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.

Recently, scanning probe microscope (SPM) has become a promising technique for nanofabrication. In this paper, we present a novel method of nano-fabrication, namely, nano-fabrication by atomic force microscope (AFM) tips under laser irradiation. The SPM was operated as an AFM. During imaging and nano-fabrication, the AFM is in constant force mode. The tip is fixed with the sample moving via a tube scanner. Nano-lithography software controls the scanner motion in x and y directions. The SPM has an open architecture allowing an external laser beam incident on the tip at an incident angle between 0 to 45 • . A vertically-polarized Nd:YAG pulsed laser with a pulse duration of 7 ns was focused on the tip. An electrical shutter was introduced to switch the laser irradiation. Alignment between the laser beam and the tip was performed under a high-power charge coupled device (CCD) microscope. The kinetics of the nanostructure fabrication has been studied. Craters were created in air ambient under different laser pulse numbers, pulse energies and tip force. The feature size of the craters, which are in the nanometer scale, increases with the pulse number, pulse energy and the tip force. This technique has potential applications in nano-lithography and high-density data storage.

In this work, Al-doped MnO (Al-MO) nanoparticles have been synthesized by a simple chemical method with the aim to enhance cycling stability. At room temperature and 50 °C, the specific capacitances of Al-MO are well-maintained after 10 000 cycles. Compared with pure MnO nanospheres (180.6 F g at 1 A g), Al-MO also delivers an enhanced specific capacitance of 264.6 F g at 1 A g. During the cycling test, Al-MO exhibited relatively stable structure initially and transformed to needlelike structures finally both at room temperature and high temperature. In order to reveal the morphology evolution process, in situ NMR under high magnetic field has been carried out to probe the dynamics of structural properties. The Na spectra and the SEM observation suggest that the morphology evolution may follow pulverization/reassembling process. The Na intercalation/deintercalation induced pulverization, leading to the formation of tiny MnO nanoparticles. After that, the pulverized tiny nanoparticles reassembled into new structures. In Al-MO electrodes, doping of Al could slow down this structure evolution process, resulting in a better electrochemical stability. This work deepens the understanding on the structural changes in faradic reaction of pseudocapacitive materials. It is also important for the practical applications of MnO-based supercapacitors.

Mechanical strength is crucial to flexible supercapacitors during their practical usage. In this work, polybenzimidazole with a high tensile strength of ∼100 MPa, an anion (or proton) conducting polymer electrolyte when doped with KOH (or H 3 PO 4 ), was employed to fabricate highly robust and flexible supercapacitors. The polybenzimidazole film was integrated with activated carbon electrodes coated on graphite paper. These flexible supercapacitors exhibited low equivalent series resistance and good cycling stability of capacitance retention above 90% after 10000 cycles. Under mechanical deformations of bending, twisting, and rolling as well as a repeated bending test, the electrochemical performance of the flexible supercapacitors was well maintained, demonstrating good flexibility. The integration design showed better reliability against mechanical damage. It is an advantage for flexible supercapacitors with high energy density in mass production especially for devices based on KOH doped polybenzimidazole. This work suggests that polybenzimidazole based ion conducting polymer electrolytes are very promising for developing highly robust flexible supercapacitors in future practical applications.

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