Detecting passage of a particle into a target location

An apparatus, comprising:

• a fluidic input configured to receive a sample;
• a die including a microfluidic chamber, wherein the microfluidic chamber includes:
• a reservoir in fluidic contact with the fluidic input;
• a microfluidic path coupling the reservoir to a foyer, wherein the foyer is configured to contain a portion of the sample;
• a first sensor disposed within the microfluidic path, wherein the first sensor is configured to detect passage of a first particle of the sample;
• a nozzle configured to eject a volume of the portion of the sample into a target location;
• and
• a second sensor configured to detect passage of the first particle of the sample past the foyer;
• and
• a circuitry configured to:
• control firing of the nozzle based on signals received from the sensors,
• enter an alternate action in response to detecting a second particle signal at the first sensor before the second sensor has detected the signal of the first particle while the first particle is still in the foyer, wherein the alternate action includes first stopping dispensing, then moving to a spittoon location and then clearing the foyer of particles before returning to an original location and resuming dispense operations to decrease a probability of dispensing multiple particles into a location when a single particle is intended;
• and
• record in a dispense map, an indication of whether the target location includes a single particle or multiple particles based on signals measured by the first sensor and the second sensor.

A non-transitory computer-readable medium storing instructions which, when executed by a processor, cause the processor to:

• detect passage of a first particle of a sample along a microfluidic path, via a first sensor disposed within the microfluidic path, wherein the microfluidic path couples a reservoir storing the sample and a foyer;
• eject a volume of the sample into a target location via a nozzle;
• detect a second particle signal at the first sensor before the second sensor has detected the signal of the first particle while the first particle is still in the foyer;
• in response to detecting the second particle signal:
• enter an alternate action to first stop dispensing, then move to a spittoon location, then clear the foyer of particles, then return to an original location, and resume dispense operations to decrease a probability of dispensing multiple particles into a location when a single particle is intended;
• stop firing the nozzle responsive to detecting passage of the first particle via a second sensor disposed between the first sensor and the nozzle;
• and
• record in a dispense map, an indication of whether the target location includes a single particle or multiple particles based on signals measured by the first sensor and the second sensor.