Deterministic bead-in-droplet ejection utilizing an integrated plug-in bead dispenser for single bead–based applications

Abstract

This paper presents a deterministic bead-in-droplet ejection (BIDE) technique that regulates the precise distribution of microbeads in an ejected droplet. The deterministic BIDE was realized through the effective integration of a microfluidic single-particle handling technique with a liquid dispensing system. The integrated bead dispenser facilitates the transfer of the desired number of beads into a dispensing volume and the on-demand ejection of bead-encapsulated droplets. Single bead–encapsulated droplets were ejected every 3 s without any failure. Multiple-bead dispensing with deterministic control of the number of beads was demonstrated to emphasize the originality and quality of the proposed dispensing technique. The dispenser was mounted using a plug-socket type connection, and the dispensing process was completely automated using a programmed sequence without any microscopic observation. To demonstrate a potential application of the technique, bead-based streptavidin–biotin binding assay in an evaporating droplet was conducted using ultralow numbers of beads. The results evidenced the number of beads in the droplet crucially influences the reliability of the assay. Therefore, the proposed deterministic bead-in-droplet technology can be utilized to deliver desired beads onto a reaction site, particularly to reliably and efficiently enrich and detect target biomolecules.

Modelling on the droplet formation and optimizing of the microfluidic cartridge used for the microfluidic impact printing

“…Streule et al reported a device, named single-cell-manipulator (SCM), with a separable piezo-stack actuator [14]. Choi et al [15] and Kim et al [16] developed a novel nanoliter liquid dispensing system with plug-and-play dispensers and detachable pneumatic pump. Furthermore, Bsoul et al presented a disposable ink-jet dispenser technology and demonstrated a Lab-on-a-printer concept through using an ink-jet dispenser and a microfluidic mixer [17].…”

“…Furthermore, a multiplexed, scalable, and compact microfluidic multi-parametric gradient generation system based on MIP was developed for multi-dimensional studies of synthetic genetic modules in cell-free system [19]. Different from those of previously mentioned nano-liter dispensing technologies [15][16][17], the refill of liquid in the MIP system is conducted automatically by the combined effect of capillary force in the microchannel and negative pressure generated by the membrane's deformation restoration, which means it does not need any additional input from an external pump or potential energy. With the design of microfluidic channel and nozzle, the minimum loading volume and dead volume of the MIP system are as low as 2 μl and 0.25 μl, respectively [19].…”

Microfluidic Production of Autofluorescent BSA Hydrogel Microspheres and Their Sequential Trapping for Fluorescence-Based On-Chip Permanganate Sensing

“…It enables placing the microparticles one by one into an arbitrary location simply on the basis of flow resistance [ 11 ]. Until now, this method has been widely used to immobilize droplets or cells, meaning that it would be beneficial to a variety of applications [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ]. Taking this into account, it is conceivable that, in combination with the hydrodynamic trapping technique, developing new microscale fluorescent materials or microscale carriers for encapsulating conventional fluorescent reagents should be a key to addressing the problem of the dimensional gap.…”

Multiplex Analysis on a Single Porous Hydrogel Bead with Encoded SERS Nanotags

“…Bead-based assays have been widely used in disease diagnostic, biological, and chemical analysis because of their high flexibility in usage. − For example, they can be integrated with microfluidic chips, optical fibers, microwells, and tips. − The surface of bead can be easily functionalized with various biorecognition receptors, such as antibody, molecular imprint, aptamer, and peptide. Therefore, the bead can act as solid phase carrier in assays or sensors. , Compared with a conventional planar carrier like microwell or microarray commonly used in ELISA (enzyme-linked immunosorbent assay), the bead with high surface area to volume ratio (SVR) can be effectively mixed with samples by vortex, which leads to higher sensitivity and shorter reaction time. , In addition, over the past decades, many considerable encoding techniques have been developed, and the beads with unique codes can form suspension array, by which high-throughput and multiplex assays with faster detection and less sample are realized. However, an encoded single bead only bears one kind of molecular probe on its surface, posing a challenge for further sample reduction and higher throughput.…”

“…Therefore, the bead can act as solid phase carrier in assays or sensors. 8,9 Compared with a conventional planar carrier like microwell or microarray commonly used in ELISA (enzyme-linked immunosorbent assay), the bead with high surface area to volume ratio (SVR) can be effectively mixed with samples by vortex, which leads to higher sensitivity and shorter reaction time. 10,11 In addition, over the past decades, many considerable encoding techniques have been developed, and the beads with unique codes can form suspension array, by which high-throughput and multiplex assays with faster detection and less sample are realized.…”