So and MIT research scientist Jeon Woong Kang designed and tested several types of optical sensors that could be placed at the tip of an epidural needle and determined that the best is one that relies on Raman spectroscopy.This technique, which uses light to measure energy shifts in molecular vibrations, offers detailed information about the chemical composition of tissueIn this case, the researchers measured the concentrations of albumin, actin, collagen, triolein, and phosphatidylcholine to accurately identify different tissue layers.