Recent progress of morphable 3D mesostructures in advanced materials

Soft robots complement the existing efforts of miniaturizing conventional,rigid robots,and have the potential to revolutionize areas such as military equipment and biomedical devices.This type of system can accomplish tasks in complex and time-varying environments through geometric reconfiguration induced by diverse external stimuli,such as heat,solvent,light,electric field,magnetic field,and mechanical field.Approaches to achieve reconfigurable mesostructures are essential to the design and fabrication of soft robots.Existing studies mainly focus on four key aspects:reconfiguration mechanisms,fabrication schemes,deformation control principles,and practical applications.This review presents a detailed survey of methodologies for morphable mesostructures triggered by a wide range of stimuli,with a number of impressive examples,demonstrating high degrees of deformation complexities and varied multi-functionalities.The latest progress based on the development of new materials and unique design concepts is highlighted.An outlook on the remaining challenges and open opportunities is provided.

Continuously Quantifying Oral Chemicals Based on Flexible Hybrid Electronics for Clinical Diagnosis and Pathogenetic Study

Simultaneous monitoring of diverse salivary parameters can reveal underlying mechanisms of intraoral biological processes and offer profound insights into the evolution of oral diseases.However,conventional analytical devices with bulky volumes,rigid formats,and discrete sensing mechanisms deviate from the requirements of continuous biophysiological quantification,resulting in huge difficulty in precise clinical diagnosis and pathogenetic study.Here,we present a flexible hybrid electronic system integrated with functional nanomaterials to continuously sense Ca^(2+),pH,and temperature for wireless real-time oral health monitoring.The miniaturized system with an island-bridge structure that is designed specifically to fit the teeth is only 0.4g in weight and 31.5×8.5×1.35 mm^(3) in dimension,allowing effective integration with customized dental braces and comfort attachment on teeth.Characterization results indicate high sensitivities of 30.3 and 60.6 mV/decade for Ca^(2+)and pH with low potential drifts.The system has been applied in clinical studies to conduct Ca^(2+)and pH mappings on carious teeth,biophysiological monitoring for up to 12 h,and outcome evaluation of dental restoration,providing quantitative data to assist in the diagnosis and understanding of oral diseases.Notably,caries risk assessment of 1o human subjects using the flexible system validates the important role of saliva buffering capacity in caries pathogenesis.The proposed flexible system may offer an open platform to carry diverse components to support both clinical diagnosis and treatment as well as fundamental researchfororaldiseases and induced systemicdiseases.

Subsurface damage and bending strength analysis for ultra-thin and flexible silicon chips

Subsurface damage(SSD) is an unavoidable problem in the precision mechanical grinding for preparing ultra-thin and flexible silicon chips. At present, there are relatively few studies on the relationship between SSD and the bending strength of ultra-thin chips under different grinding parameters. In this study, SSD including amorphization and dislocation is observed using a transmission electron microscope. Theoretical predictions of the SSD depth induced by different processing parameters are in good agreement with experimental data. The main reasons for SSD depth increase include the increase of grit size, the acceleration of feed rate, and the slowdown of wheel rotation speed. Three-point bending test is adopted to measure the bending strength of ultra-thin chips processed by different grinding conditions. The results show that increasing wheel rotation speed and decreasing grit size and feed rate will improve the bending strength of chips, due to the reduction of SSD depth. Wet etching and chemical mechanical polishing(CMP) are applied respectively to remove the SSD induced by grinding, and both contribute to providing a higher bending strength, but in comparison, CMP works better due to a smooth surface profile. This research aims to provide some guidance for optimizing the grinding process and fabricating ultra-thin chips with higher bending strength.