The influence of solution pH, analyte concentration and in-source dissociation on the measurement of the association constant for a single chain variable fragment of a monoclonal antibody (scFv) and its native trisaccharide ligand by nanoelectrospray-Fourier transform ion cyclotron resonance mass spectrometery has been systematically investigated. From the results of this study, experimental conditions that preserve the original distribution of bound and unbound protein in solution into the gas phase, such that the nanoES mass spectrum provides a quantitative measure of the solution composition, were identified. These include the use of short spray durations (<10 min) to minimize pH changes, equimolar concentrations of protein and ligand to minimize the formation of nonspecific complexes, and short accumulation times (<2 s) in the hexapole of the ion source to avoid collisional heating and dissociation of the gaseous complex. Application of this methodology to the scFv and a series of carbohydrate ligands yields results that are in agreement with values previously determined by isothermal titration calorimetry. Competitive binding experiments performed on solutions containing the scFv and a mixture of carbohydrate ligands were also found to yield accurate association constants.

Flexible pulse sensors that can detect subtle skin surface deformation caused by arterial pulses are key components for developing non‐invasive continuous pulse waveform monitoring systems that provide vital health status parameters. Piezoelectric pulse sensors (PPSs) offer a promising solution for flexible pulse sensors due to their relatively high sensitivity and stability, and low power consumption, when compared with conventional active pulse sensors. However, the reported high‐performance PPSs contain toxic lead, which limits their practical applications. In this study, a highly sensitive and flexible PPS that detects surface deflections on the micrometer scale is fabricated with single‐crystalline group III‐nitride thin film. This biocompatible flexible PPS is sensitive enough to detect pulse waveform with detailed characteristic peaks from most arterial pulse sites when attached to the skin surface without applying external pressure. Useful physiological parameters such as the pulse rate, artery augmentation index, and pulse wave velocity can be drawn from the as‐acquired pulse waveforms. The flexible PPS can also be used to continuously monitor the arterial pulse waveform.

Accurate and continuous monitoring of eye movements using compact, low‐power‐consuming, and easily‐wearable sensors is necessary in personal and public health and safety, selected medical diagnosis techniques (point‐of‐care diagnostics), and personal entertainment systems. In this study, a highly sensitive, noninvasive, and skin‐attachable sensor made of a stable flexible piezoelectric thin film that is also free of hazardous elements to overcome the limitations of current computer‐vision‐based eye‐tracking systems and piezoelectric strain sensors is developed. The sensor fabricated from single‐crystalline III‐N thin film by a layer‐transfer technique is highly sensitive and can detect subtle movements of the eye. The flexible eye movement sensor converts the mechanical deformation (skin deflection by eye blinking and eyeball motion) with various frequencies and levels into electrical outputs. The sensor can detect abnormal eye flickering and conditions caused by fatigue and drowsiness, including overlong closure, hasty eye blinking, and half‐closed eyes. The abnormal eyeball motions, which may be the sign of several brain‐related diseases, can also be measured, as the sensor generates discernable output voltages from the direction of eyeball movements. This study provides a practical solution for continuous sensing of human eye blinking and eyeball motion as a critical part of personal healthcare, safety, and entertainment systems.

Flexible piezoresistive sensors with high sensitivity, low cost, and wide response ranges are urgently required due to the rapid development of wearable electronics. Here, carbon nanotubes (CNTs)/graphene/waterborne polyurethane (WPU)/cellulose nanocrystal (CNC) composite aerogels (CNTs/graphene/WC) were fabricated by facile solution mixing and freeze-drying technology for high-performance pressure sensors. WPU and CNC were constructed as a 3D structure skeleton, and the synergistic effect of CNTs and graphene was beneficial to enhancing the sensing performance. The obtained pressure sensor exhibits a highly porous network structure, remarkable mechanical properties (76.16 kPa), high sensitivity (0.25 kPa–1), an ultralow detection limit (0.112 kPa), and high stability (>800 cycles). More importantly, the piezoresistive sensor could be successfully used to detect various human motions such as finger bending, squatting–rising, walking, and running and effectively extract real-time information by the electrical signals. In addition, the CNTs/graphene/WC composite aerogel exhibits excellent thermal insulation performance, which can withstand 160 °C for a long time without any damage to the structure. The CNTs/graphene/WC composite aerogel, because of its thermal insulation property, endows the sensor with the potential for application in high-temperature environments. The results indicate that CNTs/graphene/WC composite aerogels possess high sensing performance and outstanding thermal insulation, which means that the aerogels could be used as flexible, wearable electronics.