The Applications of Wearable Biosensors

Biosensors are devices designed to detect and quantify biological or chemical substances by converting a biological response into an electrical signal. They normally consist of three components: a biological element such as an enzyme, antibody, or nucleic acid; a transducer that converts the biological interaction into a signal; and a signal processor that interprets the data. Biosensors are valuable across diverse fields, including health diagnostics, environmental monitoring, and food safety assessments.

Wearable biosensors, also known as wearables, have gained significant traction due to their potential to provide non-invasive, continuous, and real-time monitoring of physiological and biochemical markers. These markers include glucose, cortisol, heart rate, and hydration levels, which are analysed through biofluids such as sweat, saliva, and interstitial fluid. These systems are integrated into portable, skin-adherent devices such as smartwatches, patches, or smart garments, and utilise technologies such as electrochemical, optical and piezoelectric sensing. Electrochemical biosensors detect substances like lactate and glucose, converting the molecular concentrations into electrical signals. Optical biosensors use light to identify the presence of molecules by detecting changes in light absorption and fluorescence. This principle is used in pulse oximeters to measure blood oxygen levels. Piezoelectric biosensors rely on the piezoelectric effect to detect changes in pressure, mass, or stress, converting them into electrical impulses, commonly used to monitor breathing and physical activity. These biosensors are designed for specific applications, enabling a wide range of health-related uses.

Unlike traditional diagnostics, wearable biosensors facilitate real-time health tracking and are often connected to smartphones or cloud platforms for seamless data visualisation and analysis. Their portability enables users to monitor their health anytime and anywhere, reducing dependency on clinical settings and empowering individuals with actionable insights. These systems have become crucial in managing chronic diseases, supporting preventive care, and enhancing personalised medicine. As flexible materials, miniaturised electronics, and AI-driven analytics continue to evolve, wearable biosensors are transitioning from simple health trackers to essential tools in next-generation healthcare.

One of the most well-known examples of biosensors in the medical field is the use of glucose biosensors in diabetes management. At-home blood glucose biosensors to monitor blood-glucose account for around 85% of the global biosensor market. Continuous glucose monitors, such as the FreeStyle Libre and Dexcom G6, use interstitial fluid to deliver real-time glucose readings. Worn on the upper arm or abdomen, these sensors empower individuals to make informed decisions about insulin administration and diet, significantly reducing the risks associated with hypoglycaemia and hyperglycaemia. Wearable biosensors are also powerful tools for fertility and maternity monitoring, cancer diagnostics, and infectious disease detection. For example, fluorescent biosensors, including genetically encoded FRET sensors, are used in oncology to monitor intracellular enzyme activity associated with tumour metabolism and drug response. These insights guide personalised cancer therapy and drug efficacy evaluations. Additionally, ECG wearables enable early detection of arrhythmias and irregular heart patterns, improving patient outcomes through timely interventions and reduced healthcare costs.

The diagnostic capabilities of wearable biosensors extend beyond non-clinical environments, allowing for point-of-care testing and at-home diagnostics. These compact, portable devices generate rapid results and are increasingly integrated into telemedicine platforms, enabling healthcare providers to remotely monitor patients, particularly in elderly care or rural settings. Their quick output facilitates immediate treatment decisions, leading to faster interventions and improved patient outcomes.  Recent innovations include biosensors that diagnose urinary tract infections (UTIs) by identifying pathogens and determining antibiotic susceptibility without centralised lab processing. Additionally, devices like Epicore Biosystems’ Discover Patch, collect and analyse sweat to monitor hydration and electrolyte levels during physical activity.

Wearables also play an important role in implantable devices, such as bioelectric implants and prosthetics. While more invasive, these devices can detect specific biomarkers of physiological signals, providing essential information to healthcare professionals. For example, Biospectal’s optical blood pressure monitor offers non-invasive blood pressure tracking from the fingertip, which could benefit over 120 million Americans living with hypertension.

In sports and fitness, wearable biosensors offer athletes and fitness enthusiasts detailed physiological data that can inform training regimes, prevent injuries, and optimise recovery. Devices embedded with inertial sensors and gyroscopes assess biomechanics, such as stride and joint angles, enhancing performance while minimising strain for runners and cyclists. These wearables also monitor sleep patterns, heart rate variability, and recovery indicators to help users manage exertion and avoid overtraining. Such insights not only refine athletic technique but also promote long-term physical wellness.

