Build the Medical Case Before Chasing the Consumer Market

Start With the Patient, Not the Specs

Long-term cardiac monitoring depends on patient compliance. Traditional Holter monitors — the bulky, six-lead devices patients wear for 24 to 48 hours — delivered accurate ECG data but were uncomfortable and conspicuous.

Meanwhile, cardiac arrhythmias often require 14 days or more of monitoring to detect, with detection rates climbing significantly the longer patients wear a device.

The problem wasn't just technical. It was behavioral. Patients complained that existing cardiac monitors were impossible to tolerate for extended periods — citing skin irritation, itchiness, and bulkiness.

“People just didn’t like that,” Young recalls. “When I wear a Holter, people start asking me what’s wrong with you.”

So before finalizing any design decisions, the team conducted more than 120 patient interviews — not just initial feedback sessions, but longitudinal follow-ups at six months and beyond. The interviews revealed hidden barriers like social stigma and day-to-day usability.

“We wanted to make sure patients wanted to wear it too,” Young explains.

Let Patients Shape the Design

Patient feedback drove two critical design choices that set the S-Patch apart.

Lightweight, discrete form factor: The device weighs eight grams — about two sheets of paper — configured in a linear shape designed to improve P-wave detection while keeping a sleek, unobtrusive profile. "When people wear it, they don't know they are wearing one," Young says.

Reusable device with commodity electrodes: Instead of locking patients into proprietary pads, Wellysis designed the S-Patch to work with standard Holter electrodes — the same type hospitals already use — which typically cost just 20 to 30 cents apiece on the open market. Most competitors follow a razor-and-blades model: sell the device at a lower price but require proprietary electrodes sold at a premium. Wellysis flipped that logic. “Patients can eventually own one of these and test themselves a few times a year,” Young explains.

These design decisions were supported by Samsung’s custom bioprocessor chip — a compact component built specifically to process human vital signs such as ECG, photoplethysmography (PPG), temperature, and bioelectrical impedance analysis (BIA). The chip’s efficiency made it possible to maintain the S-Patch’s small, lightweight profile while still delivering medical-grade data. Today the device uses ECG only, but the underlying architecture leaves room to add other signals as clinical needs evolve.

The result: Holter-like ECG accuracy for up to 14 days — without requiring patients to feel like they’re sick.

Don’t Assume What Works Abroad Will Work in the U.S.

Young assumed his experience at Johnson & Johnson and Kaiser Permanente had prepared him for U.S. commercialization. But scaling S-Patch overseas highlighted how different healthcare systems truly are.

“In Korea, hospitals build their own EMRs,” Young explains. “In the U.S., we had to integrate with Epic, Cerner, and multiple other systems — each with distinct workflows.”

The payer landscape proved even more challenging. Korea’s single government payer meant clarity; the U.S. required navigating Medicare, Medicaid, and dozens of private insurers. Even with FDA clearance, it took a full year to integrate into reimbursement processes.

Hardware also required redesign. Asian patients had more uniform body types. In the U.S., device length had to adjust for larger chests — even the power button had to change for athletes with bigger thumbs.

“These weren’t minor tweaks,” Young says. “They forced us to revisit core design assumptions.”

Use Healthcare Culture to Build an AI Advantage

Unlike the fragmented U.S. system, Korean patients often stay with the same hospital for decades. At Samsung Medical Center, Wellysis could access 20-30 years of ECG data from the same individuals.

“That was the benefit,” Young says. “We were able to see how the same patient’s ECG changed over decades.”

Korea’s routine health-check system — often annual for employees — plus Samsung Medical Center’s practice of sending patients home with S-Patch for two days created rare longitudinal datasets.

That foundation powered Wellysis’ AI strategy. Instead of snapshot analysis, the system processes streaming ECG at 256 Hz. According to Young, the model can now identify patients likely to develop atrial fibrillation within a year — with about 90% accuracy.

“Regular doctors cannot see those changes, but AI can,” he explains.

Expect Cybersecurity to Be a Regulatory Hurdle

The toughest surprise came late in the U.S. clearance process — cybersecurity.

“We didn’t expect cybersecurity to be that tight,” Young admits. Encryption standards, secure data transmission, and hardware protections all had to meet far stricter requirements than the team had anticipated.

The concern wasn’t hypothetical. Industry reports had described a case where a high-ranking official’s medical device was hacked, exposing sensitive health data. That incident underscored why regulators demanded such rigorous safeguards.

Wellysis ended up redesigning everything from chip-level encryption to Bluetooth communication modules. The work delayed commercialization but ultimately strengthened trust. “If patients can’t trust the security, nothing else matters,” Young says.

Looking ahead, Young believes the bigger debate will be ownership of home-collected data. “I believe patients should be the owner,” he says.