An affordable droplet-based flow analyzer incorporating peristaltic micro-pumps has been developed for fluorescent ammonium sensing. The cost-effective peristaltic micro-pumps, modified using 3D-printing techniques, feature a 3D-printed pump base integrated with a Hall sensor to monitor the rotation of the pump motor. This setup generates a pulse flow instead of a continuous flow, delivering specific volumes (typically between 3 to 4 μL) of solution with each rotation. By using separate pumps to deliver the aqueous and oil phases, these phases merge to form a droplet flowing stream. The relative standard deviation (RSD) values for droplet volumes range from 3.97 % to 5.99 % ( n =50) across different pumps. The analyzer utilizes a reaction between ammonium, ortho-phthalaldehyde, and sulfite to produce a fluorescent derivative, allowing for sensitive detection of low ammonium concentrations. A custom light-emitting diode (LED)-based fluorescence detector has been fabricated using 3D printing, ensuring cost-effective production. The analyzer provides a limit of detection of 0.02 μM (3 σ ) and an RSD of 0.15 % ( n =10, 1 μM ammonium). This analyzer offers several practical advantages, including reduced reagent consumption and the potential for further development in distributed on-site analysis. The use of 3D printing facilitates rapid prototyping and customization, making the system adaptable to various analytical applications.
The development of sensors for the detection of albumin concentrations in urine is essential for the long-term detection and treatment of kidney disease. Albumin is an important biomarker for kidney diseases. However, albumin concentrations in patient urine are often too high (more than 0.15 mg/mL), causing competitive lateral flow immunoassays to exceed detection ranges. In this work, we report for the first time a one-step, fluorescent lateral-flow quantification of human urine albumin using an in-situ minipump and clinical evaluation in renal patients, eliminating the need for external sample dilution. The device is constructed by integrating a lateral flow immunoassay strip and an in-situ minipump that sits above the sample/conjugate pad of the strip. The detection is based on competitive immunoassay by using fluorescent nanoparticles as the probe, and the in-situ pump performs on-chip dilution. The linear detection range with this device is 0.1-10 mg/mL for a 1000-fold dilution of the sample with the pump, and 1-100 mg/mL for a 10,000-fold dilution. The device can be used for the direct quantification of albumin in the urine of patients with clinical kidney disease. We anticipate the work can open up exciting new opportunities for the quantification of protein biomarkers, and their wide range of applications in clinical and home-settings.
Haiyuan Yuan,Zupeng Liu,Jundong Song,Soichiro Okamura,John H. Xin,Ming Xue,Titao Jing
Stretchable materials are the foundation of dielectric actuators (DEAs) for artificial muscle. However, the inadequate dielectric constant of stretchable materials has always greatly limited the performance of artificial muscle. Recently, soft fillers have been proposed to improve the dielectric property and preserve the stretchability for softness, aiming to avoid the stiffening effect of traditional rigid fillers. As composites, an amount of interfacial region is generated, which remarkably affects composites’ performance from dielectrics to mechanics. Herein, we demonstrate that the size effect, interfacial binding, and compatibility have a great impact on soft filler doped composites. Particularly, according to the liquid characteristics of soft fillers, we explore an interfacial modification method using surfactants. Composite breakdown strength is thus enhanced 2.2-fold from that in the control group due to the reduction of mismatch between fillers and matrix. Moreover, surfactants alleviate the well-known stiffening effect in small fillers. The area strain of the composites reaches 10.3 ± 0.4% at a low electric field of 7 MV/m, and a soft micropump is successfully assembled. These findings demonstrate a unique and combined interfacial influence of soft filler doped elastomer, which promotes the advancements of the dielectric elastomer artificial muscle.
危险品化学品经营许可证（带存储）