We developed a microfluidic chip, called the heat-responsive microchanne
l chip, that showed a positive correlation between sperm activity and tem
perature. Expanding on this discovery, we created a novel high-throughpu
t sperm sorting chip that combines thermotaxis behavior and upstream s
wimming.
Sperm with thermosensitivity, which can sense temperature gradients as s
mall as 0.014°C/mm and temperature differences as low as 0.0006°C, are r
eferred to as "thermosensitive sperm." We utilized this characteristic to de
velop a microfluidic chip that efficiently sorts sperm using their upstream
behavior and thermotaxis. Traditional upstream sorting methods struggle
with suboptimal recovery rates due to random swimming patterns. To ove
rcome this, we integrated a constant temperature heating system on the c
hip, ensuring a stable temperature difference from top to bottom. Sperm
's inclination to swim towards higher temperatures guides active sperm
below the chip to swim upstream and be collected. To prevent post-sortin
g mixing, we included a porous polycarbonate membrane (PCTE) to separ
ate the upper layer of healthy sperm from the lower layer of raw semen, e
nsuring the purity of the sorted sample.
To evaluate the performance of our high-throughput sperm sorting chip,
we analyzed processed semen samples using OpenCASA, an ImageJ tool.
We calculated sperm motion parameters, motility, and recovery rates of a
ctive sperm. Our results demonstrated successful sorting of millions of hig
h-quality sperm, meeting the World Health Organization's standards for
excellent sperm quality in assisted reproductive technologies.
Compared to previous microfluidic chips, our technology offers several ad
vantages. It eliminates the need for complex pre-processing steps, reduce
s sorting time, minimizes sperm damage, improves throughput, and yield