A method includes forming a hole in a first wafer and forming a sensor structure in or on a second wafer. The second wafer includes a piezoelectric material. The method also includes bonding the first wafer and the second wafer, where the sensor structure is located between the wafers. The method further includes forming a sensing layer by depositing material between the wafers through the hole in the first wafer. The sensing layer could be formed by depositing a sensing layer material on the second wafer using direct printing. Also, the hole through the first wafer could be formed using ultrasonic milling, micro-drilling, laser drilling, wet etching, and/or plasma etching. A spacer material could be used to bond the wafers together, such as frit glass paste or an organic adhesive. Trenches could be formed in the first wafer to facilitate easier separation of multiple sensors.