研究

空间的泡沫

Experiment on International Space Station aims to improve cancer detection

罗腾飞 had certain hypotheses about what would happen during his scientific experiment, conducted in June aboard the International Space Station, to form water vapor bubbles in an environment without gravity.

一名男子在装满实验室玻璃器皿和设备的玻璃空间前摆姿势拍照.
罗腾飞教授在他的实验室在Fitzpatrick Hall.

他的目标是设计材料表面,使更大的气泡附着在表面上,而不是像在地球上那样漂浮并分离. 在他的第一次超越这个世界的经历中,他得到的东西比他预期的要少,也比他预期的要多.

“我发现有趣的是,气泡确实会分离,”罗说 of the near real-time videos beamed back from space. “它们确实比我们在地球上看到的更大. 那里没有重力,这意味着我们可能看到了我们想看到的物理现象. There is a competition between other factors that led them to detach.”

与预期, 罗说, the bubbles grew slowly but suddenly detached at once while still at different sizes.

如果我之前的假设是正确的, the bubbles will detach when they grow to a certain size,”他说. “但情况似乎并非如此,所以我们不知道发生了什么,我们需要找出原因.”

A SpaceX Falcon 9 rocket launched from Cape Canaveral on June 3, 2021. 两天后,它与国际空间站连接,宇航员在第二天插入实验. It returned to Earth on another resupply flight about a month later.

A screenshot of a live stream of the SpaceX Falcon 9 rocket at launch.

2021年6月3日:SpaceX猎鹰9号火箭 & Cargo Dragon spacecraft launch research and supplies to ISS.

罗博士最终希望利用气泡来集中血液样本中的生物标记物,这样癌症就能尽早被发现和治疗. 为了到达那里,教授在 航空航天与机械工程系 需要更好地理解气泡动力学中相互竞争的物理力量.

在这个科学受到人们攻击的时代,人们对从口罩到疫苗的一切建议都持怀疑态度, Luo is excited that his experiment did not follow his expectations.

相反,它打开了新的调查之门.

Besides unexpected results, there was a glitch in the experiment. 里面的摄像头是全自动的, 在捕捉到第一个气泡的视频后,独立的实验箱未能移动到三个不同的吹泡面.

Still, Luo estimates he accomplished about 70 percent of his goals.

“我们得到了一些有价值的信息,”罗说. “我认为这是一个好的开始. 我们相信,我们从这次尝试中学到的东西,可能会引导我们在生物检测方面设计出更好的东西.”

竞争的力量

罗出生于中国,2005年来到美国密歇根州立大学攻读博士学位. 在麻省理工学院做博士后之后, 他在亚虎体育找到了一份工作,开始了一个研究分子水平能量和质量运输的实验室.

改名为 MONSTER (Molecular/Nano-Scale Transport and Energy 研究) Lab in 2019, Luo’s group hopes to improve diagnostic capabilities for life-threatening diseases, 包括某些癌症, 通过更好地理解泡沫的形成, grow and detach from solid surfaces with different nanoscale features. 癌细胞是否可以在低浓度时通过气泡收集, then this method could increase sensitivity and improve early cancer detection.

Two people wearing lab coats and black goggles work with lazers on a table in a dark lab.
Professor 罗腾飞 works in his lab with graduate student Qiushi Zhang.

在2020年发表的一项研究中 先进材料界面, 罗成功地利用激光加热在含有生物分子的溶液中产生气泡. 研究人员发现,他们可以将这些生物分子吸引到气泡上,并将其沉积在气泡表面, 创造了一个“高度集中的岛屿”.” The National Science Foundation provided funding for biosensing research.

“We are proposing to use this bubble method to concentrate when we collect, 例如, 血液或唾液样本,”罗说. “我们希望将生物分子集中到一个小的位置,这样我们就有更高的生物标志物密度,从而更容易检测到它们.”

生物标记物需要一段时间才能到达气泡表面,这种现象被称为Marangoni流, so the bigger the bubble and the longer it can be maintained without detaching, 更好的. The biomarkers then quickly drain to the base of the bubble and are deposited there, 它们在哪里可以被测量.

Video of laser forming bubble in 罗腾飞’s lab on campus.
Video of bubble formation in the 空间探戈 CubeLab on the ISS.

Several competing factors can influence bubble dynamics: gravity, which affects the buoyancy of a bubble; capillary force, which is at the interface of the bubble and a solid surface; and the minimization of surface tension due to the bubble trying to be spherical in the liquid. Luo’s experiment aboard the ISS tested how bubbles behave in the absence of gravity.

“The capillary force pins the bubble on the surface,”罗说. “But the bubble wants to complete its perfect spherical shape. And then, under gravity you have the surface tension and buoyancy working together. 我们不能将这些力解耦. 但在国际空间站上,我们能够将它们解耦. 这样我们就能更好地理解这些不同因素是如何影响泡沫动态的.”

