Pseudosurface acoustic waves in hypersonic surface phononic crystals

Nardi, Damiano; Banfi, Francesco; Giannetti, Claudio; Revaz, B.; Ferrini, Gabriele; Parmigiani, F.

doi:10.1103/physrevb.80.104119

Cited by 48 publications

(61 citation statements)

References 35 publications

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“…SAW resonators have working frequencies up to GHz frequencies and the lattice constant goes down to micrometers and even micrometers [22,25,26]. Some authors have even explored the possibility of designing dual phononic-photonic crystals, these structures are called phoxonic crystals and they are used to study the simultaneous control of the propagation of acoustic and electromagnetic waves [23,[27][28][29].…”

Section: (B)mentioning

confidence: 99%

Fully-disposable multilayered phononic crystal liquid sensor with symmetry reduction and a resonant cavity

et al. 2017

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. Fullydisposable multilayered phononic crystal liquid sensor with symmetry reduction and a resonant cavity. Measurement: Journal of the International Measurement Confederation, 102, pp. 20-25. doi: 10.1016Confederation, 102, pp. 20-25. doi: 10. /j.measurement.2017 This is the accepted version of the paper.This version of the publication may differ from the final published version. Permanent b s t r a c tPhononic crystals are artificial structures with unique capabilities to control the transmission of acoustic waves. These novel periodic composite structures bring new possibilities for developing a fundamentally new sensor principle that combines features of both ultrasonic and resonant sensors. This paper reports the design, fabrication and evaluation of a phononic crystal sensor for biomedical applications, especially for its implementation in point of care testing technologies. The key feature of the sensor system is a fully-disposable multi-layered phononic crystal liquid sensor element with symmetry reduction and a resonant cavity. The phononic crystal structure consists of eleven layers with high acoustic impedance mismatch. A defect mode was utilized in order to generate a well-defined transmission peak inside the bandgap that can be used as a measure. The design of the structures has been optimized with simulations using a transmission line model. Experimental realizations were performed to evaluate the frequency response of the designed sensor using different liquid analytes. The frequency of the characteristic transmission peaks showed to be dependent on the properties of the analytes used in the experiments. Multi-layered phononic crystal sensors can be used in applications, like point of care testing, where the on-line measurement of small liquid samples is required.

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Section: (B)mentioning

confidence: 99%

Fully-disposable multilayered phononic crystal liquid sensor with symmetry reduction and a resonant cavity

et al. 2017

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“…A critical issue is the evaluation of the frequency of the pseudo-SAW solution u SAW , in relation to its strong surface confinement, calling for calculations beyond a perturbative approach. 9 We positively tested the reliability of the adopted framework in the hypersonic frequency range by benchmarking it against measurements reported by Siemens et al 8 for Ni on sapphire SPCs working up to 47 GHz, as shown in Fig. 1.…”

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confidence: 99%

“…and radiates elastic energy into the bulk. 9 The generated pseudo-SAW acoustically modulates the SPC, which serves as an optical phase diffraction grating for a second time-delayed EUV laser pulse with wavelength λ probe ∼ p. The EUV pulse hence probes the frequency ν 0 of acoustic modulation. The relative variation in the time-domain of the diffracted probe signal ∆I 1d /I 1d , as measured on the first order of diffraction spot 12 to improve the sensitivity with respect to standard reflection measurements, 13 oscillates at the pseudo-SAW frequency ν 0 .…”

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Design of a surface acoustic wave mass sensor in the 100 GHz range

