Indicatore di temperatura a risposta impedenziometrica integrabile in sistemi RFID HF in forma di transponder RFID con chip o chipless e metodo di realizzazione di tale indicatore di temperatura

The present invention relates an RFID transponder (1 ) comprising means for detecting (11 ) the exceeding of a threshold temperature, wherein said RFID transponder (1 ) comprises a dielectric substrate (S), and an antenna (10) arranged on said dielectric substrate (S), and wherein said detection means (11 ) are arranged on said dielectric substrate (S) and are electrically and physically interfaced with the armatures of an interdigitated capacitor connected to said antenna (10), said RFID transponder (1) being characterised in that said detection means (11 ) comprise a multilayer dielectric structure (D) arranged on said dielectric substrate (S), and a protective layer (A) contacting said multilayer dielectric structure (D), covering and exerting a pressure on said multilayer dielectric structure (D), in the direction of said dielectric substrate (S), wherein said multilayer dielectric structure (D) comprises a first dielectric layer (D1 ) contacting said dielectric substrate (S), and a second dielectric layer (D2) arranged on said first dielectric layer (D1 ) and separated from said dielectric substrate (S), wherein said first dielectric layer (D1 ) comprises a material conformable by pressure and having a melting temperature equal to said threshold temperature, and wherein said second dielectric layer (D2) comprises permeable means capable of absorbing by capillarity said material of said first dielectric layer (D1 ), in its molten state, and further comprising two interdigitated electrodes (E1, E2) to form a capacitive transducer, arranged on said dielectric substrate (S), wherein said material of said first dielectric layer (D1 ) contacts said two electrodes (E1, E2) and said permeable media are separated from said material of said first dielectric layer (D1 ) and from said interdigitated electrodes (E1, E2), in such a way that, when said dielectric substrate (S) is heated to temperatures greater than said melting temperature of said material of said first dielectric layer (D1 ), said material melts and permeates by capillarity said permeable means, varying the resulting average dielectric permittivity of said multilayer dielectric structure (D) and consequently the electrical impedance of the interdigitated capacitor having as armatures the electrodes (E1, E2). The present invention also relates to a method for making an RFID transponder (1) comprising means (11) of detecting that a threshold temperature has been exceeded.