Troubleshooting common issues

Common issues encountered, their possible causes and solutions are reported in this page. If this troubleshooting chapter did not solve or list the issue, please contact the support at [email protected] for assistance.

The software reports an error at start-up

Errors at start-up may happen because of communication issues between a component of the system and the computer:

A component of the system is not powered on.
A cable is not plugged correctly.
The controllers did not have the time to boot completely. Please wait 30s when they turn a controller on before starting the software.
The USB connections did not have the time to set up or close correctly. Please always wait 30 s before the software is opened or closed.

If the issue persists after a software restart, the whole system can be rebooted:

Shut down the computer, power off the controllers and lens drivers.
Wait 1 min.
Power on controllers and drivers, reboot the computer.
Wait for an additional 30 s before starting the software.

Axis disabled or dragging error

To avoid damage, axes are disengaged when too much force or friction is measured during their movement. Common sources of axis disengagement are:

Touching an axis or exchanging a plate of the printing chamber disengaged it.
Something is in the way of the XY sled or the Z stage and induced friction during the movement to the target position.
The plate or printing chamber was not placed correctly. All plates should rest on their four edges/foot and should not be wobbling.
Plate definitions are incorrect: plate types and defined heights must be correctly set in the Exchange Plate workflow for the plates used.
Axes may lack lubricant. The Rail Lubrication should have been conducted less than 1 month ago and the last cleaning and oiling maintenance less than 6 month ago.
The software reported a Resources are busy error: another action is pending. Wait for the previous action to complete and try again or restart the software.

To re-initialize a disabled axis, restart the software.

Probe is not gripped correctly

The gripping step is crucial and most problems derive from a badly gripped tip. Hints that the gripping procedure was not conducted properly are:

The cantilever appeared poorly centered before gripping.
The Z-axis disengaged during gripping.
The air tightness failed. Leak values (after an initial spike) usually observed are <0.007 Pa at 20 mbar applied, and <0.100 Pa at 500 mbar applied.
The cantilever is not centered after gripping. If the probe was gripped correctly on a calibrated system, it should not be further than ~150 µm away from the center.
Gripping from specific ports of the probe holder plate worked better than others.

Most of those issues can happen because of:

The probe is not correctly placed in the probe holder plate. It should rest properly on the plate and should not wobble.
The probe holder plate is not placed correctly on the sled.
The Z-axis was not correctly calibrated. The head must be removed to place a reliable consumable by hand. The calibration steps Calibrate XY (Head) and Calibrate Z (Height) must be performed again.
O-ring and screw are dirty or damaged: the screw maintenance should be conducted and the damaged parts should be changed if needed.
The pressure tubing is leaking. The luer lock can be bent or damaged easily if manipulated incorrectly during maintenance operations.
In rare cases, the consumable might be defective. Please report it via e-mail.

Probe is not dropped correctly

Applying high pressure during the dropping procedure can help. Otherwise, the probe must be manually removed and the head cleaned if needed. Possible reasons for a probe not dropping are:

The probe was dropped in an already used slot.
The system was not properly calibrated.
The O-ring and screw are dirty.
The probe dried out after a long period of time and stuck to the screw.

Poor laser signal

Probable reasons for a poor laser signal after maximization are:

The laser was not aligned properly. The optimum place is about the 2/3rd of the cantilever. Scattering may deform the apparent laser spot in an asymmetric manner. Alignment should be conducted with the probe’s reflective layer in focus.
An air bubble formed after the probe was dipped into liquid. The bubble can be removed by dipping the consumable into a 50% ethanol-50% water solution, then in pure water. This can be repeated until the bubble disappears.
Air might be trapped in the channel below the chip. If the ethanol-water solution is not effective, the probe must be dropped and 15-30 µl of liquid has to be pipetted into the outer channel to remove all possible air. Please make sure a droplet always stays around the tip and pick the probe quickly as the cantilever must not dry out.
The laser window, the prism or the reflective coating of the cantilever are dirty. Unmount the head and check for prism stains, bubbles or dirt on the laser path. Clean the prism if needed.
Dirt or particles are floating in the liquid. Any particle moving in the laser path decreases the signal quality. The liquid must be changed.

Applying pressure doesn’t result in the expected flow or print

Tips usually take up to 1 min at 500 mbar to fill. Probable reasons of a larger delay are:

The consumable leaked from the inside. The probe should be dropped to check for any sign of ink outside the reservoir.
A smaller aperture and/or more viscous inks are used. Higher pressures are needed to properly fill the probe in those conditions.
The probe leaked from the outside. The Fill Probe workflow can be used to observe abnormal flows close to the cantilever.
The flow is highly directional. The nanopipette is probably broken or partially clogged and may result in anisotropic printing performances. Replace the tip if it became unsuitable for printing.
The flow is much lower that expected, the probe is probably clogged. Dipping in a relevant etchant solution for few minutes can clean the aperture from deposited material. The tip must then be cleaned from the etchant in water before printing again or changed if the performances were not improved by the etching step.
The flow is much larger than expected. Part of the cantilever probably broke, increasing the aperture opening and therefore, the flow. The pressure applied must be adapted to compensate for the larger flow or the probe changed.
The probe or the inside of the hollow cantilever dried out. This cannot be fixed and the tip must be changed.
The probe reservoir is empty. An empty reservoir could mean the probe leaked if it was not used intensively. Re-filling might not work if air becomes trapped in the microchannel.
The tip clogged while dispensing a particle suspension. Only particles small enough compared to the aperture can be dispensed.

Solution must always be filtered before use (max. 0.2 µm pore filters for 300+ nm apertures). If the tightness test is passed and the leak value at 500 mbar is small enough (<0.1 mPa), higher pressures can be tested to fill the probe. Please report leaking probes and probes that did not filled after 1 min at 1 bar via e-mail.

The printing chamber doesn’t behave as expected

If difficulties appear during printing despite the preparation workflows having been successfully performed, the printing chamber might not work properly. The potential or current may be off in a given, known, setup. 0.1 to 1mA background currents are standards for the printing chamber v3 in the Cu-SOP conditions, at -0.5V versus the AgCl reference electrode. The potential should reach the target value entered while the current slowly reaches an equilibrium value. If the potential, current or noise level are unusual or unstable, the proper assembly of the chamber might be the cause:

There are poor electrical contacts. Resistances should be ~1 ohm. Values can be checked using an ohmmeter between each electrode (WE/RE/CE) and their connector wire.
Electrodes or wires are shorted together or damaged.
The WE/sample contact is unstable or oxidized. Change the sample if needed.
Liquids were spilled or wet the outside of the chamber, especially at contacts. Micro-batteries could form and damage the chamber by dissolving contacts. Please wash and dry immediately.
An overaged or contaminated solution might not work as expected and must be regularly changed.

Disassembling, cleaning and drying the cell can be enough to solve a defective contact.

How to reboot the CERES controller

If the CERES controller returns an error and restarting CAPA doesn’t help, you might need to reboot the bot. Execute the following steps to do this:

Turn the controller off
Unplug USB otherwise the controller can still draw power via USB
Plug USB back in
Turn the controller on
Wait 1 minute
Start CAPA

How to send log files

If you encounter an error or unexpected behavior in the CAPA Operator Software, you can send us an e-mail with the log files attached. There are two types of log files which are of interest for us.

CAPA log file

Open the CAPA software
Press F12 to open the directory containing the log files
Locate the file log.txt and use it as an e-mail attachment

Event Viewer

Open the start menu, type eventvwr.msc and press Enter
Choose Windows Logs -> Application
Apply a filter to only show events from the .NET Runtime
Export the events to a file and use it as an e-mail attachment