AutoCad is a comprehensive software that allows you to design the structures of what eventually will become your microfluidic device. This 2D drawing will be converted into a transparency mask that you will use during the soft lithography process to generate your wafer.

Working in AutoCAD can be done using command line instructions, point-and-click commands, menu selections, or a combination of all three.

Before you draw anything, make sure that the units of your document are set to microns and not inches! You will find this option in AutoCAD 201x -> Preferences -> Units and Guides.

To create objects/shapes in AutoCAD start by selecting an appropriate layer to draw it in. The pull-down layer menu is most likely found in the top right of the AutoCAD window and lists the layer name, color, if the layer is active/displayed (light bulb is on), and if the layer is locked or not (if it is locked you are not able to modify this layer). To create a new layer or modify an existing one, go to Format->Layer.

If you are designing a multilayer device, you must draw these in independent layers within the same document.

You can choose the desired shapes from the panel menu on the left of the screen, i.e. circles, lines, rectangles, polygons, etc. Click on the desired shape then click on the drawing window to initiate the shape, you can either simply terminate the shape by clicking in the drawing window or use the command line to specify quantitative details for the shape. Each particular shape will have specific parameters. For example, a rectangle will let you specify width and height, you can shift between parameters using the tab button on your keyboard.

You can also draw custom shapes using polylines, but you must ensure all shapes are closed objects.

To cancel a selection or command, click ESC on your keyboard.

Measuring Objects: To measure the length or area of a shape you simply use the ruler tool located as a point-and-click option on the top left of the window. You may also use the menu option to access this tool Tools->Inquiry->Distance or Tools->Inquiry->Area. If you want to measure length, activate this tool and click the length you want to measure in the drawing window. If you want to measure area, activate the area tool and click on the vertices of the shape you are measuring, press enter to get the final area result.

Changing Layers of Shapes: If you want to change the layer of an existing shape, simply select the shape and go to the main layer pull-down menu and click the desired layer. The shape layer will change immediately. Keep in mind that if the chosen layer is not active (light bulb is off) these shapes will not be displayed in the drawing window until you activate this layer by turning on the light bulb (clicking on the bulb).

Helpful Options: Some helpful options are located at the bottom of the drawing window including the ORTHO and OSNAP. The ORTHO option allows you to draw straight lines or move shapes in a straight line easily and snaps to the closes 90 degrees. The OSNAP option enables you to accurately select vertices on shapes and lines, making it easier to align and join objects at specific locations, etc. Once OSNAP is active and you select a shape to draw, dragging the curser across existing shapes reveals specific vertices (indicated by yellow squares) and midpoints (indicated by yellow triangles) clearly.

Xline: Construction lines are used to build reference points for your device. Use separate layers for construction lines, flow features, annotations, etc.

Mirror: Make a mirror image of an object across an arbitrary line of symmetry

Offset: Duplicates objects with a defined offset distance

Move: select the shape by clicking on it or drawing a select box around it using the left mouse button. Then right click and choose 'Move'. Click on the shape and move it to the desired location. You can also specify the number of microns you would like to move it by initiating the move in the desired direction (having the ORTHO option active at this time is recommended) and then typing the number of microns in the command line

Copy: select the shape, then click copy. Drag copy to desired location.

Rotate: the command line will ask you to specify the base point or rotation point – click on the shape to indicate this point (it is recommended to have OSNAP active at this time to quickly be able to select specific vertices). Then type the desired angle of rotation in the command line

Fillet: Pronounced “fill it,” turns a rectangular corner into a curve of defined radius. This is an important command to minimize sharp corners that can trap air in our device

Trim: Trims line or curve segments back to a preceding intersection

Extend: Opposite of trim. Extends a line until it intersects with another object

Array: Creates an array of a selected object or group of objects. Check out rectangular array vs polar array

Explode: Chops an object up into simple lines and arcs

Dimension: Allows you to measure the dimensions of an object. This tool is dynamic and will try to figure out what kind of measurement you are looking for (aligned, linear, angular, etc.)

Pedit: Use to convert objects into closed polylines. Type “pedit,” select one line segment of the object. If not a polyline it will ask to convert, enter “y” for yes, select join, highlight the object you want to close and press enter to accept. Press esc to exit the command. Now the entire object should glow when you hover over it and should say closed in the properties box under “Misc”

Hatch: This creates a hatch pattern to fill an enclosed area. Useful for checking if an object is fully closed. Disclaimer: can be a bit glitchy

Mtext: Multiline text