upon an applied load; and
wherein a distance between the pillars is a function of a quarter shear wavelength at an operating wavelength.
2. The sensor of claim 1 , wherein an interference of active neighboring pillars is minimized by interconnecting diagonal neighboring pillars with a pillar of interest and not connecting vertically or horizontally neighboring pillars with the pillar of interest.
3. The sensor of claim 1 , wherein a q factor can be improved by reducing an acoustic impedance of the matrix material, the reducing being facilitated by at least one of (i) reducing a density of the matrix material and (ii) reducing a stiffness of the matrix material.
4. The sensor of claim 3 , wherein the pillars are formed having a square cross-section.
5. The sensor of claim 3 , wherein the pillars are formed having an annular cross section.
6. The sensor of claim 1 , wherein each of the matrix pillars is electrically connected to one or more diagonally positioned adjacent pillars.
7. The sensor of claim 6 , wherein each of the matrix pillars is devoid of an electrical connection to linearly positioned adjacent pillars.
8. The sensor of claim 7 , wherein the matrix is formed of a porous polymer material.
9. A sensor, comprising:
a matrix formed of piezo-electric pillars;
wherein the pillars are configured for mechanical damping based upon an applied load;
wherein each of the pillars is electrically connected to one or more diagonally positioned adjacent pillars; and
wherein a distance between the pillars is a function of a quarter shear wavelength at an operating wavelength.
10. The sensor of claim 9 , wherein each of the matrix pillars is devoid of an electrical connection to linearly positioned adjacent pillars.
11. The sensor of claim 9 , wherein the matrix is configured to sense a load representative of a sensed fingerprint.