A Breakthrough in Medical Monitoring: Next-Gen Medical Stabilization with Nanoparticle-Based Wearable Biosensors

Against the backdrop of aging, chronic diseases, and a growing population, the healthcare system is going through a vital transformation.

Healthcare is simply becoming increasingly individual-centric. This trend is driven by wearable devices, which allow for continuous measurement of critical biomarkers for medical diagnostics, monitoring of the diseased condition, health, and surrounding environment, and evaluation of biological fluids like sweat, saliva, tears, and blood.

These wearable devices are portable electronic devices that utilize sensors to collect real-time data on various physiological parameters, which, in turn, allow for continuous monitoring of activity levels and health.

More importantly, these biosensors help regular individuals monitor their own health from anywhere and at any time. In particular, these devices can help patients with chronic diseases reduce the number of hospitalizations and save costs. Overall, people can better manage their lives and health with wearable devices.

Meanwhile, physicians can detect potential health issues early, respond immediately, and provide personalized healthcare plans, while hospitals can save on equipment costs.

Depending on the parameters measured, wearable biosensors can be of different types, such as optical, electrochemical, electromechanical, chemical, and optoelectronic sensors. These devices can be worn on the human body or implanted inside it to monitor biological signals by taking non-invasive measurements of biochemical markers.

In terms of their design or utility, wearable devices can be classified into a few different ways. 

To start with, wrist-mounted wearable devices (WWD), as the name suggests, are typically worn on the wrist. Smartwatches or fitness bands are examples of these wearables, which have evolved from basic accelerometer-based ones to now include biometric sensing used as non-invasive human monitoring devices.

Wristbands, in particular, are designed to track human health and fitness activities. They have rather limited features and, at times, may not even have a display screen for notifications either. Fitbit, Amazon Halo Band, and Huawei Talkband B3 are popular examples.

Wristwatches or smartwatches are one of the most popular wearable device types, which monitor specific human physiological signals and biomechanics. They use sensors and batteries to collect information and transfer it to the smartphone for analytics and readability. Some popular examples of smartwatches are the Apple Watch, Samsung Galaxy Watch, and Garmin Fenix. They allow the tracking of metrics like ECG, blood oxygen, SpO2, stress, sleep, and heart rate, among others.

Then, there are patches for the real-time analysis of body fluids like sweat and temperature. This includes glucose monitoring patches Abbott FreeStyle Libre and Dexcom G7, Gatorade Gx Sweat Patch to analyze sweat composition to provide hydration recommendations, and TempTraq for continuous temperature monitoring.

Besides hands, the head is another body part where these devices are worn. Head-mounted tools like helmets, glasses, and caps are visual devices that offer hands-free capabilities.

When it comes to smart glasses, we have seen the likes of Ray-Ban Meta Smart Glasses, Vuzix Blade & Vuzix Shield, Rokid Max, and Xreal offering built-in cameras, speakers, streaming, AI, among other features for industrial, medical, computing, enterprise, and gaming fields.

Even smart helmets are gaining traction as not just protective headgear but also to provide intelligent services by integrating with electronic sensing, alerting, and communication devices. Helmets are also being explored to treat depression by transmitting weak electrical pulses to the brain.

Smart clothing or E-Textiles are yet another wearable that uses smart materials that respond to mechanical, thermal, and chemical changes. E-textiles can also sense external stimuli from the environment.

In the realm of E-textiles, we have Hexoskin smart shirts that track heart rate, breathing rate, and movement for athletes and medical use. These washable garments provide continuous cardiac, pulmonary, activity, sleep data, electrocardiograph reporting, and respiratory ventilation. Hexoskin offers non-invasive and comfortable smart clothing for men, women, and kids, with additional anti-odor and UV protection features. When it comes to technology, they offer up to 36+ hours of battery life, over 100 days of recording, and Bluetooth connectivity.

Besides shirts, socks, sleepwear, jackets, and shoes are becoming smart. So, the world of wearable devices is clearly a fast-growing one as people increasingly prioritize their health and well-being. This growth is further fueled by the ease of data availability in real-time, advancements in sensor technology, and expanding healthcare applications.

Printable Nanoparticles for Wearable Biosensors

As wearable biosensors pioneer new frontiers in precision medicine, researchers from Caltech have developed a technique that enables the mass production of long-lasting wearable sweat sensors.

With this tech, which is inkjet printing arrays of special nanoparticles, the research aims to address the challenges of production scalability, operational instability, and a limited number of detectable targets that are obscuring the widespread adoption of wearable and implantable biosensors.

