The correct answer is Pyro-electrodynamics.

- In microfluidics, the contactless manipulation of liquids using electric fields is a critical technique for precise fluid control without direct physical interaction.

- Electrowetting involves changing the wettability of a surface by applying an electric potential, but it requires direct contact with the liquid and surface.
- Magnetophoresis manipulates particles or fluids using magnetic fields, not electric fields.
- Dielectrophoresis exerts forces on polarizable particles within non-uniform electric fields but typically acts on particles suspended in liquids, not the bulk fluid itself.
- Pyro-electrodynamics, however, utilizes electric fields generated by temperature-induced charges on pyro-electric materials to move and manipulate liquid droplets without direct contact. This method exploits the pyro-electric effect to induce electric fields that can move liquids in a contactless manner, making it uniquely suited for applications where contamination-free handling is essential.

Thus, Pyro-electrodynamics is the technique that enables contactless liquid manipulation through electric fields in microfluidics.

Reference: Microfluidics and Nanofluidics Handbook, Volume 1, Chapter 4, pp. 113-135