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TED Talks Daily

Why your blood should flow like ketchup | Sean Farrington

with Sean Farrington

Published November 7, 2025
View Show Notes

About This Episode

Host Elise Hu introduces a TEDx talk by chemical engineer Sean Farrington about rheology, the study of how materials flow and deform, and why it matters far beyond consumer products. Farrington explains how rheology is used to control the texture and performance of everyday items like peanut butter, shampoo, and ketchup, then connects these principles to the non-Newtonian, shear-thinning behavior of blood and its link to cardiovascular disease. He argues that measuring blood's viscosity more routinely could improve early detection of heart conditions, describes his work on a portable microfluidic device to make such measurements accessible, and calls for greater awareness and collaboration between engineers, physicians, and the public.

Topics Covered

Rheology Non-Newtonian fluids Blood viscosity Cardiovascular disease Healthcare system Science communication Chemical engineering Microfluidic devices

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Quick Takeaways

  • Rheology, the study of how materials flow and deform, underpins the design and performance of many everyday products, from peanut butter to shampoo and ketchup.
  • Many consumer materials, including ketchup and blood, are non-Newtonian fluids whose viscosity changes under different flow conditions.
  • Blood behaves as a shear-thinning fluid, and if its viscosity is too high it can increase the risk of clots or aneurysms, making viscosity a potentially valuable diagnostic metric.
  • Despite over a century of study and evidence linking blood viscosity to cardiovascular disease, rheological measurements of blood are not yet widely used in routine medical diagnostics.
  • Sean Farrington is working on a small, cheap, portable microfluidic chip designed to capture the same rheological information that currently requires a large, expensive laboratory machine.
  • He emphasizes that engineers have a responsibility because when they "mess up, people die," highlighting the life-or-death stakes of applying engineering in medicine.
  • Farrington calls for greater public awareness of blood rheological measurements, likening their potential impact to that of blood pressure monitoring over the last 300 years.
  • He urges members of the medical community to explore how this science could augment patient care and help address major modern cardiovascular health challenges.

Podcast Notes

Podcast introduction and episode setup

Host introduction and show framing

Elise Hu identifies herself as the host of TED Talks Daily[2:07]
She explains that the show brings listeners new ideas to spark curiosity every day[2:13]

Introducing the topic of rheology

Rheology is described as the branch of physics that studies the deformation and flow of materials, both solids and liquids[2:18]
Elise notes that rheology is one of the lesser-known scientific fields of study[2:26]
She introduces Sean Farrington as a chemical engineer[2:28]
According to Elise, Sean believes rheology has the potential to completely transform how we understand and diagnose cardiovascular disease[2:33]

What the talk will cover

Elise previews that Sean will explain why rheology is so powerful[2:39]
She says he will argue that engineers and medical professionals need to work together to integrate this emerging science into routine care[2:45]

Sean Farrington's path to engineering and rheology

Childhood inspiration from his uncle

Sean recalls that when he was a kid, his uncle would tell him great stories about his aerospace engineering career[2:58]
His uncle described the machinery and designs he had built throughout his life[3:04]
The uncle said he had picked the perfect career because of all the cool things he was able to build[3:09]
Sean shares a specific story of his uncle working in the nose cone of an Apollo rocket, fixing a sensitive piece of equipment just days before launch[3:16]
Sean says he was enamored by these stories and daydreamed about the innovative technology he could build[3:30]
These experiences inspired him to become an engineer as well[3:36]

Realizing the responsibility of engineering

Sean notes that since going down the engineering path, he has learned there is more to engineering than the amazing things that get built[3:39]
He emphasizes that there is also a vital responsibility in engineering work, sometimes with the ability to save human life[3:47]
He distills the stakes: when engineers mess up, people die[3:54]
Sean mentions that his PhD advisor warned him about this responsibility when Sean started working with him four years ago[3:59]

Choosing chemical engineering and discovering rheology

Sean says that when he decided to follow the path of chemical engineering, he never imagined he would do his PhD in rheology[4:05]
He explains that rheology interested him enough that he chose to spend a few years of his life understanding it[4:17]

Explaining rheology through everyday materials

Definition and purpose of rheology

Sean defines rheology as the study of flow and deformation of matter[4:23]
He says rheology is mainly a method to measure the viscosity or thickness of a material so that it works for its intended function[4:28]
Rheology is best used for materials that are neither purely liquid nor purely solid but some combination of both[4:39]

