Dr Yukkee Cheung, biomedical engineer

5 March 2018

Cardiio is a digital health company developing algorithms to allow smartphones and wearables technology to monitor human wellbeing. Cardiio was co-founded by Dr Yukkee Cheung Poh (Croucher Scholarship 2006), an electrical engineer who turned to biomedical engineering because of her passion for advancing healthcare and medicine.

Cardiio’s first product, Cardiio Heart Rate Monitor, is a popular lifestyle fitness app with millions of downloads worldwide. A second product, Cardiio Rhythm, an AI-based technology to identify irregular heartbeats for stroke prevention, has recently completed multiple clinical validation studies.

Cheung studied electrical engineering at Cornell University as an undergraduate. “Being trained as an electrical engineer gives me invaluable skills – programming, making computer chips, and circuit design. But what excites me most is to see application of my work in the biomedical area,” Cheung said.

Cheung enrolled in the PhD program in biomedical engineering at Columbia University, where she met Professor Samuel K Sia, an expert on point-of-care diagnostics for developing countries and lower income communities. Inspired by Sia’s expertise, Cheung worked on a handheld HIV diagnostic device that was field-tested in Rwanda. She also ventured into tissue engineering using techniques she learned from fabricating computer chips.

Following this Cheung became a postdoctoral fellow at Harvard Medical School under Professor Jeffrey Karp, an expert in biomaterials. This was when she first laid out the plan of setting up Cardiio.

How Cardiio works

In 2012, Chueng husband, Dr Ming-Zher Poh, then a PhD student at MIT Media Lab, invented a smart mirror that measured the body’s vital signs using light. This technology was broad in application, and could be integrated into any device that has a camera.

“It was exciting, it took me back to my PhD days, it was like a cheap point-of-care diagnostic with high potential for hard to reach regions, and that made up our mind to start a company,” said Cheung.

San Francisco based health incubator Rock Health provided the initial grant to kick-start Cardiio, but the team eventually relocated to Boston, where they were to carry out clinical trials.

Cardiio Heart Rate Monitor employs the same physics as the medical mirror does. Every time your heart beats, blood flow to your face and fingers increases. Since blood absorbs light, this causes more light to be absorbed. Alternatively, in between the beats when the heart is resting, less light is absorbed. Cameras can detect tiny changes in reflected light from your finger or face. The Cardiio team developed this app to leverage smartphone cameras to calculate the heart rate.

There are two ways to find out the heart rate, users can either chose to put their finger over the lens, let LED shine through the finger and measure blood volume pulse, or look into the camera that will capture blood flow from the face and learn how fast the heart is beating at any given time.

The Cardiio app also keeps track of an individual’s daily workout as it comes with a seven minute pre-set exercise program. However, it is not to be used for medical purposes and cannot predict any heart conditions.

“Understanding physiology and machine learning are integral to the work we do at Cardiio, and for me it’s just satisfying to be able to build on what I learnt in electrical and biomedical engineering in my day-to-day work.” added Cheung.

She went on to say, “engineers today are working across different domains and this interdisciplinary approach is needed to tackle complex problems in healthcare. Our interconnectivity and mutual exchange of knowledge have helped push us further, faster.”

Cardiio Rhythm

Cheung says her company wants to make a medical impact, and not just build a lifestyle fitness app. The first step was to distribute the app to the mass market, and once a sizeable user base was established, the team were able to use the data to detect underlying diseases from pulse waveforms, including Atrial Fibrillation (AF).

AF is a heart rhythm disorder characterised by irregular heartbeat, which is a leading cause of strokes and also associated with dementia and heart failure. Most AF-related strokes are preventable if diagnosed on time, but more often than not AF goes undetected as it has few symptoms.

“Many people die from stroke associated with atrial fibrillation. The good news is if we can catch atrial fibrillation on time, we can put patients on medication, decreasing their chance of having a stroke by up to 80%,” explained Poh.

The second product Cardiio Rhythm is a technology developed to detect AF from pulse waveforms collected using a smartphone camera or optical sensors in wearable devices. Cardiio Rhythm employs machine learning algorithms, analyses pulse waveform data, and identifies the AF pattern from other heart rhythms. It has been validated in multiple clinical trials in the US and Hong Kong, including two studies in collaboration with Dr Siu Chung Wah (Croucher Fellowship 2005), a cardiology professor of the University of Hong Kong, as well as Dr Bryan Yan, an associate professor at the Chinese University of Hong Kong.

Artificial tissue

Before Cardiio, Cheung was involved in tissue fabrication research and her dissertation presented a novel fabrication technique for constructing spatially complex structures made of soft tissues, “we were able to fabricate tissue in such a way that you can dictate the geometry, positions and biomaterials in which different cell types dwell, but it’s still a long way from creating complex, functional artificial tissues,” explained Chueng, adding, “such tissue also requires making sure other functions like blood flow and neuron connectivity are in place.”

While the more complicated soft tissues are harder to regenerate, fabrication of cartilage tissue has found significant application in medical science, replacing damaged tissue between joints.

Next steps

Moving ahead, while Cardiio Rhythm is getting ready to market, the team continues to diagnose other heart conditions using pulse waveform, which contains important information about a person’s wellbeing.

Cheung concludes, “we are not stopping at atrial fibrillation. We’d like to see if we can detect high blood pressure, diabetes, and more.”



Dr Yukkee Cheung is Co-Founder and Chief Technology Officer at Cardiio, Inc. She earned her MS and PhD in Biomedical Engineering from Columbia University and later joined Harvard Medical School as a postdoctoral fellow. Dr Cheung obtained her BS degree in Electrical Computer Engineering from Cornell University. In 2006, Dr Cheung  was awarded Croucher Scholarship for PhD study at Columbia University. 


To view Dr Cheung’s Croucher profile, please click here.