The printable core-shell nanoparticles come with built-in dual functionality — a molecularly imprinted polymer shell to recognize a specific target and a core of nickel hexacyanoferrate (NiHCF) to stabilize electrochemical transduction. 

By making use of an optimized nanoparticle ink formulation through inkjet printing, Caltech engineers showed the possibility of the mass production of flexible and robust biosensors that can continuously monitor a broad spectrum of biomarkers. This includes drugs, vitamins, amino acids, and metabolites.

The team further demonstrated the effectiveness of these biomarkers in wearable metabolic monitoring of creatinine, tryptophan, and vitamin C in individuals suffering from long-term COVID-19. 

They also successfully used the new nanoparticles and validated the utility of the biomarkers in therapeutic drug monitoring for cancer patients as well as in a mouse model by providing real-time analysis of immunosuppressants like mycophenolic acid, cyclophosphamide, and busulfan.

But this is not all that’s possible with the tech.

“There are many chronic conditions and their biomarkers that these sensors now give us the possibility to monitor continuously and noninvasively.”

– Wei Gao, corresponding author and a professor of medical engineering in the Andrew and Peggy Cherng Department of Medical Engineering at Caltech

According to the paper published¹ in the journal Nature Materials detailing the technique, the nanoparticle cubes are formed in a solution that includes the specific molecule, such as vitamin C, that the researchers want to track.

The target molecule is then trapped inside the cubic nanoparticles as monomers assemble spontaneously to form a polymer. A solvent is next used to remove the target molecules, specifically leaving behind a molecularly imprinted polymer shell.

This shell is dotted with holes possessing shapes that match exactly that of the target molecule, much like how artificial antibodies selectively identify the shapes of only specific molecules.

Notably, the researchers in the new study combine the specially formed polymers with a nanoparticle core made of the chemical compound NiHCF. The compound is known for its unique properties, which include good electrical conductivity, high thermal stability, the ability to undergo reversible redox reactions, and magnetic behavior. These properties make NiHCF a promising material for magnetic storage media, catalysis, and electrochemical energy storage devices like batteries, as well as sensors and biosensors.

More importantly, NiHCF can also be oxidized under an applied electrical voltage when it comes in contact with bodily fluids like sweat.

In this study, fluid will come into contact with the NiHCF core only if the holes in the shape of the target molecule are unoccupied, which will generate an electrical signal.

However, when the molecules meet the polymer, they slip into those holes. This prevents bodily fluids like sweat from making contact with the core, in turn weakening the electrical signal. So, how strong the electrical signal is reveals just how much the targeted molecule, like vitamin C, is present. Gao explained:

“This core is critical. The nickel hexacyanoferrate core is highly stable, even in biological fluids, making these sensors ideal for long-term measurement.”

The core-shell nanoparticles created are highly flexible. They are used to print sensor arrays that calculate the amount of hormones, amino acids, drugs, or metabolites in sweat or bodily fluids just by using multiple nanoparticle “inks” in a single array. 

For instance, the researchers also printed nanoparticles that bind creatinine, the commonly used biomarker, to examine how well the kidneys are functioning. The team combined these nanoparticles, along with those that bind with Vitamin C and those that bind with tryptophan, into a single sensor, which was then mass-produced to study patients with long COVID.

Nanoparticles-based wearable sensors were also printed for three specific but different anticancer drugs on individual sensors that researchers put to the test at the cancer research and treatment center in the City of Hope.

According to Gao, who is also a Ronald and JoAnne Willens Scholar and a Heritage Medical Research Institute Investigator:

“Demonstrating the potential of this technology, we were able to remotely monitor the amount of cancer drugs in the body at any given time.”

This not only points to the way to achieve dose personalization for cancer but also for many other conditions, he added.

In addition to it all, the team demonstrated that the nanoparticles can even be used to print sensors implantable just below the skin in order to accurately monitor drug levels in the body.

Click here to learn how innovative healthtech is on the rise with advanced wearables.

Company Leading the Wearable Tech

Now, let’s take a look at the most prominent name in the wearable technology sector that continues to make advances.

1. Apple (AAPL +1.27%)

The world’s largest company by market cap of $3.63 trillion, Apple has its shares currently trading at $241.53, down 3.55% YTD. Its EPS (TTM) is 6.96, and the P/E (TTM) ratio is 34.69. The dividend yield paid by Apple is 0.41%.

Apple joined the wearable sector over a decade ago by launching the Apple Watch Series 0, the first in the line. While the smartwatch sector was already crowded at the time, Apple was still able to establish its presence despite the late entry. 

