With cutting-edge sensing technology shaping the modern healthcare landscape in fascinating and often unpredictable ways, it can be tempting to presume that the bulk of the advancement has occurred in recent years. However, history says otherwise. X-rays were discovered in 1895 by Wilhelm Conrad Roentgen, and the first images generated by clinical x-ray were recorded shortly after. In 1903, Dutch physician Willem Einthoven invented the electrocardiograph, a new device that could record the heart’s electrical impulses. Using Einthoven’s device, German physiologist and psychiatrist Hans Berger developed a method for recording human brainwaves just a few decades later.

One doesn’t have to imagine the wonder physicians and patients alike must have experienced in the late 19th century when sensing technology emerged and began making an indelible impact on healthcare, because we are living through a similar moment now. Machine learning, robotics, remote sensing tech and the development of wearable and self-powering medical devices are transforming the jobs of medical experts and enhancing patient care.

Huanyu “Larry” Cheng is an associate professor of engineering science and mechanics at Penn State University whose research is focused on developing new stretchable and conformable electronic sensing devices. After completing his PhD training in 2015, Cheng established a research group with a focus on engineering low-cost, deformable multimodality sensors for biomarker measurements and health monitoring. In his eight years since joining the department, Cheng has built sensing tech that would fit comfortably in a science fiction film, including a technique for printing biodegradable electronics onto complex surfaces and a wearable head-scanner.

“This new class of stretchable devices provides an alternative approach for integrating electronics on a soft, stretchable substrate and is designed to match the physical properties of soft skin and tissues,” explains Cheng. He adds that the technology is built to monitor a variety of vital signs, including temperature, heart and respiration rates, blood pressure and oxygen saturation as well as electrophysiological signals.

Cheng’s team has focused on developing manufacturing methods for its sensing devices that are innovative yet simple and universal, like adapting commercial off-the-shelf chips for extended data processing for use in wearables. Designed to integrate with soft skin-interfaced microfluidic devices, the research group’s biophysical and biochemical sensors can perform functions such as sweat collection and analysis at a significantly improved accuracy, according to Cheng. “Skin-interfaced microfluidic platforms are capable of capturing, storing, and assessing other biofluids like tears, saliva, and interstitial fluids to provide essential insight into human physiological health,” he says. The sensing devices developed by the Penn State research group are engineered to give preventive monitoring and early diagnostic data to patients who don’t have to be confined to a specific space, like their homes or a doctor’s office for the technology to work.

Cheng’s team currently has multiple sensing devices on track for FDA approval, including a novel wearable sensor platform designed to improve diagnosis options for high-risk deep vein thrombosis (DVT) that’s being developed in collaboration with Actuated Medical Inc (AMI). “My group has developed a laser-induced graphene-based, wireless, resistive sensor technology capable of 2D mapping of skin temperature when worn directly or integrated into conformal clothing,” explains Cheng. Carefully constructed to conform to the patient’s body on contact, the wearable device leverages electrical van der Waals interactions – weak electrostatic forces that attract neutral molecules to one another – to provide adhesion and consistent monitoring without the use of chemical adhesions. By making it as easy as possible to record biomarkers, Cheng believes the convenience and ease of use for patients will bolster compliance and, ultimately, health outcomes.

Off the cuff

Steven LeBoeuf is president and co-founder of Valencell, an American medtech company that’s developed a small, portable and cuffless blood pressure monitoring device to help patients monitor chronic diseases such as hypertension remotely. Not yet cleared by FDA, the fingertip blood pressure monitor was engineered to make blood pressure management easier and more convenient. “Our solution, comprising a fingertip sensor and a mobile app, provides accurate blood pressure spot check measurements without ever requiring the need for a cuff or calibration,” he explains.

Valencell’s smart sensing device delivers blood pressure readings with the help of its proprietary machine learning software. In an average time of one minute, the device collects photoplethysmography (PPG) sensor information collected from a patient’s finger, combines it with their unique age, weight, sex and height data points and transmits the resulting blood pressure reading to the patient’s mobile app. According to LeBoeuf, Valencell’s software is powered by a machine learning model that has been trained on over 10,000 datasets from over 5,000 human participants across the globe.

Monitoring devices with PPG sensing technology collect patient data by emitting light onto skin tissue while a photodetector measures the light that’s being reflected. Valencell evolved from a developer and supplier of PPG sensing tech for fitness wearables to its current identity as a digital health technology solution brand focused on chronic disease management and prevention. “Valencell has been breathing life into wearable PPG sensors for over 15 years,” LeBoeuf notes, adding that the company’s claim to fame was the development and commercialisation of the world’s first optical-based heart rate monitoring technology, which is now a common fixture in gyms and on fitness gear.

Taking a wider view of the industry, he points to four areas of technological advancement that have made sensing devices like Valencell’s possible: wireless and mobile tech, wearable tech, machine learning, and digital health tech. Adherence has long been a practical limitation of remote sensing technology in healthcare, he explains: “A lowburdensome wearable sensor is practically useless without seamless wireless data logging. If people need to keep re-establishing wireless connections due to drop-outs, the best sensors in the world might as well be doorstops.”

Devices that are difficult or burdensome to use are an issue not just for end-users, but also for healthcare providers. “Even a perfect userfriendly sensor with seamless wireless connectivity to a healthcare professional is a commercial nonstarter without an autonomous way of making sense of the data. And that’s where machine learning comes in,” adds LaBoeuf.

Continuous monitoring

Headquartered in California, Bigfoot Biomedical is another medical device company focused on leveraging complex sensing technology to provide simple, personalised, and convenient healthcare data for patients. “We’re challenging the current approach to diabetes innovation by focusing on simplicity over complexity so that people with diabetes can live the lives they choose,” the company’s CEO, Jeffrey Brewer, explains. “Bigfoot aims to provide simple, easy-to-use tools to reduce the cognitive, emotional, and financial burden for diabetes patients who require insulin.”

While there are other monitoring systems on the market that provide alerts and information, the primary function of the Bigfoot Unity System is to give patients actionable advice and insights based on their blood data, which is continuously monitored in real time. When a Bigfoot user asks how much insulin they should take at any given moment, the system is designed to deliver a personalised answer instantly.

“We hear from users that data is good, but knowing what to do with it is better,” says Brewer, adding that Bigfoot’s simple approach to functionality and use differs from that of many other market participants. Innovation for diabetes treatment tends to focus on sophisticated systems built “power users” instead of the majority of patients, who are left frustrated and overwhelmed, according to Brewer. The approach struck a chord with medical device giant Abbott, too, which partnered with Bigfoot Biomedical in 2021 and inked a deal to acquire the company in September 2023.

Bigfoot’s platform includes Freestyle Libre 2 CGM (continuous glucose monitoring) sensors, a white pen cap for rapid-acting insulin, a black pen cap for long-acting insulin and a mobile application, which wirelessly integrates with a blood glucose meter. Patients are given instructions directly on the pen cap, as well as CGM data and app-based alerts and reminders. Brewer credits the everimproving accuracy of CGM sensors for paving the way for Bigfoot Unity, which allows the company to deliver streams of accurate glucose data and reduce the need for fingerstick confirmations. Brewer had a personal motivation for pursuing the development of Bigfoot’s diabetes technology, as his son was diagnosed with type 1 diabetes in 2002. But looking broadly at the development of sensor technology, he sees devices that take advantage of what’s possible now and what will be in the future as a catalyst for personalising patient care. “Sensors play a crucial role in healthcare by empowering physicians and patients with real-time data, especially those living with diabetes,” Brewer adds. “These technologies improve overall health outcomes while promoting proactive and preventive approaches to health management.” ­