Sistema híbrido CMOS e sensores a nanotubos de carbono para etiquetas RFID.

Abstract

The fast market diffusion of Radio-Frequency Identification systems (RFID) occurred in recent years has driven the emergence of new applications and needs in many fields of human activity. At the same time, technological developments have greatly expanded the universe of features and functionalities which can be added to RFID tags, originally designed to provide only an identification code and carry a small amount of data. Among these new applications, the use of passive RFID tags as sensing devices attract particular attention due to the technical challenges involved as well as the market potential of such solution. Naturally, the technical challenges involved in the integration of RFID sensor tags are not the same for different types of sensors. The integration of gas sensors to passive RFID tags is a challenge especially difficult to overcome. Such devices are typically consumes a great amount of energy, occupy a high volume for a common label and its manufacturing is, in most cases, incompatible with the CMOS process used to manufacture the tag circuit. In addition, gas sensors are subject to contamination, requiring periodical cleaning and calibration procedures, which is very inconvenient since it commonly requires laboratory facilities for its realization. Because of these difficulties, the few existing solutions only partially solves the problem, and are mostly incompatible with current RFID standards, which makes difficult its commercial adoption. This paper presents a new solution to integrate gas sensors to passive RFID tags. The proposed solution involves a hybrid CMOS and carbon nanotube system integrated into an RFID tag, capable of performing specific gas sensing operations as well as to autonomously clean the sensor by a remote command. Furthermore, the system comprises multiple external sensors, includes an internal temperature sensor and supports the remote adjustment and calibration of each sensor. The proposed solution overcomes the problems and limitations identified in previous solutions and keeps, at the same time, the compatibility with current RFID standards.