Nardi

Zagato

Ferrini

et al. 2012

Applied Physics Letters

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A design for photoacoustic mass sensors operating above 100 GHz is proposed. The design is based on impulsive optical excitation of a pseudosurface acoustic wave in a surface phononic crystal with nanometric periodic grating, and on time-resolved extreme ultraviolet detection of the pseudosurface acoustic wave frequency shift upon mass loading the device. The present design opens the path to sensors operating in a frequency range currently unaccessible to electro-acoustical transducers, providing enhanced sensitivity, miniaturization and incorporating time-resolving capability while forgoing the piezoelectric substrate requirement.The field of microscale mass sensors has been booming recently, driven by the advances in nanopatterning techniques and the increasing request for devices capable of minute amounts of matter detection, most notably for biological and environmental interests. A variety of sensors have been implemented, among them surface acoustic waves (SAW)-based devices. 1,2A SAW is an elastic wave that propagates confined to the surface of a semi-infinite medium, the penetration depth being a fraction of its wavelength λ = v SAW /ν, with v SAW and ν as the SAW velocity and frequency, respectively. The interaction with any medium in contact with the surface affects frequency and lifetime of the wave itself. As the SAW frequency ν increases, so do its surface confinement (∼λ −1 ) and the device's sensitivity to mass loading.In typical SAW-based devices, SAWs are launched and detected via two interdigital transducers (IDT) patterned on a piezoelectric substrate. Upon mass loading the free surface between IDTs, the unperturbed SAW frequency ν 0 shifts downward of an amount ∆ν. Measurement of ∆ν/ν 0 enables quantification of the bound mass. 3 These devices perform well in terms of ∆ν, but the drawbacks are the maximum operating frequency bounded to the GHz range due to speed limits in the electronics, the lack of fast temporal resolution, and the piezoelectric substrate requirement.A strategy is here outlined to overcome these limitations. It relies on all-optical generation of a pseudosurface acoustic wave (pseudo-SAW) in a hypersonic surface phononic crystal (SPC), 4-6 and on time-resolved extreme ultraviolet (EUV) detection of the pseudo-SAW frequency in a diffractive scheme. 7,8 The device we propose relies on a SPC made of periodic Al stripes (Ni stripes are also investigated) deposited on sapphire (stripes' periodicity p = 50 nm, height h = 2 nm, filling fraction f = d/p = 0.2, mass density ρ Al = 2700 Kg/m 3 ). The stripes' width d ∼ 10 nm is within reach of state of the art e-beam lithography. The pseudo-SAW frequency ν 0 , set by v SAW /p, is expected to shift of ∆ν upon mass loading the SPC, 9 enabling mass detection. The present scheme gives access to operating acoustic frequencies beyond 100 GHz, enhancing the device's sensitivity, incorporates ultrafast time-resolving capabilities, forgoes the piezoelectric substrate requirement, and allows for increased miniaturization with respect to standa...

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“…In order to spot out the solutions characterized by an interface-confined displacement field in the PDMS-SPC, the SAW-likeness coefficient a(f) is calculated for each eigenmode. 29 The SAW-likeness coefficient identifies eigenmodes with mechanical energy confined in close proximity of the interface. The calculation is here performed taking aðf Þ ¼ hE A ðf Þi= hE tot ðf Þi, with hE A ðf Þi and hE tot ðf Þi being the time-averaged mechanical energy contents of the eigenmode at frequency f in domain A and in the entire PDMS-SPC unit cell, respectively, as illustrated in the inset of Figure 3(b).…”

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confidence: 99%

Interface nano-confined acoustic waves in polymeric surface phononic crystals

Travagliati

Nardi

Giannetti

et al. 2015

Applied Physics Letters

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The impulsive acoustic dynamics of soft polymeric surface phononic crystals is investigated here in the hypersonic frequency range by near-IR time-resolved optical diffraction. The acoustic response is analysed by means of wavelet spectral methods and finite element modeling. An unprecedented class of acoustic modes propagating within the polymer surface phononic crystal and confined within 100 nm of the nano-patterned interface is revealed. The present finding opens the path to an alternative paradigm for characterizing the mechanical properties of soft polymers at interfaces and for sensing schemes exploiting polymers as embedding materials.

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Pseudosurface acoustic waves in hypersonic surface phononic crystals

Cited by 48 publications

References 35 publications

Fully-disposable multilayered phononic crystal liquid sensor with symmetry reduction and a resonant cavity

Fully-disposable multilayered phononic crystal liquid sensor with symmetry reduction and a resonant cavity

Design of a surface acoustic wave mass sensor in the 100 GHz range

Interface nano-confined acoustic waves in polymeric surface phononic crystals

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