Abstract: An ultrasonic sensing device includes a housing, a piezoelectric assembly, a board and a plurality of fixing members. The housing includes a connecting board being a metal board and a supporting shell being a plastic member. The supporting shell includes a bottom wall opposite to a disposing opening of the connecting board and a surrounding side wall integrally surrounding and connecting to the bottom wall. The surrounding side wall encloses a portion of the connecting board. The piezoelectric assembly includes an encapsulating body and a piezoelectric sheet enclosed by the encapsulating body. The encapsulating body is disposed on the bottom wall and surrounded by the surrounding side wall. The piezoelectric sheet has a sensing surface exposed to the encapsulating body and facing the bottom wall. The fixing members fix the board on the connecting board, thereby pressing the sensing surface of the piezoelectric sheet to the bottom wall.

Abstract: An ultrasonic sensing device includes a housing, a piezoelectric assembly, a board and a plurality of fixing members. The housing includes a bottom wall, a top wall and a surrounding side wall connected between the top wall and the bottom wall. The piezoelectric assembly includes an encapsulating body and a piezoelectric sheet, wherein at least a portion of the piezoelectric sheet is enclosed by the encapsulating body and has a sensing surface exposed to the encapsulating body and facing the bottom wall. The board is disposed on the top wall of the housing and has a pressing surface facing the encapsulating body and the top wall. The plurality of fixing members is configured to fix the board to the top wall of the housing to press the board to the encapsulating body of the piezoelectric assembly, thereby pressing the sensing surface of the piezoelectric sheet to the bottom wall.

Abstract: An ultrasonic sensing apparatus includes an accommodating shell and at least one detection device. The accommodating shell includes a base and a convex portion connected to the base. A side of the base has a first detection opening toward a first direction, and a side of the convex portion has a second detection opening toward a second direction. Each of the at least one detection device is disposed in the base or the convex portion of the accommodating shell and includes a board, a piezoelectric assembly, a housing and a plurality of fixing members. The plurality of fixing members are configured to fix the board on the top wall of the housing to press the board to the encapsulating body of the piezoelectric assembly, thereby pressing the piezoelectric sheet to the bottom wall.

Abstract: A liquid concentration detecting device including a first substrate, a first temperature sensing element and a concentration sensor is provided. The first temperature sensing element and the concentration sensor are respectively disposed on opposite first surface and second surface of the first substrate. The concentration sensor includes a second substrate, a porous element, a heating element and a second temperature sensing element. The second substrate is disposed above the second surface. A portion of the liquid flows into the concentration sensor through the porous element, and the heating element heats the liquid in the concentration sensor. The second temperature sensing element measures the temperature variation of the liquid in the concentration sensor. The measured temperature and the temperature variation are compared to deduce a concentration of the liquid under detection.