Question

this movement triggers mechanical gears in the brace to turn. then, a small generator converts the energy from the moving gears into electricity. the electricity is collected and stored in a battery, which the hiker can use to charge her phone. someday soon, engineers hope to adapt this technology for use in other areas. what does the phrase this technology refer to? chargeable batteries wearable energy harvesters stronger knee braces smaller generators someday soon, engineers hope to adapt? for use in other areas.

Explanation:

The text describes a knee - brace that harvests energy from movement. This is a type of wearable energy harvester. The technology being referred to is the concept of wearable energy harvesters.

Answer:

wearable energy harvesters