Additively Manufactured Flow-Resistive Pulse Sensors

Resistive pulse sensors (RPSs) provide detailed characterization of materials from the nanoparticle up to large biological cells on a particle-to-particle basis. During the RPS experiment, particles pass through a channel or pore that conducts ions, and the change in the ionic current versus time is monitored. The change in current during each translocation, also known as a "pulse", is dependent on the ratio of the particle and channel dimensions. Here we present a facile and rapid method for producing flow-RPSs that do not require lithographic processes. The additively manufactured sensor has channel dimensions that can be easily controlled. In addition, the fabrication process allows the sensor to be quickly assembled, disassembled, cleaned, and reused. Furthermore, the RPS can be created with a direct interface for fluidic pumps or imaging window for complementary optical microscopy. We present experiments and simulations of the RPS, showing how the pulse shapes are dependent on the channel morphology and how the device can count and size particles across a range of flow rates and ionic strengths. The use of pressure-driven fluid flow through the device allowed a rapid characterization of particles down to concentrations as low as 1 × 10^-3 particles per mL, which equated to one event per second.