Printing technologies recently have been applied to environmental pollution and food safety testing applications because there is more and more demand for inexpensive, portable and functional devices to be used for monitoring food and environment, such as enzyme-based biosensors [1] [2]. A system for printing nanoliter DNA based solution droplets on a lateral flow test strip with improved sensitivity for detection of Escherichia coli O157:H7 (E. coli O157:H7) is described in this article. We will present an overview of the results obtained with our printing process and the image analysis of the responses in the test strips. The printing process includes the precise control of droplet volume, the design of the print masks, and functional printing of the DNA-based solution. We create an image analysis system to read the responses of the test strips to the foodborne pathogens (Escherichia coli O157:H7) and determine the relationship between the responses and the concentration of the E. coli. Furthermore, we confirm that our printed test strips can successfully detect the presence of E . coli O157:H7 with a concentration as low as 10² CFU/ml.