Extra precaution is needed for sensors designed for in vivo applications. In vivo systems are difficult to remove once implanted. Given this fact, multiple backup strategies must be integrated into the system in the event of a single point failure. Redundancy of the sensing units can ensure failure of some of the sensors does not compromise the integrity of the system. The burden the bandwidth from the additional units can also be circumvented with careful hardware design and sophisticated software algorithms. The human body is a harsh and hazardous environment, where temperature and body fluid can affect the optimal performance of the smart instrument. A typical approach for implantable devices is to isolate and protect the sensors within the implants. Special treatments such as a bio-coating can also be applied to the implants to prevent bacteria adhesion to the implant surface, which may lead to infection. A bio-coating is a thin layer of biocompatible material that can be coated on a sensor, implant, or even food utilizing various coating technniques such as plasma sprays, chemical vapor deposition, or even manual dipping in a solution of bio-coating material. In orthopedics, bio-coatings such as calcium phosphate faciliate reattachment of an implant to a paitent’s bone. Specific coatings can also prevent restenosis and thrombosis. Bio-coatings also play an important role in bio-chemical sensing. It can protect a biosensor from ‘fouling’ by other proteins. There are two common methods used to power an embedded RF system: use of a battery and inductive powering. With the continuous development of low power
biosensors, most of the current medical devices operate between 1.8V to 5V, which can be powered with rechargeable batteries. In some instances, such as implantable devices, it is impossible to replace the batteries and inductive powering must be used. Figure 3 shows an example of an in vivo smart instrument powered through inductive coupling. Inductive powering uses two inductively