Machining water through laser cutting of nanoparticle-encased water pancakes.

Due to the inherent disorder and fluidity of water, precise machining of water through laser cutting are challenging. Herein we report a strategy that realizes the laser cutting machining of water through constructing hydrophobic silica nanoparticle-encased water pancakes with sub-millimeter depth. Through theoretical analysis, numerical simulation, and experimental studies, the developed process of nanoparticle-encased water pancake laser cutting and the parameters that affect cutting accuracy are verified and elucidated. We demonstrate that laser-fabricated water patterns can form diverse self-supporting chips (SSCs) with openness, transparency, breathability, liquid morphology, and liquid flow control properties. Applications of laser-fabricated SSCs to various fields, including chemical synthesis, biochemical sensing, liquid metal manipulation, patterned hydrogel synthesis, and drug screening, are also conceptually demonstrated. This work provides a strategy for precisely machining water using laser cutting, addressing existing laser machining challenges and holding significance for widespread fields involving fluid patterning and flow control in biological, chemical, materials and biomedical research.

A Three-Dimensional Paper-Based Isoelectric Focusing Device for Direct Analysis of Proteins in Physiological Samples.

On-site protein analysis is crucial for disease diagnosis in community and family medicine in which microfluidic paper-based analytical devices (µPADs) have attracted growing attention. However, the practical applications of µPADs in protein analysis for physiological samples with high complexity is still limited. Herein, we developed a three-dimensional (3D) paper-based isoelectric focusing (IEF) platform, which is composed of power supply, reservoirs, and separation channel and made by the origami and stacking method, to simultaneously separate and enrich proteins in both low-salt and high-salt samples. Under the optimized experimental conditions, standard proteins (bovine hemoglobin (BHb) and phycocyanin (Phy)) were separated within 18 min under a 36 V power supply and obtained a 10-fold enrichment using the 3D paper-based IEF platform. Then, the capability of the 3D paper-based IEF platform for direct pretreatment of high-salt samples using a 12 V battery as power supply was measured through separating three standard proteins in saline (0.9% NaCl) with separation resolution (SR) > 1.29. Through further coupling with colorimetric and lateral flow strip measurements, the 3D paper-based IEF platform was applied to directly pretreat and quantitatively analyze microalbuminuria and C-reactive proteins in clinical urine and serum samples with analytical results with relative deviations of <8.4% and < 13.1%, respectively, to the clinical test results. This work proposes a new strategy to minimize the difficulty of directly processing high-salt samples with the traditional IEF system and provides a versatile, miniaturized, and low voltage demand analytical platform for on-site analysis of proteins in physiological samples.

Liquid Plasticine Integrated with Isoelectric Focusing for Miniaturized Protein Analysis.

Developing miniaturized and rapid protein analytical platforms is urgently needed for on-site protein analysis, which is important for disease diagnosis and monitoring. Liquid marbles (LMs), a kind of particle-coated droplets, as ideal microreactors have been used in various fields. However, their application as analytical platforms is limited due to the difficulty of pretreating complex samples in simple LMs. Herein, inspired by the microfluidic chip, we propose a strategy through fabricating fluid channels using deformable LM, termed liquid plasticine (LP), to achieve sample pretreatment function. Through combining isoelectric focusing (IEF) with an LP channel, an LP-IEF platform with simultaneous protein separation and concentration functions is realized. The pretreatment capability of the LP-IEF system for proteins in physiological samples is proven using standard proteins and human serum with the results of a clear separation, 10-fold concentration, and a resolution of 0.03 pH. Through cutting the LP after IEF to LMs and transiting isolated LMs containing target proteins for further downstream colorimetric and mass spectrometry measurements, the quantitative analysis of clinical microalbuminuria and identification of α-1-microglobulin/bikunin precursor in clinical diabetic urine samples are achieved. This work proposes a strategy to develop LMs/LPs as a multifunctional integrated analytical platform and the miniaturized LP-IEF device as a rapid protein analytical platform.

Smart Glove Integrated with Tunable MWNTs/PDMS Fibers Made of a One-Step Extrusion Method for Finger Dexterity, Gesture, and Temperature Recognition.

Flexible wearable devices have proven to be emerging tools for motion monitoring, personal healthcare, and rehabilitation training. The development of a multifunctional, flexible sensor and the integration of sensors and a smart chip for signal reading and transmission play a critical role in building a smart wearable device. In this work, a smart glove based on multiwalled carbon nanotubes/poly(dimethylsiloxane) (MWNTs/PDMS) fibers is developed for gesture and temperature recognition. First, the well-tunable, stretchable, and thermal-sensitive MWNTs/PDMS fibers are fabricated via a facile and cost-effective one-step extrusion method. The obtained fibers exhibit an outstanding linear relationship between resistance change and strain in the range of 0-120% and excellent cyclic stability and durability after 20 000 cycles of 50% tension. They also present a linear relationship of resistance change and temperature of 0.55% °C-1 with a correlation coefficient of 0.998 in the range of 0-100 °C. The fibers, as parts of wearable sensors, are then integrated into a smart glove along with a custom-made data acquisition chip to recognize finger dexterity, gestures, and temperature signals and output them through a screen display, an audio system, and Bluetooth transmission. The highly integrated, low-cost, and multifunctional glove holds great potential for various applications, such as sign language recognition, rehabilitation training, and telemedicine in the Internet-of-Things era.