Over the years, Apple has been able to capture a nice chunk of this market, but in recent years, it has been seeing a decline. In 2020, its market share was over 34%, which fell to about 30% the following year.

According to IDC, Apple’s market share from Q1 to Q3 of 2024 was 16.2% as it recorded 22.5 million shipments, which dropped from 18.4% in the same period last year. With this, Apple now stands in second place as Huawei overtakes with 23.6 million shipments and captures a 16.9% market share. These two are followed by Xiaomi, Samsung, and BBK. So, while Apple is still maintaining a strong presence, it is now facing stiff competition.

Amidst all this, Apple continues to work on its wearable technology, now broadening its health research ambitions to use its devices for a study to monitor changes in participants’ health. The company aims to tap into the devices and apps that people use every day to evaluate the connections between mental and physical health as well as social determinants and just how they factor into the overall well-being of a person.

This is to help them identify signals in a person’s health data to potentially detect a health condition. The Apple Health Study will be made available in the Research app, which has helped the team gain “valuable insights” to develop new tools like Walking Steadiness on iPhone and the Vitals app on Apple Watch.

Last year, the company also began exploring the idea of developing new wearable devices like smart glasses, a fitness ring, and even AirPods with cameras.

A smart ring to be worn on the finger was initially recommended by the design group a few years ago that would take health-tracking features from the Apple Watch, but most recently, engineers discussed the possibility of smart glasses that could provide audio, use a camera and AI to identify things, and ultimately act as a diving board for Apple’s ambition to create true AR glasses that one can wear all day long.

The company has also been hard at work on AirPods earbuds, Vision Pro headset, Beats headphones, HomePod speaker, and the Apple Watch to boost its wearable device business. 

Interestingly, Apple has patented a new smartwatch technology that could enable blood pressure monitoring on the Apple Watch without relying on optical sensors. For now, the Apple Watch offers powerful apps such as heart rate and irregular rhythm notifications, AFib history, ECG app, low cardio fitness notifications, blood oxygen level, and fall detection to help people live healthy lives.

But this is not all. Apple’s AirPods Pro 2 earbuds even offer the functionality of over-the-counter hearing aids. While the hearing test has come impressively accurate, it is suitable for people with only mild to moderate hearing loss.

Now, the company’s financial health — Apple recently reported the financial results for its fiscal 2025 Q1 ended December 28, 2024. In this “best quarter ever,” Apple had $124.3 billion in revenue and diluted earnings per share of $2.40, up 4% and 10% YoY respectively. 

The revenue included $69.14 billion from iPhones, $8.99 billion from Mac products, $8.09 billion from iPads, and $11.75 billion from other products, also called Wearables, which includes the Apple Watch, AirPods, Beats, and Vision Pro sales. The wearables category saw a drop of 2% on a year-over-year basis. 

Meanwhile, $26.34 billion was spent on services, which included subscriptions, warranties, and licensing deals. In the earnings call, CEO Tim Cook stated that the company had more than one billion subscriptions. This includes subscriptions for services like Apple TV+ and iCloud and subscriptions to third-party apps through the App Store.

The company’s strong operating margins also sent its EPS to a new all-time high with double-digit growth, which allowed the tech giant to return over $30 billion to its shareholders, with the board of directors declaring a cash dividend of $0.25 per share.

Apple’s installed base of active devices also reached a new high across all products and geographic segments. However, its device sales declined by 11.1% in China. iPhone sales were, however, stronger in regions where Apple Intelligence is available, said Cook.

“Through the power of Apple silicon, we’re unlocking new possibilities for our users with Apple Intelligence, which makes apps and experiences even better and more personal.”

– Cook

So, Apple is now working with Alibaba and Baidu to bring AI features to its iPhones in China by the middle of this year.

Conclusion

The personalization of healthcare is the future of medicine. This, after all, can improve patient outcomes, reduce disease burden, and lower healthcare costs, but of course, this means knowing exactly what one needs and then delivering the right mix of medications, nutrients, and metabolites.

For this, we first need a way to continuously measure and monitor certain biomarkers of health, where wearable technology can be of immense help, as the new study has demonstrated. 

By developing printable core-shell nanoparticles, researchers have taken a major step toward the mass production of long-lasting, wearable biosensors. The versatility of these sensors, from monitoring chronic conditions to personalizing drug dosages for cancer patients, opens new doors in precision medicine.

Such advances in technology can offer both patients and healthcare providers continuous and individualized health insights and bring us closer to a future where personalized, data-driven health management is seamlessly integrated into our daily lives!

Click here for a list of top wearable health tracking companies.