Bioinspired design of highly sensitive flexible tactile sensors for wearable healthcare monitoring

The design of microscale architectures integrated with low-dimensional nanomaterials for tactile sensors has attracted considerable attention owing to their high performance for various potential applications, especially in the field of healthcare monitoring. However, there still remains a critical challenge to achieve high sensitivity in response to different magnitude external pressure. Herein, we introduce a high performance capacitive tactile sensor based on Silver nanowires coated biomimetic hierarchical array architecture, which consists of mini-domes by the way of vacuum adsorption from through-hole arrays and micro-cones by duplicating Calathea zebrina leaf, respectively. This hybrid graded microstructure as electrode exhibits remarkably improved sensitivity and stimulus responding range when compared with the other monotonous counterparts. Moreover, an optimized ionic gel film with remarkable interfacial capacitance is sandwiched by microstructured electrodes as the dielectric layer, further boosting the performance of the tactile sensor. As a result, the obtained sensor demonstrates a board detection range from 24 Pa to 90 kPa with a maximum sensitivity of 37.8 kPa^?1, and a fast response time (<78 ms). These superior performances of our tactile sensor lay a foundation for various applications in healthcare monitoring. It can not only sense and distinguish subtle arterial pulse signals even under different ages, genders and states of motion but also monitor physiological activity with large pressure as well, such as breathing, plantar pressure, and so on. We envision this bionic tactile sensor holds great potential in wearable electronics.     

A strategy for improving the sensitivity of molecularly imprinted electrochemical sensors based on catalytic copper deposition

A novel method to improve the sensitivity of molecularly imprinted polymer sensors was developed. Oxytetracycline (OTC), which was selected as the template molecule, was first rebound to the imprinted cavities. Gold nanoparticles were then labeled with the amino groups of OTC molecules via electrostatic adsorption and non-covalent interactions. Copper ions were catalytically reduced by the gold nanoparticles, and copper was deposited onto the electrode. The deposited copper was electrochemically dissolved, and its oxidative currents were recorded by differential pulse voltammetry (DPV). OTC could be determined indirectly within the concentration range of 3.0 × 10⁻¹⁰ to 1.5 × 10⁻⁷ mol L⁻¹ with a detection limit of 6.8 × 10⁻¹¹ mol L⁻¹.     

Application of an Hg selective imprinted polymer as a new modifying agent for the preparation of a novel highly selective and sensitive electrochemical sensor for the determination of ultratrace mercury ions

A simple and very selective electrode, based on a mercury ion imprinted polymer (IIP), and its application for the determination of Hg²⁺ ions in the real samples is introduced. Mercury ion selective cavities were created in the vinyl pyridine based cross-linked polymer. In order to fabricate the sensor carbon particles and polymer powder were mixed with melted n-eicosane. An explicit difference was observed between the responses of the electrodes modified with IIP and non imprinted polymer (NIP), indicating proper performance of the recognition sites of the IIP. Various factors, known to affect the response behavior of selective electrode, were investigated and optimized. The interference of different ionic species with the response of the electrode was also studied. The results revealed that, compared to previously developed mercury selective sensors, the proposed sensor was more selective, regarding the common potential interferer. This sensor showed a linear response range of 2.5 × 10⁻⁹–5.0 × 10⁻⁷ M and lower detection limit of 5.2 × 10⁻¹⁰ M (S/N). The sensor was successfully applied to the determination of mercury in real samples.