Biomedical sensors couple physiological variables in living and other biologic systems to electronic instrumentation for making measurements. Microfabrication technology such as used in the microelectronics industry has been applied in the fabrication of biomedical sensors. Thin- and thick-film processing is especially well-suited to fabricating physical and chemical sensors due to the special properties of these films and the relative low costs for their production compared to other microfabrication technologies. These technologies can yield reproducible, batch-fabricated, and relatively inexpensive sensors that can be applied to biomedical problems in a cost-effective way. Devices such as biopotential electrodes, chemical sensors, temperature sensors, and transducers for measuring force and displacement can be fabricated using these techniques, and their small size and relatively low cost makes them especially useful for biomedical applications. The use of thick-film technology to fabricate a miniature chemical sensor to aid in diagnosing bacterial vaginosis will illustrate how this technology can be used in non-conventional ways in a medical application. The reliable measurement of infant breathing using sensors fabricated with thin-film technology will be presented as an example of the use of this technology in patient monitoring. A multidisciplinary approach makes it possible to study biomedical sensors from fundamental underlying principles through biomedical applications.