超声耦合剂聚丙烯酰胺水凝胶的配比优化工艺及其声学性能表征

Polyacrylamide hydrogel, an ultrasonic coupling agent: optimization process and acoustic performance characterization

背景:超声耦合剂是超声无损成像中必不可少的媒介,而超声探头使用寿命和更换频率主要由内部的耦合剂水凝胶材料选择决定。现有的凝胶耦合剂配方存在缺陷,使用一段时间后容易造成探头表面凹陷的现象,影响超声成像质量。目的:旨在优化凝胶耦合剂聚丙烯酰胺水凝胶的配方。方法:通过改变合成条件中丙烯酰胺单体浓度、单体与N,N-亚甲基双丙烯酰胺交联剂的比例等条件,优化聚丙烯酰胺水凝胶的放大合成工艺,探索影响其声学性质的因素,以期满足临床使用过程中的技术要求。结果与结论:当丙烯酰胺单体质量浓度调整到70 g/L,单体与N,N-亚甲基双丙烯酰胺交联剂质量比为7∶1时,聚丙烯酰胺水凝胶的状态最佳,所制得的聚丙烯酰胺溶胀率稳定、保水能力强、在受超声工作温度影响下体积变化小,并且其随超声频率变化的相对幅值也明显减小。结果说明,超声声源频率越高,聚丙烯酰胺水凝胶的声衰减系数越大;改变其单体浓度也会显著影响聚丙烯酰胺水凝胶的声学性质;利用这一点,可通过控制单体浓度配比,制得在最优浓度下表现出相对稳定声学性质且达到最优成像效果的耦合剂。

BACKGROUND:Ultrasonic coupling agent is indispensable in ultrasonic imaging.The service life and change frequency of the ultrasonic probe is determined by the internal coupling agent of the chosen hydrogel material.Due to defects in the existing gel-formula,after a period of time in use it can cause the surface depression of probes and thus influence the ultrasonic imaging quality.OBJECTIVE:To optimize the gel formula of the coupling agent.METHODS:The amplified synthesis process of polyacrylamide hydrogel was optimized by changing the ratio of monomer concentration to N,N-methylenebisacrylamide crosslinker in the synthesis conditions,and the factors influencing its acoustic properties were explored to meet the technical requirements in the clinical use process.RESULTS AND CONCLUSION:When the monomer concentration was set to 70 g/L and the mass ratio of monomer to crosslinker was 7:1,the polyacrylamide hydrogel was in the best state.The obtained polyacrylamide hydrogel had a stable swelling rate,had a strong ability to keep water and make the volume reduce under the influence of the operating temperature of ultrasound,and its relative amplitude changed less with the change of ultrasonic frequency.The sound attenuation coefficient of polyacrylamide hydrogel would be higher when the frequency of ultrasonic sound source was higher.The changes of monomer concentration would have significant impacts on the acoustic properties of polyacrylamide hydrogel.Therefore,by controlling the monomer concentration ratio,we can prepare the coupling agent that exhibits relatively stable acoustic properties at an optimum concentration and achieves an optimal imaging effect.