Extremely Compliant Yet Tough Hydrogel Systems as Ultrasound Transmission Agents
This technology has applications as an ultrasound transmission agent.
Researchers
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compliant yet tough hydrogel systems as ultrasound transmission agents
United States of America | Granted | 9,878,506
Figures
Fig. 1. Schematics of the design principle for tough and resilient hydrogels: (a) Resilience material requires low mechanical dissipation under deformation, indicated by small hysteresis in the stress–strain curve. (b) Tough material requires high dissipation during crack propagation in it, indicated by large hysteresis in the stress–strain curve. (c) Resilient and tough hydrogel can be designed with delayed dissipation. The hydrogel is resilient
Fig. 2. Schematics of a practical method to implement the design principle by controlling damage of interpenetrating-network hydrogels. The pre-stretch will damage the short-chain network in the hydrogels to controlled degrees. If the pre-stretched hydrogel is further deformed within the range of λR, it will be resilient. If the sequent deformation is beyond the range of λR, more chains in the short-chain network can be fractured to further dissi
Fig. 3. Experimental validation of the design principle and method with PAAm–alginate hydrogel. (a) Schematics of the pre-stretch and further deformation of the hydrogel sample; (b) Stress vs. stretch curves of the sample pre-stretched to λR=5 and further stretched to λmax=5 and 8, respectively. (c) Stress vs. stretch curves of the sample with λR=5 stretched to λmax=2, 3 and 4, at different rates.
Technology
Resilience and toughness are intrinsically contradictory properties for a material -- high resilience requires low mechanical dissipation while high toughness requires high mechanical dissipation when undergoing material deformation. This invention pertains to a new innovative method and material system to design both extremely tough and resilient hydrogels. The extraordinary properties of the new hydrogels are achieved through the mechanism of delayed stiffening and mechanical dissipation. The hydrogels can be formed and printed into various shapes with different dimensions. One particular application of the new gel system is as ultrasound transmission agents. This extremely soft and tough hydrogel can conform to varying contours of both the human body and the ultrasound probe.
Problem Addressed
Typically, liquid gel is used in ultrasound procedures to improve the transmission of the ultrasound signals from the transducer to the body. However, conventional liquid hydrogels dry quickly or drip off the patient’s skin quickly. This new compliant and tough hydrogel conforms to the contours of the human body and remains effective for at least 30 minutes.
Advantages
- Low shear modulus, can be conformably attached to different regions of human body and wrap ultrasound probes of complex shapes
- Extremely robust
- Produces high quality ultrasound images comparable to that of conventional liquid hydrogels without dripping or drying up
Related Technologies
This case is related to MIT technology: #19677
Publications
Lin, S., Zhou, Y., and Zhao, X. (2014). Designing extremely resilient and tough hydrogels via delayed dissipation. Extreme Mechanics Letters, 1, 70-75. ISSN 2352-4316. doi: 10.1016/j.eml.2014.11.002.
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