Droplet
microfluidics provides powerful tools for biochemical applications.
However, precise fluid control is usually required in the process
of droplet generation and detection, which hinders droplet-based applications
in point-of-care testing (POCT). Here, we present a droplet reinjection
method capable of droplet distribution without precise fluid control
and external pumps by which the droplets can be passively aligned
and detected one by one at intervals. By further integrating the surface-wetting-based
droplet generation chip, an integrated POrtable Droplet system (iPODs)
is developed. The iPODs integrates multiple functions such as droplet
generation, online reaction, and serial reading. Using the iPODs,
monodisperse droplets can be generated at a flow rate of 800 Hz with
a narrow size distribution (CV <2.2%). Droplets are kept stable,
and the fluorescence signal can be significantly identified after
the reaction. The spaced droplet efficiency in the reinjection chip
is nearly 100%. In addition, we validate digital loop-mediated isothermal
amplification (dLAMP) within 80 min with a simple operation workflow.
The results show that iPODs has good linearity (R
2 = 0.999) at concentrations ranging from 101 to 104 copies/μL. Thus, the developed iPODs highlights
its potential to be a portable, low-cost, and easy-to-deploy toolbox
for droplet-based applications.