Adding blend-shapes from Maya to Unity3d requires few steps to do in Maya (version that I’m using is 2012). There are some good videos on YouTube, where the process of bringing FBX blendshape models to Unity3D. There are few steps im Maya you need to know before starting to use the mosphed blendshapes in Unity.
First of all, blendshapes are morphed characters that are made in 3D modeling software (usally Blender or Maya). The result is a collection of different expressions i.e. separate models that blend between these models. The blending operations has to be done in Maya or Blender beforehand the models can used in Unity3d.
Bringing the models to Maya:
1. Use the windows file browser to drag and drop .obj files to Maya.
2. Click on Maya’s Pers/Outliner icon on the left side to see the models in a window.
3. From a model, select a mesh from different models that can be morphed.
4. Click on Create Deformers -> Blendshapes
5. Pers/Outliner -> select the mesh that was blended -> File -> Export Selected
6. Make sure the setting (figure) are selected. -> Import FBX
7. Drag and Drop the FBX file to Unity3D
Figure: The correct FBX export settings.