Rheology in consumer products

Sean notes that the concepts of rheology are easiest to understand by comparing different products[4:49]
He says rheology is essential to almost every consumer product on the market[4:58]
• Examples include lotion that evenly coats your hands
• Another example is motor oil that lubricates at all operating temperatures
• He also mentions cement that must not harden before making it to the job site
He notes there are many other examples across many industries where rheology matters[5:17]
Sean invites the audience over to the rheology lab so he can demonstrate the concepts[5:21]

Peanut butter example

Sean remarks that everybody has their favorite peanut butter, unless they are allergic[5:28]
He contrasts a peanut butter that will stick to the bread with one that cannot support itself and slides right off[5:41]
These differences in behavior illustrate differing rheological properties between products[4:58]

Shampoo example

Sean moves to shampoo and says its purpose is to squeeze from the bottle and sit on your hand so you can measure out a drop to clean your hair[5:47]
He describes what happens when shampoo gets low and someone fills the bottle with water to save the last drop[6:05]
After being diluted with water, the shampoo no longer stays in the palm of the hand, which ruins one of its core functions[6:11]

Ketchup experiment

Sean calls ketchup his favorite example[6:19]
He notes that ketchup shows a huge difference in texture between popular brands[6:28]
He sets up an experiment with one ketchup in each beaker[6:36]
He says that when the beakers are flipped, the audience should watch closely to see which ketchup drains faster[6:41]
He observes that one ketchup is clearly much thicker than the other[6:51]
Sean notes that the thicker ketchup happens to be his personal preference[6:54]

Non-Newtonian fluids and rheological measurement

Sean explains that all the materials in his demonstration belong to a class of materials called non-Newtonian fluids[7:04]
He says rheology is used to measure the different flow properties of each of these materials[7:06]
These measurements allow materials to be made reproducibly and with the most desired texture for their application[7:17]
Sean suggests that by this point the audience might see the value of rheology for product manufacturing[7:22]

Applying rheology to blood and cardiovascular disease

Why your blood should flow like ketchup

Sean poses the question: why should your blood flow like ketchup?[7:29]
He says one application of rheology that most interests him is medical diagnostics[7:40]
He explains that our blood does not flow like water, contrary to what people might imagine[7:43]
Instead, blood flows a bit closer to ketchup in its behavior[7:48]
He states that blood is a non-Newtonian fluid, like the materials in his demonstration[7:52]
Specifically, Sean describes blood as a shear-thinning fluid[7:59]
He says this shear-thinning behavior is necessary for healthy blood flow[8:04]
If blood's viscosity is too high, there is a higher chance of developing something like a clot or potentially an aneurysm[8:10]
Measuring viscosity and related information could give physicians another method to detect cardiovascular disease[8:22]

Underuse of rheology in medicine

Sean notes that despite this potential, rheology is not being used widely in medical diagnostics[8:28]
He characterizes rheology as a niche technical engineering field that is largely unknown to the public[8:28]

Prevalence and impact of heart disease

Sean says he bets everyone can think of at least one person in their life who has or had a heart condition[8:36]
He cites studies showing that up to 46% of people over age 40 have some form of coronary atherosclerosis[8:51]
• He defines coronary atherosclerosis as a chronic condition where plaque builds up in arteries and narrows them, reducing blood flow
Sean states that one quarter of deaths in the United States are caused by heart disease[9:04]
He points out that a major challenge in these diseases is detecting them early enough for medication and treatment to take effect[9:13]

Blood pressure as a long-standing diagnostic tool

Sean notes that blood pressure is a metric commonly used by physicians to inform decisions about medications and treatment of cardiovascular disease[9:20]
He says blood pressure monitoring has been in use for over 300 years[9:33]
He asks the audience to imagine the past 300 years if physicians had not known about blood pressure monitoring[9:45]
Without blood pressure monitoring, there would have been countless unnecessary suffering[9:45]
Sean argues that this is the stage that blood rheological measurement is currently at, though the transcript refers to it as blood radiology[9:52]
He notes that blood's viscosity has been studied for over 100 years[9:58]
He says specialists (transcribed as blood radiologists) have shown significant evidence correlating blood viscosity to cardiovascular disease[10:00]
Despite this evidence, blood viscosity measurement is still not widely used as a diagnostic tool[10:07]
Sean argues that spreading awareness about rheology is necessary so that it becomes as commonly known as blood pressure monitoring[10:15]

Research, technology development, and call to action

Collaboration between physicians and engineers

Sean describes blood-related rheological work as an area where physicians can work together with engineers[10:23]
He says this collaboration can proactively create solutions that put rheological knowledge into medical practice[10:28]

