This paper reports the measurement of elastic constants between two DNA strands that are simultaneously hybridized by
a third target-DNA linker. Two probe-DNA strands that are immobilized on fluorescent beads and a target-DNA linker
formed a hybridized assembly through the Watson-Crick based pairing. Elastic constants of the resulting assembly were
measured using a force calibrated dual optical trap. This study can be used to detect the existence of a target-DNA linker
with a specified nucleotide sequence, indicating its potential use in DNA biosensors.