Droplets and Gravity: A Smart Way to Handle Tiny Liquids

In the world of tiny tech, handling droplets is a big deal. Imagine trying to move and split tiny drops of liquid with precision. That's what digital microfluidic devices do. They use something called electrowetting on dielectric (EWOD) to control droplets. But there's a problem. The way droplets split is limited by the shape of the electrodes. Scientists have come up with a clever solution. They use gravity to help split droplets. This method, called gravity-induced size-tuning splitting (GITS), doesn't need special electrodes or complicated setups. Both experiments and computer simulations showed that gravity helps in creating droplets by making the EWOD force stronger in a specific direction.The size of the droplets can be adjusted. It depends on things like the droplet's volume, the voltage used, and the contact line ratios between the droplet and the electrodes. To make sure the droplets behave reliably, scientists studied the critical size for passive dropping. They found that this size changes with the gap height. The GITS method was made even smarter. It uses artificial intelligence (AI) to control the contact line and the gravity-induced droplet dropping. This combination achieved a wide range of splitting ratios, from 1 to 7. 33, with high precision. Finally, the GITS method was used to handle reagents of different sizes for cell viability assays. This shows its potential for flexible reagent configuration in future biomedical applications.