Sean's PhD work on simplifying measurements

Sean explains that some of his work as a PhD student is to help simplify the rheological measurement[10:38]
He says that while he is studying the radiology of blood and its use for cardiovascular disease diagnosis, he is also building a small microfluidic chip[10:48]
His goal is to measure the same rheological information on a small, cheap, portable device that is currently obtained on a bulky, stationary, half-a-million-dollar machine[11:03]
He argues this could simplify the rheological measurement and make it more accessible for many doctors[11:11]
Sean notes that some physicians have begun to use blood-related rheological information to augment their patient care[11:17]
He says these physicians have seen positive results so far[11:19]
He suggests that, like the blood pressure monitor, everyone will be better off when the public has greater awareness of this technology[11:22]

Appeal to the public and medical community

Sean explains that this is why he is asking the audience to have a conversation with someone in their life about this science[11:39]
He directly addresses people in the medical community, asking them to take a closer look at blood-related rheological science (transcribed as blood radiology)[11:47]
He urges them to dive into this science and see how they might use it in their field[11:52]
Sean asserts that there is a lot of valuable information in blood-related rheological measurement that tells us about our health[11:59]
He says that if we can get over the obscurity of this field, we might be able to help solve some of our most pressing modern medical issues[12:09]
He concludes that if we just spread a little awareness, we could save lives[12:13]

Outro and production credits

Context about the talk and TED curation

Elise identifies the speaker as Sean Farrington and notes that the talk was given at TEDx Wilmington in Delaware, USA in 2025[12:17]
She mentions that listeners curious about TED's curation can find out more at TED.com slash curation guidelines[12:33]

Show credits and closing

Elise states that TED Talks Daily is part of the TED Audio Collective[12:38]
She notes that the talk was fact-checked by the TED Research Team[12:41]
She lists members of the production and editing team: Martha Estefanos, Oliver Friedman, Brian Green, Lucy Little, and Tansika Sangmarnivong[12:49]
She says the episode was mixed by Christopher Fasey-Bogan[12:52]
She mentions additional support from Emma Taubner and Daniela Balarezo[12:54]
Elise signs off by saying she will be back tomorrow with a fresh idea and thanks listeners for listening[12:59]

Lessons Learned

Actionable insights and wisdom you can apply to your business, career, and personal life.

1

Technical fields that seem niche or obscure, like rheology, can hold insights that fundamentally improve how we diagnose and treat major health problems when they are connected to real-world applications.

Reflection Questions:

  • • What specialized knowledge or technical expertise do I have access to that might be underused outside its niche community?
  • • How could I better connect a "niche" concept I know about to a pressing real-world problem in my work or life?
  • • What is one concrete step I could take this month to translate a specialized idea into something more understandable and useful for non-experts around me?
2

Choosing the right things to measure-like blood viscosity or blood pressure-can unlock earlier detection of problems and lead to better decisions and outcomes over time.

Reflection Questions:

  • • In my current projects or goals, what key metric might I be overlooking that would give me a clearer picture of risks and progress?
  • • How could systematically tracking a single, well-chosen indicator change the way I make decisions in my work or personal life?
  • • What is one important domain (health, finances, relationships, career) where I should define and start monitoring a more meaningful metric this week?
3

Engineers and other technical professionals carry a real responsibility because their designs and decisions can directly affect human safety and wellbeing.

Reflection Questions:

  • • Where in my work do the choices I make have downstream consequences for other people's wellbeing, even if those consequences are indirect?
  • • How might my approach change if I regularly asked myself who could be helped or harmed by the systems, products, or processes I contribute to?
  • • What is one practice I can adopt (such as peer review, testing, or seeking feedback from affected users) to better honor the responsibility inherent in my role?
4

Simplifying and miniaturizing complex tools-like turning a half-a-million-dollar lab machine into a small, portable microfluidic chip-can dramatically expand access and impact.

Reflection Questions:

  • • Which tools, processes, or workflows in my environment are currently too complex or expensive for most people who could benefit from them?
  • • How could I redesign or streamline one of these tools or processes so that it becomes easier, cheaper, or more portable without losing its essential value?
  • • What is one concrete experiment I could run in the next few weeks to test a simpler version of something that is currently overcomplicated?
5

Raising awareness and fostering collaboration across disciplines, such as between engineers and physicians, is often necessary to move promising ideas from research into everyday practice.

Reflection Questions:

  • • Where have I seen good ideas stall because the right people or disciplines were not in conversation with each other?
  • • How could I intentionally connect different stakeholders-technical, operational, or user-focused-to accelerate the adoption of a useful idea I care about?
  • • What is one relationship or cross-disciplinary conversation I could initiate this month that might help bridge a gap between research and real-world application?

Episode Summary - Notes by Rowan

Why your blood should flow like ketchup | Sean Farrington
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