Enhancement of the thermoelastic component of the photoacoustic signal of silicon membranes coated with a thin TiO2 film

Markushev, D. K.; Markushev, D. D.; Aleksić, Slavoljub; Galović, S.; Ordoñez-Miranda, José

doi:10.1063/5.0079902

Cited by 11 publications

(2 citation statements)

References 18 publications

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“…Figures 4(a The value obtained from the classical model of f c3 = 4kHz was much lower than expected from the literature, around f c3 = 10kHz. Also, the damping factor δ c3 was expected to be around 0.6 [23,52]. Similar results of simulation for A400 sample are presented in Fig.…”

supporting

confidence: 78%

Thermal Fractional Diffusion: Experimental Evidence from the Discrepancies in the Amplitude and Phase in Photothermal Technique

Somer

Novatski

Cruz

et al. 2022

Preprint

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The photoacoustic (PA) signal is the pressure variation in the PA cell and by means of the open photoacoustic cell (OPC) technique, its amplitude and phase components are measured. In this work, the issue of disagreement between experimental measured amplitude and phase for AISI 316 samples with the expected theoretical result from the classical model is studied. The results of the thermal diffusivity obtained from amplitude are inconsistent with phase analysis. This work aims to show a way to get a unique value of thermal parameters from simultaneous analysis of the amplitude and phase of the PA signal. Also, the fractional models were applied to improve the fit of experimental data and provided results closed with the expected thermal diffusivity value.

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supporting

confidence: 78%

Thermal Fractional Diffusion: Experimental Evidence from the Discrepancies in the Amplitude and Phase in Photothermal Technique

Somer

Novatski

Cruz

et al. 2022

Preprint

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“…The plasmaelastic bending was ultimately disregarded due to the likelihood of short minority lifetimes (τ ) within the thin MEMS structures, greatly reducing the excess carrier density. Comparing thermal effects and plasmaelastic effects, previous works [39,40] suggested that plasmaelastic effects would only be relevant at high frequencies. Beyond this, the plasmaelastic bending in silicon often causes a shift in the output phase when going from sub-bandgap to superbandgap [41,42].…”

Section: A1 Plasmaelastic Bendingmentioning

confidence: 99%

How Lasers Exploit Photoacoustic and PhotoelectricPhenomena to Inject Signals into MEMS Microphones

Cyr,

Sumaria,

Long

et al. 2024

Preprint

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An amplitude-modulated laser can be used to generate false, yet coherent acoustic signals on the outputs of MEMS microphones. While this vulnerability has ramifications on the security of cyber-physical systems that trust these microphones, the physical explanation of this effect remained a mystery. Without an understanding of the physical phenomena contributing to this signal injection, it is difficult to design effective and reliable defenses. In this work, we show the degree to which the mechanisms of thermoelastic bending, thermal diffusion, and photocurrent generation are used to inject signals into MEMS microphones. We provide models for each of these mechanisms, develop a procedure to empirically determine their relative contributions, and highlight the effects on eight commercial MEMS microphones. We accomplish this with a precise setup to isolate each mechanism using several laser wavelengths and a vacuum chamber. The results indicate that the injected signal on the microphone is dependent on the wavelength of the incoming light, where long wavelengths (such as a 904~nm infrared laser) exploit photoelectric effects on the ASIC, while short wavelengths (such as a 450~nm blue laser) exploit photoacoustic effects on the diaphragm and surrounding air. This understanding leads to recommendations for future laser-resistant microphone designs with improvements to glob top application, reducing the material asymmetries within the MEMS structure, and adding simple light or temperature sensors for injection detection. Based on the fundamental causality, we also suggest potential vulnerabilities within other sensors with similar characteristics to MEMS microphones, such as conventional microphones, ultrasonic sensors, and inertial sensors.

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The Influence of Excess Free Carriers as Heat Carriers on the n-Type Silicon Thermoelastic Photoacoustic Responses Explained by Electro-Acoustic Analogies

Markushev,

Branković,

Aleksić

et al. 2024

Int J Thermophys

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Enhancement of the thermoelastic component of the photoacoustic signal of silicon membranes coated with a thin TiO2 film

Cited by 11 publications

References 18 publications

Thermal Fractional Diffusion: Experimental Evidence from the Discrepancies in the Amplitude and Phase in Photothermal Technique

Thermal Fractional Diffusion: Experimental Evidence from the Discrepancies in the Amplitude and Phase in Photothermal Technique

How Lasers Exploit Photoacoustic and PhotoelectricPhenomena to Inject Signals into MEMS Microphones

The Influence of Excess Free Carriers as Heat Carriers on the n-Type Silicon Thermoelastic Photoacoustic Responses Explained by Electro-Acoustic Analogies

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