Researchers at Dartmouth College have developed a smartphone-based tool that can monitor tissue health by measuring oxygen levels in cells. The method uses a naturally occurring molecule and, according to the researchers, could offer a simple and affordable solution for home monitoring.
Whereas traditional pulse oximeters measure blood oxygen levels, this new approach focuses on oxygen in tissues. “The pulse oximeters used in emergency rooms, ambulances, and home care measure blood oxygen levels accurately, but that doesn’t really change much until you’re essentially on your deathbed,” says Brian Pogue, a professor of biomedical engineering at Dartmouth. “What we really want isn’t blood oxygen levels, but tissue oxygen levels. That’s a much more subtle indicator of tissue function and a better dynamic indicator of health.”
Measuring with a smartphone and light
The technology, described in Biosensors and Bioelectronics, combines a standard smartphone camera with a pulsating LED light source and a special cream. This cream stimulates the production of Protoporphyrin IX, a molecule that occurs naturally in cells and is sensitive to oxygen. “When protoporphyrin IX is not blocked by oxygen, it emits a faint light signal. That is what our measuring instrument detects,” says Pogue. By analyzing these light signals, the system can detect changes in oxygen levels in tissue.
Measuring tissue oxygen is relevant in conditions such as peripheral vascular disease, wound healing, and infections. This information helps doctors, for example, make decisions regarding surgeries or amputations. According to the researchers, the smartphone tool could be particularly valuable for daily monitoring, for example in patients with reduced blood flow. The method can also provide insights into wound healing. Inflamed tissue typically has a higher oxygen level, which decreases as recovery progresses. “It’s the development over time that counts,” says Pogue.
Further Development
The researchers are currently expanding their studies, including applications in burn care and the assessment of infections. They are also working on a user-friendly app so that patients can easily use the technology at home.
According to the researchers, the combination of low cost, ease of use, and continuous monitoring can contribute to better decision-making and broader access to diagnostics outside the hospital.
Smartphone monitoring
In 2025, researchers at Stanford University developed a smartphone-based method to monitor patients with neuromuscular diseases more accurately and accessibly than traditional tools. By combining smartphone cameras with AI-driven biomechanical modeling, the system, using the OpenCap app, can analyze movement in detail without the need for specialized equipment.
In a study involving over 130 participants, videos of simple movements were converted into 3D “digital twins,” enabling analysis of more than 30 biomechanical features such as stride length and range of motion. The results showed that smartphone-based measurements matched traditional stopwatch assessments while providing significantly deeper insights.
Notably, the system could distinguish between different neuromuscular diseases with 82% accuracy, compared to 50% using conventional methods. The researchers suggest this approach could enable precise, low-cost monitoring of patients both in clinical settings and at home.
