Researchers at the King Abdullah University of Science and Technology have developed a wearable biosensor patch designed to detect allergic reactions before symptoms occur. The device, called the AllergE patch, uses microneedle technology to monitor levels of immunoglobulin E (IgE), the antibody responsible for triggering allergic responses, directly beneath the skin.
The research, published in ACS Materials Letters, suggests that such technology could help shift allergy management from reactive treatment to early detection and prevention.
Monitoring allergy signals beneath the skin
Food allergies, particularly to eggs, nuts, milk and seafood, are an increasing public health concern. Current diagnostic methods, such as skin-prick tests and blood sampling, are invasive, time-consuming and can themselves provoke mild allergic reactions.
The AllergE patch offers a different approach. The device contains an array of tiny porous microneedles, each less than one millimeter long and roughly the width of a human hair, that penetrate only the upper layer of the skin. This allows the sensor to access interstitial fluid without causing pain.
Within each microneedle are DNA strands known as aptamers, which act as molecular detectors. When these molecules encounter IgE antibodies, they change shape and produce an electrochemical signal. A flexible electrode and a small electronic reader translate this signal into measurable data. According to the researchers, future versions of the system could connect to smartphones, enabling remote monitoring of allergy-related biomarkers at home.
Real-time allergy monitoring
The patch continuously measures immune signals associated with allergic reactions. This could potentially allow patients and caregivers to detect rising allergy markers before exposure leads to a dangerous response such as anaphylaxis.
"This smart patch could one day help prevent anaphylaxis and enable safe, at-home early allergy sensitization detection," says Dana Alsulaiman, corresponding author of the study. Early detection of IgE changes may help individuals with severe allergies monitor risk levels and respond sooner when exposure to allergens occurs.
High sensitivity in laboratory testing
In laboratory experiments using artificial skin substitutes and explanted human skin samples, the device demonstrated high sensitivity. It was able to detect IgE concentrations as low as 30 picograms per milliliter, hundreds of times more sensitive than many current laboratory assays.
The system also showed strong specificity, successfully distinguishing IgE antibodies from structurally similar immune proteins that do not trigger allergic reactions.
The microneedles themselves are manufactured using two-photon polymerization, a high-resolution 3D lithography technique that allows researchers to precisely control their structure and mechanical strength. This ensures the needles penetrate deep enough to collect interstitial fluid while remaining painless and stable during repeated use.
Future wearable diagnostics
Although still at an early stage of development, the research team sees the AllergE patch as part of a broader class of skin-mounted diagnostic devices. These could potentially monitor a wide range of biomarkers related to immune responses, inflammation, hormones or disease processes. The project was developed through collaboration between the Lab of Biomedical Materials and Devices (BioMAD Lab), led by Dana Alsulaiman, and the Sensors Lab led by Khaled Salama.
The idea for the device was partly inspired by personal experiences with severe food allergies. Esraa Fakeih, a former PhD student in Salama’s lab, encountered the risks of allergic reactions within her own family when she and her nieces experienced serious reactions after consuming foods containing trace amounts of allergens.
"These situations inspired the idea of a wearable patch that can help prevent severe reactions," Fakeih says. For people living with severe allergies, a wearable biosensor capable of detecting early immune signals could provide valuable time to respond, potentially preventing life-threatening reactions or offering crucial early warnings when exposure occurs.
Smart patch technology
Last year, researchers at Northwestern Medicine and Epicore Biosystems developed a wearable sweat patch that enables remote monitoring of patients with cystic fibrosis (CF). The wireless, wrist-mounted device uses microfluidic technology to measure sweat volume and chloride levels, with accuracy comparable to traditional laboratory tests. Colour changes in the patch can be analysed through a simple photo taken with a smartphone or tablet, allowing physicians to review the data and make treatment decisions remotely.
Another example of smart patch technology is the sensor patch, developed by researchers at the University of New South Wales, together with international partners and Nutromics, that continuously measures vancomycin levels in the body every five minutes. Vancomycin is a powerful antibiotic used for severe infections, but incorrect dosing can lead to ineffective treatment or serious kidney damage. The patch uses microneedles with DNA-based sensors (aptamers) to sample body fluids just beneath the skin, offering a nearly painless alternative to repeated blood tests. Continuous monitoring allows doctors to adjust dosages more quickly and accurately, potentially improving treatment safety and effectiveness.
