Prototype Like a Pro

For an electronics hobbyist, when inspiration strikes it is time to draw up a design and acquire the parts in the bill of materials. canning the products at any electronics distributor, you will find a huge selection of sensors and other components to fit most any need — but the form factors are usually a one-size-fits-all square or rectangular shape. These components need to fit the device in the mind of the hobbyist, whether that be a pair of glasses, a wristwatch, or otherwise. It is no surprise then that these device prototypes are often a mess of wires and hot glue that are several times larger than they should be.

A team at MIT’s Computer Science and Artificial Intelligence Laboratory has developed a new tool that can tame the wild prototypes of a hobbyist. MorphSensor is a 3D design tool that can be used to reform existing sensor modules to fit into a new, arbitrary form factor.

To use MorphSensor, a 3D model of the object to fit the sensor to can be either created or imported into the software. Next, the sensor module is separately added to the design space. From this point on, MorphSensor works similarly to traditional electronics CAD software, but in three dimensions. Components can be dragged from the sensors onto the object, then rotated and adjusted as desired. After placements are complete, air-wires are shown where electrical connections need to be made so that the user can route wires to complete the circuit.

Of course you will not be able to send your completed design off to your favorite green or purple PCB manufacturer — a custom fabrication process must be followed. The team used an inkjet printer with conductive silver ink (a conductive ink pen can be substituted) to lay out the main circuit traces. A set of prefabricated component footprints called BigFoots was used to solder each part to. The footprints are then attached to the circuit traces with the help of double-sided, electrically conductive tape. Another strip of double-sided tape is used to affix the sensor to the object of interest.

As a proof of concept, the MorphSensor team converted a light sensor module into a design that could fit on a pair of eyeglasses. The light sensor was placed on the front of the glasses, to accurately detect the level of light reaching the wearer’s eyes, while the microcontroller and supporting circuitry were located out of the way on the eyeglass temples.

MorphSensor represents an innovative approach for adding sensors to device prototypes. In addition to adding flexibility to designs, the method is also faster than sending the design out to a traditional PCB manufacturer, although the MorphSensor designs do not have the same level of durability.