Wearable wireless sensing systems capable of monitoring critical biomarkers are increasingly valued for health monitoring and disease management. However, current systems often compromise on sensitivity, multi-parameter sensing capacity, compactness, power consumption, and wearing comfort, limiting their skin-interfaced applications. Here, we present a wireless, battery-free, multiplexed sensing system based on a high-order exceptional point (EP)—a singularity in non-Hermitian realm. This system features multiple distinct resonance frequencies that sensitively respond to physiological variations, exhibiting over 10-fold sensitivity improvement and 50% size reduction compared to conventional resonator-based systems. Moreover, the sensor employs a strain-resilient liquid metal composite and a soft substrate, ensuring wearing comfort, mechanical reliability, and antimicrobial properties. The effectiveness of this system is demonstrated through in situ monitoring of skin temperature and sweat electrolytes during exercise and prolonged monitoring of sweat glucose and ammonium in different subjects. The proposed system is highly transformative, offering benefits for various wearable applications.

The accurate monitoring of vital physiological parameters, exemplified by heart rate, respiratory rate, and intracranial pressure (ICP), is of paramount importance, particularly for managing severe cranial injuries. Despite the rapid development of implantable ICP sensing systems over the past decades, they still suffer from, for example, wire connection, low sensitivity, poor resolution, and the inability to monitor multiple variables simultaneously. Here, we propose an ultrasensitive multimodal biotelemetric system that amalgamates an iontronic pressure transducer with exceptional point (EP) operation for the monitoring of ICP signals. The proposed system can exhibit extraordinary performance regarding the detection of minuscule ICP fluctuation, demonstrated by the sensitivity of 115.95 kHz/mmHg and the sensing resolution down to 0.003 mmHg. Our system excels not only in the accurate quantification of ICP levels but also in distinguishing respiration and cardiac activities from ICP signals, thereby achieving the multimodal monitoring of ICP, respiratory, and heart rates within a single system. Our work may provide a pragmatic avenue for the real-time wireless monitoring of ICP and thus hold great potential to be extended to the monitoring of other vital physiological indicators.

Physically unclonable functions (PUFs) are a class of hardware-specific security primitives based on secret keys extracted from integrated circuits, which can protect important information against cyberattacks and reverse engineering. Here, we put forward an emerging type of PUF in the electromagnetic domain by virtue of the self-dual absorber-emitter singularity that uniquely exists in the non-Hermitian parity-time ( PT )–symmetric structures. At this self-dual singular point, the reconfigurable emissive and absorptive properties with order-of-magnitude differences in scattered power can respond sensitively to admittance or phase perturbations caused by, for example, manufacturing imperfectness. Consequently, the entropy sourced from inevitable manufacturing variations can be amplified, yielding excellent PUF security metrics in terms of randomness and uniqueness. We show that this electromagnetic PUF can be robust against machine learning–assisted attacks based on the Fourier regression and generative adversarial network. Moreover, the proposed PUF concept is wavelength-scalable in radio frequency, terahertz, infrared, and optical systems, paving a promising avenue toward applications of cryptography and encryption.

Modern wireless implantable medical devices face escalating demand for lightweight and low-cost wireless solutions exploited to wake up sensors and transfer data. In this paper, we propose and experimentally demonstrate the efficient, multi-band wireless power transfer (WPT) systems that are symmetric with respect to the combined parity ( P ) and time reversal ( T ) transformations (i.e., space-time reflection symmetry). In analogy with non-Hermitian PT -symmetric physical systems that can have branching real eigenfrequencies as a function of the dimensionless non-Hermiticity and the coupling factor, the PT -symmetric WPT system exhibits multi-band and/or wideband operations via adjustment of the non-Hermiticity (i.e., quality-factor of resonant tanks) and their mutual inductive or capacitive coupling strength. Here, we put forward design and implementation for achieving dual-band, tri-band, and wideband PT -symmetric WPT systems, capable of operating in the industrial, scientific, and medical (ISM) bands (27.12 MHz and 40.68 MHz) with high transmission efficiency. This compact and low-cost WPT technique may be exploited in many practical applications, such as wireless charging of bioimplants and wearables, as well as interrogation of battery-free medical devices and internet-of-things (IoT) sensors to assist smart healthcare.

In recent decades, thriving Internet of Things (IoT) technology has had a profound impact on people’s lifestyles through extensive information interaction between humans and intelligent devices. One promising application of IoT is the continuous, real-time monitoring and analysis of body or environmental information by devices worn on or implanted inside the body. This research area, commonly referred to as wearable electronics or wearables, represents a new and rapidly expanding interdisciplinary field. Wearable electronics are devices with specific electronic functions that must be flexible and stretchable. Various novel materials have been proposed in recent years to meet the technical challenges posed by this field, which exhibit significant potential for use in different wearable applications. This article reviews recent progress in the development of emerging nanomaterial-based wearable electronics, with a specific focus on their flexible substrates, conductors, and transducers. Additionally, we discuss the current state-of-the-art applications of nanomaterial-based wearable electronics and provide an outlook on future research directions in this field.