Fig 1.
Scheme of EWOD chip design and fabrication and principle of EWOD.
A. Description of EWOD chip fabrication and bottom plate of EWOD chips (white scale bar, 6 mm). B. EWOD is based on the variation of the wettability of liquids on a dielectric solid surface on altering the electric potential. The contact angle of the liquid is decreased from its initial contact angle when a voltage is applied. On releasing the electric potential, the contact angle of the liquid reverts to the initial contact angle. C. Scheme of droplet transport.
Fig 2.
Operating the EWOD system for in vitro culture of embryo.
A. Manipulating a droplet moving with an EWOD system. (a) The EWOD chip was placed in an incubator (b) Before motion, the droplet time = 0 s (c) The upper droplet moved 1.5 mm, right, time = 5 s (d) The lower droplet moved 1.5 mm, left, time = 10 s. B. Applied voltage versus velocity of droplets moving in air and in an oil-bath environment. C. Static embryo culture on a Petri dish and in an EWOD chip. The development of embryos in a EWOD chip was recorded as compatible relative to a traditional culture dish as control. D. Observation of an embryo in a moving droplet. Sequence images of embryo movement in a dynamic EWOD chip culture (a) before applied voltage. (b) The shape of droplet was altered with an applied voltage at the first electrode (c) The embryo was moving to the first electrode (d) The embryo stopped near the medium-oil interface (e) The embryo was moving rapidly when a applied voltage to the second electrode (f) The embryo was stopped near the medium-oil interface of the second electrode. *E day, the date after mating. Black arrow bar, 100 μm.
Fig 3.
Dynamic embryo culture in EWOD chips.
Embryo culture development on the EWOD system, The upper panel is static culture on the EWOD chip: from 4-cell stage to expanded blastocyst stage; The middle and lower panels are dynamic culture with different velocity of droplets: from 4 or 8-cell stage, early blastocyst stage to hatching blastocyst stage. The embryo development in dynamic culture with the droplet velocity (15 sec /0.5 hr) was hatching earlier in comparison to the embryo in static culture. *E day, the date after mating. Black arrow bar, 100 μm.
Fig 4.
The embryo development and blastocyst quality of dynamic culture on EWOD chip.
A. The statistics result of blastocyst development in EWOD dynamic culture (n = 18) in comparison to static culture (n = 38). Most embryos were successfully cleaved to a blastocyst stage. B. The blastocysts collected on day 3 (E4.5) is further classified according the morphology grading. A significantly higher rate of hatching blastocyst was demonstrated in dynamic culture in comparison to static culture (p = 0.028). *, Chi-square test, p<0.05. Values are mean ±standard error of measurements.
Fig 5.
Embryo transfer from EWOD embryos to pseudo-pregnant female mice.
Panel A, Preparation of recipient mice for embryo transfer. Panel B, Pups was born after transfer of embryo cultured from EWOD. The recipients were allowed to deliver and raise pups.