In a rehearsal for the world race, we organized a mini-race in our lab. Neutrophils from healthy donors competed for the titles of the fastest and the smartest. The race finished after six hours of intense competition. The end of the race was, literally, a photo-finish.
Our microfluidic racing chip is composed of five different channels with three more increasingly difficult challenges as neutrophils make there way up the maze. The 2D, angle/direction, gradient, and hydraulics channels test the neutrophils accuracy, while the velocity channel tests the neutrophil’s speed. The 2D channel measures the neutrophils meandering index, or how much they deviate from the direct path. The angle/direction channel measures a neutrophils ability to choose the most direct path. The gradient channel measures the neutrophils ability to choose the highest gradient of chemoattractant. The hydraulics channel looks at a neutrophils ability to sense a lower resistance, shown as the many straight channels. A maximum of 6 points can be awarded for each of the five channels. When calculating the accuracy score, penalties are given to those neutrophils that make the incorrect decision. The percentage of the incorrect decisions is deducted from the percentage of correct decisions. This fraction is then multiplied by the difficulty of the challenge ranging from 1 to 3.