Beyond healthcare and fitness aspects, wearable biosensors are transforming personal wellness and preventive health. Devices equipped with electrodermal activity (EDA) sensors and temperature monitors track stress and sleep quality, offering personalised recommendations. This influences decision making to make healthier lifestyle choices that may lead to improved wellness. By analysing heart rate, physical activity, and sleep disruptions, users receive tailored feedback to manage stress and enhance overall well-being. These tools support proactive health management and long-term behaviour change. For example, by monitoring sleep time, stages, and sleep disruptions, it provides suggestions for individuals, along with sleep solutions to improve the quality of their sleep.

The advantages of wearable biosensors are extensive, with their most compelling benefit being the ability to monitor health anytime and anywhere. They provide pain-free, real-time insights into biomarkers using accessible biofluids, eliminating the need for invasive procedures. Continuous monitoring enables early detection of health abnormalities and supports personalised treatments based on dynamic data rather than reactive symptom management. One of their key strengths is early detection and personalised management of chronic diseases by tracking multiple physiological variables, such as glucose levels, hydration, temperature, cardiac activity, and biomarkers of inflammation or infection. This continuous data stream supports precision medicine by allowing treatments to be tailored based on molecular-level insights rather than solely observable symptoms. Miniaturised sensors provide real-time analysis of molecular markers through easily measurable parameters such as temperature, dehydration, or glucose levels.  

Wearable biosensors also facilitate direct communication between users and healthcare providers, reduce hospital visits, and lower healthcare costs by replacing bulky traditional diagnostic equipment with compact alternatives. In clinical contexts, they minimise the need for prolonged hospital stays and repetitive testing, particularly for chronic disease management. Their cost-effectiveness and portability ease the burden on healthcare systems by optimising resource allocation, in contrast to traditional equipment like ECG monitors and defibrillators, helping healthcare systems reduce resource strain. Furthermore, wearable biosensors enhance public health by enabling early detection of outbreaks, such as COVID-19 and SARS, through continuous symptoms and vital sign tracking. 

Their applications in cardiovascular monitoring are particularly impactful, as cardiovascular disease remains the leading cause of death globally, claiming over 17 million lives annually. Highly sensitive biosensors using nanomaterials and advanced chemistries enable rapid and accurate diagnostics at the point of care. In rehabilitation and physical therapy, these devices monitor joint motion and strain, supporting injury recovery and informing therapeutic strategies.

Despite their promise, wearable biosensors face several challenges. Ensuring sensor accuracy and stability, especially in non-invasive systems, requires precise calibration and stable skin contact. Other challenges include bioreceptor fragility, susceptibility to biofouling, and inefficient analyte transport, all of which affect signal reliability. Researchers are addressing these issues with antifouling coatings, multimodal sensing, and integrated calibration systems.

Wireless communication also presents limitations, as devices must balance short-range protocols with the need for remote data transmission. Power supply remains another major concern, with continuous operation demanding efficient, long-lasting energy sources such as wearable batteries, energy harvesting systems, and smart power management strategies. Meeting these power requirements in a safe manner requires various approaches such as using safe high-energy wearable batteries, wireless energy transfer, alternative energy storage devices (biofuel/ solar cell), or even self-powered biosensors using biofuel cells. Whilst real-time monitoring is a key benefit, data privacy and security are fundamental. Sensitive health data must be protected from unauthorised access and misuse. Some approaches involve data cleaning and filtering processes to safeguard information while maintaining seamless connectivity.

Looking ahead, the innovation of wearable biosensors will continue to expand and promote widespread adoption. Non-invasive monitoring using sweat, saliva, and interstitial fluid will become increasingly common, enabling painless health tracking across a wide range of biomarkers. Integration with artificial intelligence (AI) and machine learning will help develop predictive capabilities, reduce false readings, and personalise feedback based on user behaviour. Remote patient monitoring will become more prevalent, especially in telehealth, supporting chronic disease management and reducing hospital dependence.

Miniaturisation and portability will continue to improve with the development of lab-on-a-chip technologies and smartphone integration, facilitating real-time health insights and cloud-based analytics. Internet of Things (IoT) connectivity will link biosensors to broader healthcare ecosystems, enabling predictive and preventive care at scale. As biosensor platforms grow more sophisticated utilising DNA-based, optical, and electrochemical technologies, healthcare will shift toward more proactive and personalised models.

In summary, wearable biosensors are revolutionising healthcare, wellness, and performance monitoring. Their ability to provide continuous, real-time, and non-invasive data makes them invaluable tools for early diagnosis, personalised treatment, chronic disease management, and lifestyle optimisation. While challenges remain regarding technology, cost, and regulation, ongoing advancements in AI, materials science, and digital health infrastructure position wearable biosensors as a cornerstone of future healthcare delivery.