Real-time characterization of hydrogel viscoelastic properties and sol-gel phase transitions using cantilever sensors

Haring, Alexander P.; Singh, Manjot; Koh, Miharu; Cesewski, Ellen; Dillard, David A.; Kong, Zhenyu; Johnson, Blake N.

doi:10.1122/8.0000009

Cited by 12 publications

(24 citation statements)

References 62 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%

“…In our recent studies, we showed that the phase angle change of PEMC sensors enables real-time monitoring of hydrogel viscoelastic moduli and that the storage moduli of various hydrogels correlated with that obtained using DMA. , Thus, prior to discussion of the closed-loop controlled photopolymerization process and the properties of associated hydrogels, we first examined the effect of hydrogel crosslinking on the frequency response of a PEMC sensor for two hydrogels, PEGDMA and PNIPAm. PEGDMA was selected given its wide use in tissue engineering applications and widely available structure and material property characterization data. ,, PNIPAm was selected given its use in stimuli-responsive hydrogel systems, such as alginate-PNIPAm. − As shown in Figure a,b, photopolymerization of PEGDMA and PNIPAm hydrogels is associated with a decrease in both the quality factor and phase angle of the second mode of the PEMC sensor ( f air = 86 ± 0.16 kHz).…”

Section: Resultsmentioning

confidence: 99%

“…Figure a,b shows that material photopolymerization (crosslinking) is associated with a significant change in the phase angle and quality factor of the resonant mode. The second mode was selected based on its use in previous studies for rheological sensing applications. ,, …”

Section: Resultsmentioning

confidence: 99%

Section: Monitoring Of Hydrogel Photopolymerizationmentioning

confidence: 99%

“…However, differences in overshoot among the controllers as characterized by sensor data were not statistically significant. While sensor phase angle data correlate with the hydrogel storage modulus for various material systems 34 (also see Figure 3e,f), it provides an indirect measure of the low-frequency storage modulus, which is utilized as a performance metric across various applications. As shown in Figure 6a, the bang-bang and rate-based bangbang controllers with the lowest tuning parameter value resulted in the least amount of overshoot for the PEGDMA system.…”

Section: Monitoring Of Hydrogel Photopolymerizationmentioning

confidence: 99%

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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%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Monitoring Of Hydrogel Photopolymerizationmentioning

confidence: 99%

Section: Monitoring Of Hydrogel Photopolymerizationmentioning

confidence: 99%

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Closed-Loop Controlled Photopolymerization of Hydrogels

Singh

Zhang

Bethel

et al. 2021

ACS Appl. Mater. Interfaces

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Hydrogels

Ray

2022

Kirk-Othmer Encyclopedia of Chemical Technology

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Hydrogels are prepared by physical or chemical cross‐linking of water‐soluble polymers. Natural, semisynthetic, and synthetic polymers may be cross‐linked physically or by a cross‐linker to produce the network structure of a hydrogel. Because of cross‐linking these polymers are not soluble in water. However, hydrogels can absorb huge amount of water, resulting in significant swelling of their three‐dimensional network structure. The swelling of a responsive and smart hydrogel strongly depends on external stimuli such as pH, temperature, salt concentration, light, and magnetic and electric fields. Hydrogels are widely reported for various applications. In fact, in recent years the research on hydrogel has been found to increase at an exponential rate, with around 8000 publications in 2021. In this article, the origin, history, theoretical modeling, synthesis, properties, classifications, characterization, and new applications of hydrogels have been discussed in detail with the citation of references till 2021.

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