罗说,在国际空间站的实验中,他的气泡意外分离,需要进一步研究. That will include detailed analysis of high-resolution videos and terrestrial experiments.

“我们想找出主导泡沫脱离的关键机制,”罗说. 如果毛细管力是一个, then that would give us opportunity to tune the surface condition, 这样泡沫就会变大, and the larger the bubble we get the more sensitive our biosensors can get.”

发射到太空

Luo has been working toward the experiment on the ISS since about 2015. 他的团队意识到,可以人工创造的零重力空间不会持续足够长的时间来完成他的实验.

“作为亚虎体育的毕业生, 我想看到亚虎体育平台在太空研究方面真正取得进展,带来各种好处, 尤其是在地球上.” 乔纳森·沃尔克

Around the same time, Jonathan Volk, a 亚虎体育平台 engineering alumnus working at the 空间科学发展中心(CASIS) 来到亚虎体育平台是为了促进国际空间站的科学工作. Volk set up a meeting with former dean Peter Kilpatrick and 马克McCready,现任主席 化学和生物分子工程,以及几个感兴趣的教员.

“作为亚虎体育的毕业生, 我想看到亚虎体育平台在太空研究方面真正取得进展,带来各种好处, 尤其是在地球上,”人民说, 他现在是一家名为“太空商业事务”的咨询公司的商业化战略总监, 是什么推动了太空的科学和商业化. “The experiment Tengfei wanted to propose has great terrestrial applications in health care, 观察纳米粒子, 还有水的净化.”

CASIS focuses on space research with terrestrial applications, while 更好的-known NASA focuses on research and exploration affecting space. Volk举了过去CASIS项目的几个例子:宝洁公司提高了其清洁产品的保质期, Delta researching droplet formulation to use less water in showers, and Goodyear experimenting in silica to make tires more environmentally friendly.

Luo received funding from CASIS and began work on the ISS project in 2018, 但遇到了一些延误, 包括因COVID-19大流行而推迟. 的实验, 他需要一种设备,可以产生一个气泡,并记录视觉效果和气泡行为的读数,而不需要使用激光或生物分子——这将花费更多,并造成安全隐患.

An astronaut turns on the power for the 空间探戈 CubeLab on the ISS.

ND实验完成后,一名宇航员在移走CubeLab前竖起大拇指.

“我们正在做基础研究,”罗说. “我们设计实验, but somebody needs to convert that idea into a fully automated, flight-ready装置.”

罗说,第一个实施伙伴已经完成了一半的项目,还需要100万美元才能完成. 于是他找了个新搭档 空间探戈, to build a container lab that can be inserted into a slot on the ISS and run on its own. 空间探戈 specializes in designing and building automated hardware for use in space.

实验装置装在一个小立方体里, 叫做CubeLab, 哪个有四个液体室, 加热表面的热能力, and four different copper surfaces with different scales of structures, 或工程表面, 从100纳米到几微米.

“我们认为,可能存在一种结构尺寸,可以提供最佳的钉扎力,使其生长得更大, 更稳定的泡沫,”他说.

一个穿着白色实验服的人拿着一个立方体. A monogram sticker with College of Engineering on the front of the cube.
The inside of the cube equipped with four fluid compartments, 加热表面的热能力, and four different copper surfaces with different scales of structures, 或工程表面.
Engineers at 空间探戈 built the CubeLab to run 罗腾飞’s experiment. The automated CubeLab contains four fluid compartments with different engineered surfaces. 照片由空间探戈提供.

The CubeLab experiments on each substrate only took a few minutes, 但他们必须重复几次, and there was a cooling time of several hours between each bubble heating. 总的运行时间大约是三周. 不幸的是, 一个相机故障阻止它移动到其他三个基板以记录视频进行比较. 罗和他的团队确实收到了温度和压力读数以及加热功率值, 此外,高分辨率视频的第一个位置具有最小的纳米结构表面.

“我们将在未来两周深入研究这些视频,看看我们能发现什么有趣的东西,罗在8月份说. “我们从一个表面获得的数据已经阐明了重力对气泡动力学的重要性.”

罗并没有阻止. He said the experience has been unique and the results interesting. 他明白,科学实验本身就包含风险,目的是推动人类知识的边界. 空间探戈 has indicated it plans to send the CubeLab to the ISS again. In the meantime, Luo may devise a workaround here on Earth.

“我们可以根据某些假设开发一些计算模型,并使用国际空间站的实验结果来验证这些模型,”罗说. “然后我们使用这些模型来预测我们无法捕捉到的其他表面会发生什么.”