Ultrasonic device

1. A device for nondestructive measurement of stiffness of a material, comprising:

a printed circuit board (PCB);

one piezoelectric transmitter soldered onto the printed circuit board, wherein the piezoelectric transmitter has an area between 1-10 mm 2 , wherein the piezoelectric transmitter is configured to be connected to a function generator that is capable of generating an AC pulse;

one piezoelectric receiver soldered onto the printed circuit board, wherein the piezoelectric receiver has an area between 1-10 mm 2 , wherein the piezoelectric receiver is configured to be connected to an oscilloscope; and

one cover comprising a top side, a bottom side, and an opening configured to load a material to be measured for stiffness, wherein the bottom side is configured to face the printed circuit board, wherein the top side comprises a parylene-C coating to serve as biocompatible barrier and provides electrical passivation on the surface of the printed circuit board.

2. The device of claim 1 , wherein the distance between the piezoelectric transmitter and the piezoelectric receiver is between 2-10 mm.

3. The device of claim 1 , wherein the distance between the piezoelectric transmitter and the piezoelectric receiver is between 4-6 mm.

4. The device of claim 1 , wherein the parylene-C coating has a thickness between 1-50 μm.

5. The device of claim 1 , wherein the parylene-C coating has a thickness between 1-10 μm.

6. The device of claim 1 , wherein the piezoelectric transmitter and the piezoelectric receiver have same size.

7. The device of claim 1 , wherein the cover is made of a hard material.

8. The device of claim 1 , wherein one additional soft gasket is placed between the cover and the printed circuit board, wherein the soft gasket has an opening with the same size as the size of the opening of the cover.

9. A method of using the device of claim 1 to measure stiffness of a material, wherein the method comprises:

providing the device of claim 1 ;

providing a signal generator;

providing an oscilloscope;

providing a stiffness calibration curve;

providing a material to be placed on the cover opening with the parylene-C coating to measure its stiffness;

generating an AC pulse signal with the signal generator to the piezoelectric transmitter to provide an ultrasonic wave that propagates through the material to be tested to the piezoelectric receiver to generate an electrical signal; and

analyzing attenuation of the ultrasonic wave received by the piezoelectric receiver to provide stiffness of the material to be tested.

10. The method of claim 9 , wherein the material to be tested is a soft material.

11. The method of claim 9 , wherein the material is an extracellular matrix.

12. The method of claim 9 , wherein the method is capable of measuring a material with a stiffness range from 4 to 310 KPa.