Comparison of FBAR and QCM-D sensitivity dependence on adlayer thickness and viscosity

Abstract

Unlike the quartz crystal microbalance, which has been used extensively for the analysis of biochemical interactions, only few measurements with biochemical adsorbent have been done with film bulk acoustic resonators (FBAR). In this paper, the FBAR behaviour on exposure to a lipid vesicle solution and the formation of a polyelectrolyte multilayer structure is investigated and compared with the results obtained with the quartz crystal microbalance. Differences in the resonator response were found between the two techniques and depending on the resonators resonance frequency ranging from the MHz to the GHz regime. As an explanation, we suggest that the penetration depth and the influence on viscoelastic properties, which are both known to be frequency dependent, cause the variations in the results. As a consequence, the higher operating resonance frequencies of the FBAR increase the sensitivity to changes in the viscoelasticity of the adsorbent and also decrease the sensing length of the device. AbstractUnlike the quartz crystal microbalance, which has been used extensively for the analysis of biochemical interactions, only few measurements with biochemical adsorbent have been done with film bulk acoustic resonators (FBAR). In this paper, the FBAR behaviour on exposure to a lipid vesicle solution and the formation of a polyelectrolyte multilayer structure is investigated and compared with the results obtained with the quartz crystal microbalance. Differences in the resonator response were found between the two techniques and depending on the resonators resonance frequency ranging from the MHz to the GHz regime.As an explanation, we suggest that the penetration depth and the influence on viscoelastic properties, which are both known to be frequency dependent, cause the variations in the results. As a consequence, the operating resonance frequency was found to be an important parameter for the design of acoustic resonators as sensors.

AlN-based BAW resonators with CNT electrodes for gravimetric biosensing

“…However, higher frequency and smaller dimensions cause all of the environmental and boundary conditions to affect the operation of the tesonatots mote sttongly than the QCMs, tesulting in a highet noise level and lowet quality factots (Q). It is fot this teason that, to date, the tepotted empitical expetimentally detetmined mass sensitivity of thin film-based tesonatots is not significantly gteatet than that of QCMs [18][19][20].…”

“…In 1972, it was utilised for the first time to detect antibodies [11]. QCMs have a mass detection limit of a few nanograms, which is limited by low operation frequency (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) due to the quartz substrate thickness. In this respect, the utilisation of thin film technology to develop film bulk acoustic resonators (FBARs) and solidly mounted resonators (SMRs), extremely high frequency versions QCM with an operating frequency in the range of a few GHz, offers great potential to improve the sensitivity and detection limit of gravimetric sensors.…”

“…In the last few yeats thete has been significant wotk cattied out towatds the imptovement of the sttuctutal and electtical ptopetties of ZnO and A1N thin films fot theit use as the active material inthese devices [18][19][20][21][22][23][24] howevetthe Q_ factots ofthese tesonatots ate still lowet than those ofQCMs [25,26], limiting theit sensitivity.…”

Thin-film electro-acoustic sensors based on AlN and its alloys: possibilities and limitations

“…It is here pointed out that specifically, the shear mode AlN FBAR sensor for biochemical applications have been shown to offer a competitive alternative to the QCM with complementary properties (Nirschl et al 2011;Wingqvist 2010). Measured noise levels of a 1 GHz shear mode FBARs in contact with water showed the mass resolution to be in the range 0.3-7.5 ng/cm 2 which is similar to a 10 MHz QCM.…”

Active control scheme for improving mass resolution of film bulk acoustic resonators

“…Currently, two types of structures are designed for the FBARs to reduce the acoustic energy dissipation into the substrates [22] . The first type is a solidly mounted resonator (SMR) that is formed by isolating the resonator from the substrate with a Bragg reflector [12][13][14][15]19,[23][24] . The second one is an air cavity type resonator that is connected to the substrate only at the edges of the resonator [16][17][18]25] .…”