Hardware Operation

Loading the Device

Loading AduroTM devices is a quick and easy procedure.  Start by carefully placing the AduroTM device on the end of the AduroTM TEM holder using tweezers.  The gold contact pads at the edge of the device should be facing the holder as shown below.  Next, raise the holder electrodes by pressing down on the plastic piece.  Then, slide the AduroTM device toward the holder into position under the holder electrodes.  Slide the device until it stops.  Finally, release the plastic piece and allow the holder electrodes to drop on to the gold contact pads on the device.  The device will be secured in the holder, and its membrane will be centered on the through-hole beneath the device.

Using the Check Connectivity Function

After loading the device, verify that contacts between the holder electrodes and the device contact pads are acceptable.  If the device is loaded improperly, or if the sample prep process has bridged the electrodes, the device will not respond correctly during heating.  Under “XXX” in the menu, select “Check connectivity”.  This will force a small current through the device and determine if the device has the correct resistance, or if there is an “open” or “short” present.  If an “open” condition is indicated, the device should be removed from the holder and the device loading process repeated as outlined above.  If the “short” condition is identified, the device should be carefully removed from the holder and inspected.  Please refer to the AduroTM system manual for more information.

Software Operation

Load the Calibration File

After the device is loaded and the “check connectivity” function is run, the device calibration file must be loaded.  Under “XXX” in the menu, choose “Load cal file” and select the appropriate device calibration file.  

Manual vs. Automatic Mode - Your Choice

The AduroTM system can apply heat using either a “manual” mode or an “automatic mode”.   
The manual mode allows users to directly enter a temperature value and remain at that temperature indefinitely while imaging, until a new temperature is desired or until the end of the experiment.  This mode is “time-independent”.
Alternatively, the automatic mode allows users to create custom, precise temperature profiles over time, with time scales down to one millisecond.  Numerous functions are available, including single pulses, repeated pulses, and fast /slow ramps, providing complete control of temperature vs. time for any experiment.

Manual Mode

The Manual Mode is chosen by selecting “ Edit -> Manual Editing Mode “ from the menu.  A dialog box will open where the temperature can be entered in °C.  After pressing the “Update” button, the temperature is applied to the sample
Immediately, upon heating, the sample will appear to shift due to localized thermal expansion of the membrane.  The sample will stabilize quickly and it’s ready to image with negligible drift.
The sample is then held at the desired temperature until another temperature value is entered, or until the experiment is concluded using the “Quit” button.  As temperature is increased or decreased, there will only be slight drift in the X- and Y- directions as the membrane stabilizes.  Z-direction changes will require focus adjustment.

Automatic Mode

The Automatic Mode is chosen by selecting “Add Function” on the main screen.  Several different functions are available. When the desired function is chosen, a dialog box will open where parameters such as the time and temperature can be entered.  A list of functions, called a “script” can be designed to execute a complex series of commands.  After a complete script is designed, pressing “Send Script” will start the test sequence at the sample.
Immediately, upon heating, the sample will appear to shift due to localized thermal expansion of the membrane.  Large, quick changes in temperature will both shift in the Z-direction and may slightly drift in X- and Y- before settling.  After a pulse or series of pulses, the sample will stabilize quickly back to its initial room temperature conditions, and it’s ready to image with negligible baseline drift.
Upon completion of the test sequence, the sequence can be rerun or edited.

Troubleshooting

Connectivity Problems – opens and shorts

The “Check Connectivity” function is designed to verify that the electrical connections to the device are valid prior to heating. An open circuit or a short circuit can cause a connectivity failure.   An open circuit is typically due to either (1) a broken membrane or (2) holder electrodes not contacting the pads on the device.   In the event of an open circuit, the holder tip should be inspected using a stereoscope.  Broken membranes are easily identified in the microscope and result from mishandling during sample prep – devices should be handled gently to avoid breaking the membrane.  The connection between holder electrodes and the contact pads should also be inspected to ensure that these features are well-aligned when the device is fully inserted.  If the electrodes and contact pads are NOT aligned well, unload and reload the device carefully, and check the connectivity again.

Appearance and Features of the Devices

A key feature of the microheating devices is the membrane region.  The thin membrane region is a square-shaped, freestanding, nanocrystalline thin film.  Current is forced through the membrane from one side of the device to the other.  An array of larger holes can be found in the center of the membrane, and imaging is performed through these holes.  Often, a layer of holey carbon with smaller holes is placed atop the membrane to support nanoparticles and other small samples over the holes in the membrane.   It may be confusing for first-time users to see the holey carbon film on membrane hole array, but it’s helpful to remember that you should image through the large holes. A good imaging strategy starts with locating the approximate center of the membrane hole array, then inspecting individual holes to identify the best sample(s) for the experiment.  

Focus Adjustment

As with all materials, the heating membrane expands as it heats.  However, since the heat is strongly localized to the membrane, the edges of the membrane and the device substrate do NOT expand.  This pins the edges of the membrane, and the expanding membrane is forced upwards.  In the microscope, this displacement may require an adjustment in focus between temperature settings.

Drift over Temperature

By confining heat to the membrane portion of device, conventional thermal drift is nearly eliminated.  Some drift will be observed as the device heats/cools quickly (for example, if a quick heat pulse is applied) and the membrane expands or contracts.  This effect often stabilizes quickly and the drift will disappear after a short time.  Minor adjustments in X-, Y- and Z- settings may be required as temperature is changed.

Tilt and Touch Alarms

The Protochips AduroTM holder provides alpha tilt (single tilt). The maximum tilt is a function of the holder design and the pole piece gap of the microscope.  Please contact Protochips to determine the approximate tilt range for your particular configuration.  If, during use, a “touch alarm” occurs, stop immediately and return the holder to a zero-tilt condition.  Exceeding maximum tilt can damage the holder and/or the microscope, and users are encouraged to exercise caution during operation.