Persistence of bending and torsional modes in piezoelectric-excited millimeter-sized cantilever (PEMC) sensors in viscous liquids - 1 to 103 cP

Johnson, Blake N.; Mutharasan, Raj

doi:10.1063/1.3554677

Cited by 17 publications

(15 citation statements)

References 19 publications

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“…The second mode was selected based on its use in previous studies for rheological sensing applications. 33,34,39 As shown in Figure 3c,d, we next validated that the change in sensor response (phase angle and quality shift) associated with the exposure of the material to UV was driven by crosslinking within the material. The Raman spectra associated with the PEGDMA and PNIPAm precursor solutions after various exposure times are shown in Figure 3c,d, respectively.…”

Section: Monitoring Of Hydrogel Photopolymerizationsupporting

confidence: 56%

Closed-Loop Controlled Photopolymerization of Hydrogels

Singh

Zhang

Bethel

et al. 2021

ACS Appl. Mater. Interfaces

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Here, we present a closed-loop controlled photopolymerization process for fabrication of hydrogels with controlled storage moduli. Hydrogel crosslinking was associated with a significant change in the phase angle of a piezoelectric cantilever sensor and established the timescale of the photopolymerization process. The composition, structure, and mechanical properties of the fabricated hydrogels were characterized using Raman spectroscopy, scanning electron microscopy (SEM), and dynamic mechanical analysis (DMA). We found that the storage moduli of photocured poly(ethylene glycol) dimethacrylate (PEGDMA) and poly(Nisopropylacrylamide) (PNIPAm) hydrogels could be controlled using bang-bang and fuzzy logic controllers. Bang-bang controlled photopolymerization resulted in constant overshoot of the storage modulus setpoint for PEGDMA hydrogels, which was mitigated by setpoint correction and fuzzy logic control. SEM and DMA studies showed that the network structure and storage modulus of PEGDMA hydrogels were dependent on the cure time and temporal profile of UV exposure during photopolymerization. This work provides an advance in pulsed and continuous photopolymerization processes for hydrogel engineering based on closed-loop control that enables reproducible fabrication of hydrogels with controlled mechanical properties.

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Section: Monitoring Of Hydrogel Photopolymerizationsupporting

confidence: 56%

Closed-Loop Controlled Photopolymerization of Hydrogels

Singh

Zhang

Bethel

et al. 2021

ACS Appl. Mater. Interfaces

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“…1,2 Although cantilever sensor size widely varies depending on the intended application, [1][2][3] millimeter-scale cantilevers expressing highorder modes have shown promise in real-time sensing applications, [4][5][6][7][8][9][10][11][12][13][14][15][16] as they exhibit minimal damping in liquid. 14,17 Such a characteristic enables the continual monitoring of sensor properties throughout the measurement. 1 Thus, millimeter-scale cantilevers have been widely investigated for sensitive biosensing applications using resonant modes ranging from 10 kHz-1 MHz in complex liquid matrices including source waters, body fluids, and food matrices.…”

Section: Introductionmentioning

confidence: 99%

Acoustofluidic particle trapping, manipulation, and release using dynamic-mode cantilever sensors

Johnson

Mutharasan

2017

Analyst

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We show here that dynamic-mode cantilever sensors enable acoustofluidic fluid mixing and trapping of suspended particles as well as the rapid manipulation and release of trapped micro-particles via mode switching in liquid. Resonant modes of piezoelectric cantilever sensors over the 0 to 8 MHz frequency range are investigated. Sensor impedance response, flow visualization studies using dye and micro-particle tracers (100 μm diameter), and finite element simulations of cantilever modal mechanics and acoustic streaming show fluid mixing and particle trapping configurations depend on the resonant mode shape. We found trapped particles could be: (1) rapidly manipulated on millimeter length scales, and (2) released from the cantilever surface after trapping by switching between low- and high-order resonant modes (less than 250 kHz and greater than 1 MHz, respectively). Such results suggest a potentially promising future for dynamic-mode cantilevers in separations, pumping and mixing applications as well as acoustofluidic-enhanced sensing applications.

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“…To overcome such challenges, recent research has focused on the use of (a) alternative vibrational modes of microcantilevers in lieu of the fundamental transverse flexural mode or (b) efficient modes in structures of non-cantilever geometry. The former category includes investigations of higher modes of transverse flexure [2,[5][6][7][8], longitudinal modes [9][10][11], torsional modes [2,6,8,[12][13][14][15], and lateral (in-plane) flexural modes [10,13,[16][17][18][19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Lateral-Mode Vibration of Microcantilever-Based Sensors in Viscous Fluids Using Timoshenko Beam Theory

Schultz

Heinrich

Josse

et al. 2015

J. Microelectromech. Syst.

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To more accurately model microcantilever resonant behavior in liquids and to improve lateral-mode sensor performance, a new model is developed to incorporate viscous fluid effects and "Timoshenko beam" effects (shear deformation, rotatory inertia). The model is motivated by studies showing that the most promising geometries for lateral-mode sensing are those for which Timoshenko effects are most pronounced.Analytical solutions for beam response due to harmonic tip force and electrothermal loadings are expressed in terms of total and bending displacements, which correspond to laser and piezoresistive readouts, respectively. The influence of shear deformation, rotatory inertia, fluid properties, and actuation/detection schemes on resonant frequencies (fres) and quality factors (Q) are examined, showing that Timoshenko beam effects may reduce fres and Q by up to 40% and 23%, respectively, but are negligible for width-tolength ratios of 1/10 and lower. Comparisons with measurements (in water) indicate that the model predicts the qualitative data trends but underestimates the softening that occurs in stiffer specimens, indicating that support deformation becomes a factor. For thinner specimens the model estimates Q quite well, but exceeds the observed values for thicker specimens, showing that the Stokes resistance model employed should be extended to include pressure effects for these geometries.

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Persistence of bending and torsional modes in piezoelectric-excited millimeter-sized cantilever (PEMC) sensors in viscous liquids - 1 to 103 cP

Cited by 17 publications

References 19 publications

Closed-Loop Controlled Photopolymerization of Hydrogels

Closed-Loop Controlled Photopolymerization of Hydrogels

Acoustofluidic particle trapping, manipulation, and release using dynamic-mode cantilever sensors

Lateral-Mode Vibration of Microcantilever-Based Sensors in Viscous Fluids Using Timoshenko Beam Theory

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