Formation of colloids or gels within droplets

A method, comprising:

• transporting a first fluid containing a gel precursor at at least 0.5 vol % into a microfluidic droplet containing a second fluid;
• and
• causing the gel precursor to solidify to form a gel particle contained within the second fluid in the microfluidic droplet,
• wherein the first fluid is contained within a first microfluidic channel, the microfluidic droplet is contained within a second microfluidic channel intersecting the first microfluidic channel, and transport of the first fluid into the microfluidic droplet occurs at an intersection between the first microfluidic channel and the second microfluidic channel, and
• wherein the intersection is a T intersection, the first microfluidic channel ending at the intersection and the second microfluidic channel passing through the intersection.

A method, comprising:

• transporting a first fluid containing a gel precursor at at least 0.5 vol % into a microfluidic droplet containing a second fluid;
• and
• causing the gel precursor to solidify to form a gel particle contained within the second fluid in the microfluidic droplet,
• wherein the first fluid is contained within a first microfluidic channel, the microfluidic droplet is contained within a second microfluidic channel intersecting the first microfluidic channel, and transport of the first fluid into the microfluidic droplet occurs at an intersection between the first microfluidic channel and the second microfluidic channel, and
• wherein the second microfluidic channel connects to the intersection via an orifice having an area of no more than 50% of the average cross-sectional dimension of the second microfluidic channel.