We also found that the wetting behavior and hence the contact mechanics of EGaIn are highly dependent on the ambient environment (e.g., air vs. liquid environment), which are reflected in the AFM force spectroscopy measurements. In air, an EGaIn droplet makes a contact angle of about 150 • on SAM surface (C4, C6, C8, C10), and there is significant droplet adhesion and hysteresis between the approach and retract force curves.