Mass-based Techniques
An example of mass-based techniques is electromagnetic piezoelectric
acoustic sensors, or EMPAS that has been touted as being able to measure
multiple types of pathogens, not exclusively endotoxins, as well as
being able to detect endotoxins in real time within human blood plasma
108. Another mass-based method is magnetoelasticity
that function by placing sensors directly on to dry testing surfaces,
such as medical equipment or food. The sensor filaments, whose
oscillation frequencies are monitored, fluctuate within a magnetic
field. These sensors are coated in phages designed to bind with the
target pathogen, like ENPs 109. Then under an applied
magnetic field, the sensors will oscillate differently than before the
test, due to the increase in mass from the newly-bound endotoxin. The
change in mass is measured similar to EMPAS testing. This method has a
reported detection limit of 0.0105 EU/mL, or close to 0.001 ng/ml, and a
detection time of nearly 5 minutes.