Dr. Seungwoo Lee, Co-Founder and CTO of Leesol: “Revolutionizing Sleep Through Science”

KAIST-trained engineer and 30-year medical device expert embarks on a new challenge

Dr. Seungwoo Lee, co-founder and CTO of Leesol, holds the Sleepisol Plus device in his hand.

Dr. Seungwoo Lee, CTO and co-founder of Leesol, is a pioneer who has led innovation in medical devices for decades. A KAIST graduate with a Ph.D. in Electrical Engineering, he previously helped establish Korea’s first-generation ultrasound medical device company Medison (now Samsung Medison) and later founded BioSoundLab, a smart hearing aid company. Today, he is focusing on a new challenge—designing the future of digital healthcare at Leesol, with “sleep” as the central theme of his third entrepreneurial journey.

We met with Dr. Lee to discuss Leesol’s current achievements, future vision, and philosophy behind its technology development.

Q. What kind of company is Leesol?

A: Leesol is an electroceutical healthcare startup founded in October 2017. The company develops wellness products such as the Sleepisol series—wearable devices designed to promote better sleep using electrical stimulation.

Leesol focuses on developing electroceutical solutions equipped with technologies that help relieve symptoms such as anxiety, depression, and stress, ultimately improving mental health and quality of life. Despite challenging market conditions during its early years, the company built strong trust both domestically and internationally, supported by the technological expertise of key personnel from Medison, one of Korea’s first medical device venture companies.

In 2021, Leesol’s technology received recognition when it won the Korea Invention Promotion Association President’s Award at the Korean Intellectual Property Office’s Intellectual Property Competition, as well as the Minister of SMEs and Startups Award at the K-Startup Grand Challenge.

Q. What are your representative products and technologies?

A: Our flagship product, Sleepisol, is a wearable sleep-inducing device that meets safety standards established by the U.S. Food and Drug Administration (FDA). Designed as a headband worn on the forehead, it allows anyone to use it easily and comfortably.

The device uses transcranial electrical stimulation (tES) technology, which applies microcurrents to stimulate specific areas of the brain to promote restful sleep.

Our upgraded model, Sleepisol Plus, enhances its brainwave entrainment function. It sends subtle electrical signals similar to the brainwave patterns associated with deep sleep or focused states. The device also features an algorithm that analyzes biometric signals in real time to create an optimal environment for sleep, effectively improving overall sleep quality.

Q. We heard that the motivation behind developing the product is quite personal.

A: Yes, the inspiration actually came from my wife. Because her work often requires overseas travel, she frequently experienced insomnia caused by jet lag and stress.

Seeing her struggle made me want to find a way to help. During that process, I realized that many people suffering from sleep disorders rely on medication or cannot find appropriate treatments. That realization motivated us to begin developing a technological solution.

At the time, numerous research papers suggested that electrical stimulation could produce various effects—such as improving concentration or alleviating stress and depression—depending on how it is applied. That gave us confidence that the technology had great potential.

Q. Could you share some recent achievements of the Sleepisol product?

A: Sleepisol recently won the Innovation Award in the Beauty & Personal Care category at CES 2025, the world’s largest consumer electronics exhibition held in the United States. This recognition highlighted both its technological innovation and design excellence on the global stage.

In addition, the product was selected as a finalist in the Medical & Health category at the 2024 IDEA Design Award, further validating its design and functionality internationally.

These awards demonstrate that Leesol’s products deliver innovative value not only in sleep improvement but also in mental wellness management and user experience, proving their competitiveness in the global market.

Q. Could you explain more about Leesol’s core technology?

A: Our core technology is tES (transcranial electrical stimulation). Leesol’s proprietary neurofeedback brainwave entrainment technology analyzes brainwave patterns and generates frequency vibrations tailored to what the brain needs—for example, to improve sleep or enhance concentration.

This approach overcomes the limitations of traditional electrical stimulation technologies, enabling both brain activation and brainwave synchronization.

By delivering a small amount of harmless microcurrent to the brain, the technology helps stimulate the secretion of serotonin—the “happiness hormone”—and melatonin, the hormone that regulates sleep. It also helps activate the body’s circadian rhythm, ultimately supporting better sleep quality.

Q. What was the biggest challenge during the development process?

A: Sleep disorders can arise from many different causes, so designing an algorithm capable of analyzing and responding to individual conditions took considerable time.

Another important factor was ensuring a comfortable and user-friendly design that enhances the overall user experience.

Q. How is the company progressing in terms of investment?

A: Recently, we secured KRW 4 billion (approximately USD 3 million) in Series A funding. In addition, Leesol was selected for the Deep Tech TIPS program, allowing us to secure up to KRW 1.7 billion in research and development funding.

These resources will play a crucial role in developing innovative products in the fields of sleep and mental health. Moving forward, Leesol will continue to develop advanced healthcare technologies to strengthen our competitiveness in the global market.

Q. What is Leesol’s future vision and goal?

A: Leesol’s vision is to provide solutions that benefit the brain and improve people’s lives through technological innovation.

The company name combines the Korean word “Ri” (benefit) with “solution.” In line with this philosophy, Leesol plans to develop solutions for early management of mild cognitive impairment using electrical stimulation and photic stimulation protocol technologies.

Our goal is to go beyond products and drive meaningful innovation in the healthcare industry while strengthening sustainable technological advancement and global competitiveness.

At the end of the interview, Dr. Lee added:

“In today’s fast-changing society, many people suffer from insomnia caused by irregular sleep patterns. Addressing this modern-day insomnia is the starting point of Leesol’s roadmap. As the holiday season approaches, we hope people can share health and happiness by gifting Sleepisol to their loved ones.”

Source: Korea IT Times (https://www.koreaittimes.com)