Almost anyone knows that a measurement is the process of comparing a quantity with another one of the same type (e.g., length, volume, area) whose result is a number. Such a measurement can be done without ambiguities in a straightforward manner with the help of a measurement system, which requires speciŸc instrumentation for achieving such task . œis instrumentation can be a simple instrument for directly measuring a physical quantity (e.g., a voltmeter for measuring an electrical potential difference between two points of acircuit, an ampere meter for measuring acurrent žowing in abranch of acircuit, athermometer for measuring temperatures) and can take one of these following forms regarding their internal working and signal processing: analog or digital . œe ability toconnect and communicate with external devices  (using dedicated cables and/or communication networks) as well as the inherent žexibility  (their easiness for adding new functions and/or reconŸguration of the existing ones) makes digital instruments have major potential for use in several Ÿelds of human activity (heavy industry, medicine, transportation systems, domestic, agriculture, and food industry are some application examples). œe next evolutionary step of measurement instruments is integrating functions to provide wireless transfer of data. In this sequence of ideas, the developments of microelectronics and microsystems allowed engineers to successfully develop this new measuring method . œis resulted in new possibilities for measuring, acquiring, transferring, storing, and analyzing the physical world: embedded systems  and wireless sensors networks  are two new possibilities for achieving such a goal, with wireless being the major attractive technology. œis leads to the wireless instrument concept, which by its nature requires multidisciplinary concepts such as measurement science, electronic circuits design, microelectronics and microsystems fabrication, wireless communication systems, and networking . Figure 85.1 reinforces this idea by showing the di¥erent disciplines that must be employed for designing a wireless instrument. œe primary focus of this chapter is the presentation and integration of these concepts. œis chapter also presents biomedical applications based on wireless instruments and new application concepts.