Surgical end effectors are disclosed having angled tissue-contacting surfaces. In some embodiments, the mobile devices may transmit a non-immediate block acknowledgement request during the communications phase. The helical needle is advanced into the heart wall, and is used to stabilize the heart and to pass a purse string suture through the heart tissue. A compression spring is inserted on the shaft of the bolt between the adjustment means and the mainframe. Each MEMS tilt mirror in the two dimensional array can tilt about two non-colinear axes and is suspended by a plurality of suspension arms attached to a silicon on insulator substrate.