Wearable biosensors with skin interfaces for newborn and neonatal health monitoring

In a recent review published in Communications Materials, researchers reviewed recent improvements in newborn wearable systems, concentrating on skin-interfaced wearables for physiological monitoring across many branches.

Study: Skin-interfacing wearable biosensors for smart health monitoring of infants and neonates. Image Credit: Gorodenkoff/Shutterstock.com

Background

Health evaluations of baby patients in critical care could be particularly difficult for patients and their caregivers since testing settings entail several catheters, probes, and electrodes that restrict patient movement.

Health assessments generally require expensive and cumbersome instruments to monitor physiological parameters such as respiration rate, heart rate, blood oxygen saturation, temperature, ion concentrations, and blood pressure.

However, over the last several decades, scientific advances have driven toward wearable, non-invasive, and soft technology to eclipse present procedures.

About the review

In the present review, researchers explored the material foundation for wearable devices, focusing on the concepts and technical improvements of key physiological monitoring branches such as biopotential, optical, temperature, electrochemical, and multi-signal sensing.

Material development for wearable sensors

Epidermal electronic systems (EES) are soft, flexible electronic devices created utilizing microelectromechanical systems (MEMS) technology. These devices have the same material qualities as the epidermis, allowing for high flexibility.

Thin film materials like polyimide and thin metal depositions can be employed as conductive layers, resulting in ultrathin and flexible devices with sub-nanometer bending stiffnesses and a 140 kPa effective modulus.

One can readily apply EES to the skin with a thin adhesive transfer film or wet bandage. Third-phase serpentine connects dynamic movement with the skin, high signal quality, and constant contact with the skin surface.

Elastomers, less expensive than silicon wafer technology, are ideal substrates for integrating soft electronics into EES. Elastomeric encapsulation can be used for hybrid electronic systems, as it combines flexible EES sensor devices, stiff active and passive electronics, wire-free communications, and information processing to provide all-in-one equipment facilitating real-time monitoring.

Textiles are commonly used to incorporate biosignal sensing devices due to their perceived convenience and familiarity. Techniques include weaving electrically conductive fibers, stitching on gold- or silver-coated nylon or polyurethane, and printing electric ink on fibers.

These components are easily attachable to garment items, including onesies, straps, and coats. Textile electrodes integrated into clothing minimize conductive gel and tape requirements but reduce signal quality.

Capacitive and resistive strain responses from conductive fibers can assess physiological parameters such as breathing rate and mobility.

One can transfer data via cable connections or cumbersome wireless transmitters, but antennas could be woven into garments and combined with RFID tags to transfer data in a battery-free and wireless manner.

Wearable sensors used to monitor physiological conditions

Human bodies create action potentials through chemical processes monitored by electrodes on the skin. These biopotential signals are critical to monitor health, such as electrocardiograms (ECGs) for cardiac activity, electromyography (EMG) to activate muscles, electroencephalograms (EEGs) for brain activities, and EEGs to track eye movement.

Researchers created an all-in-one EES system to imitate vital sign monitoring in the neonatal intensive care unit (NICU), including wireless inductive power transmission and data exchange to a host reader platform beneath the patient's mattress. The technology is mechanically delicate and requires conductive gel.

EEG is a diagnostic technology that measures brain electrical activity using electrodes implanted in the head. Common modalities include single-channel amplitude-integrated EEG (aEEG) and multichannel continuous EEG (cEEG), with cEEG being the gold standard.

There have been some studies into physically redesigning EEG electrode systems; however, most advancements include developing textile caps or bands to enhance electrode placement while still using typical wet electrodes.

Optical sensing for medical applications uses spectrophotometric principles to noninvasively examine physiological processes transcutaneously.

Researchers have developed a forehead reflectance PPG for preterm newborns, a flexible PPG sensor for the foot, and a wireless system to monitor baby cerebral hemodynamics.

Neonatal non-invasive thin film biomarker sensing, which focuses on sweat, saliva, and urine, can replace standard blood draws in detecting chemical or protein biomarkers for health pre-diagnosis, diagnosis, and prognosis.

Electrochemical sensing detects charge transfer on a sensing electrode, allowing wearables to record current, conductivity, and voltage/potential changes.

Researchers created a multi-signal system that uses binodal ECG and PPG measurement devices to determine pulse arrival time, compute pulse transit time, and measure seismocardiograms.

Conclusions

Based on the review findings, flexible electronics and wearable health monitoring technologies have improved patient outcomes by detecting physiological indicators rather than intrusive treatments.

Advanced signal processing enables medical applications such as blood pressure and body temperature imaging. The downsizing of electronics has resulted in healthcare advances, notably in neonatal applications where small footprints, delicate handling, and simplicity of use are critical.

Wearable stethoscopes for asthma monitoring and wearable dry cEEG for seizure monitoring are recent technologies that have simplified treatment options in the NICU. Automated monitoring systems may especially benefit ill, school-aged children, increasing independence and self-sufficiency.