To make it easier for other researchers to develop their own components that can interface with the MEC system, we are maintaining an open standard for MEC interfaces. The latest version of the standard is always available on this website.
MEC blocks are designed in 0.3 inch increments (a block’s nominal size in each dimension can be 0.3 inches, 0.6 inches, 0.9 inches, and so on). Each dimension of a MEC is actually designed to be 0.005 inches smaller than a 0.3-inch multiple to allow space for two MECs to be connected side-by-side (for example, the 0.3 inch thick mechanical baseboard MEC is actually 0.295 inches thick). Surfaces of MECs contain rectilinear arrays of holes spaced on 0.3 inch increments. The diameter of each hole changes along the depth of the hole: the topmost (and bottommost) 0.0865 inches of the hole has a diameter of 0.125 inches, and the middle of the hole has a diameter of 0.092 inches. The larger 0.125-inch diameter portion of the hole is designed to receive a 0.125 inch diameter and 0.175 inch long pin. Using these pins, two MECs can be connected together using a simple and reversible friction-fit assembly. Alternately, a standard 2-56 screw can fit through the 0.092-inch-diameter portion of a hole and self-thread into a 0.076-inch-diameter hole on a MEC part. This provides a mechanically stronger alternative to the pins for connecting two MECs together.
The holes on 0.3-inch-spaced increments can be sized to accommodate flexible tubing (e.g., Tygon brand) with 3/32 inch outer diameter and a 1/32 inch inner diameter. A short length of tubing inserted into a hole can then serve as a fluidic socket. A 20-gauge rigid tube (e.g., stainless steel) can then be inserted into the tubing-based fluidic socket. This creates a simple and reversible friction-fit fluidic connection between two MECs. Alternately, two MECs whose faces do not touch (and therefore cannot be easily connected by the rigid tube) may be connected using a length of flexible tubing. In this case, a 20-gauge rigid tube is permanently inserted into each MEC (extending at least 0.29 inches out of the MEC surface), and flexible tubing is slipped onto these tubes to form a reversible fluidic connection between the two MECs. For applications that must withstand higher fluid pressures, a retaining ring (0.125 inches outer diameter, 0.086 inches inner diameter, and 0.175 inches long) can be slipped on the outside of the flexible tubing at each MEC to serve as a compression fitting.
The 0.3-inch-spaced holes described above can also accommodate metal pins, conductive rubber pins, metal springs, or metal screws to provide electrical connectivity between MECs.
Optical elements like light emitting diodes, phototransistors, and fiber optics can be designed into the 0.3-inch-spaced holes and used to provide optical interfaces between MECs.