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...rain/deformation, its electromagnetic resonance frequency may change accordingly.sSuchschange can be interrogated by a wireless reader and used as the strain indicator. Jia et al. [10] and Loh et al. =-=[11]-=-sdeveloped inductively coupled wireless strain sensors to measure the shift of resonance frequency under tensile strain.sThe experimental results showed linearity between the resonance frequency shift...

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...in film’s frequency-domain equivalent resistance exhibits a bilinear response to pH, where lower sensitivity is observed for acidic pH solutions (1 kΩ-pH-1) but dramatically increases when exposed to basic solutions (15 kΩ-pH-1 as shown in Figure 9). It should be noted that no obvious trends are identified for capacitance change with varying pH but rather remains constant at 1.7 pF. These results suggest a parallel resonant circuit configuration can achieve maximum RFID bandwidth change as a function of pH (Equation 3b). PASSIVE WIRELESS PH SENSING In a previous study conducted by Loh, et al. [26], nanocomposite strain and pH sensors have been coupled with 45 and 70 mm coil antennas formed from wound magnetic wire for validating passive wireless sensing and communications. Preliminary results indicate that an RFID reader can interrogate these sensors and detect system bandwidth change due to applied strain (±10,000 µε) or pH (1 to 10). However, the large form factor of these coil antennas makes them unrealistic for embedment within structural components. As a result, the main objective of this study is to take advantage of the versatility of LbL to deposit nanocomposite sensors on subs...

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...d carbon nanotube- polyelectrolyte (SWNT-PE) composite sensors to measure strain in concrete structures, the sensors were then coupled with RFID tags to wirelessly measure their electrical resistance =-=[10]-=-. CNTs were also used to detect damage initiation in composite materials such as matrix microcracking and delamination. This was accomplished by embedding CNTs into the host structure to form conducti...

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...rain/deformation, its electromagnetic resonance frequency may change accordingly.sSuch changescan be interrogated by a wireless reader and used as the strain indicator.sJia et al. [16] and Loh et al. =-=[17]-=-sdeveloped inductively coupled wireless strain sensors to measure the shift of resonance frequency understensile strain. The experimental results showed linearity between the resonance frequency shift...

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...(usuallyswith 2D shape) is under strain/deformation, its EM resonance frequency can changesaccordingly.sSuch change can be interrogated by a wireless reader and used as a strainsindicator.sLoh et al. =-=[5]-=- developed inductively coupled wireless strain sensors tosmeasure the shift of resonance frequency under tensile strain, which shows ansapproximately relationship. Chen et al. [6] successfully develop...

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...erived. For example, wirelesssstrain sensors are developed using inductive coupling mechanism; the resonancesfrequency shift under tensile strain is shown to be approximately linear (Jia et al.s2006; =-=Loh et al. 2008-=-).sIn addition, a microstrip patch antenna for measuring strainsand detecting cracks in metallic structures is developed, based on EM backscatteringsmechanism (Tata et al. 2009; Deshmukh and Huang 201...

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...g applications. Many applications for passive wireless sensing have been realized in corrosion monitoring[1][2][3][4][5][6][7], temperature sensing[8], conductivity sensing[9][8][10][11], strain-gauge=-=[12]-=-, pH monitoring[12][7] etc. Non-destructive testing and evaluation is a mature field, in which inductively coupled wireless sensors are finding many applications that involve local parameter sensing. ...

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...ms whoseselectrical properties are sensitive to strain and PH changes. LBL assembled carbon nanotubescomposites have been used as strain sensors also in combination with wireless transmissionssystems =-=[23]-=- and to develop, in combination with the electrical impedance tomographystechnique, a sensing skin for crack detection and impact monitoring on structures [24].sInnovative applications concern the use...