There is provided a test strip for testing a fluid sample, including a sample cavity configured to receive the fluid sample and an ultrasonically-spread reagent layer arranged on at least one surface of the sample cavity. There is also provided a method for making a biosensor, including providing a substrate having a region for receiving a sample; dispensing a liquid substance on at least one surface of the region for receiving a sample; and subjecting the substrate to ultrasonic vibrations to quickly and uniformly spread the liquid substance on the at least one surface of the region for receiving a sample.