MIT Media Lab researchers have developed a new process to mass manufacture self-actuating/self-sensing robots using a lamination technique where air pockets or shape memory alloy (SMA) are integrated into polyamide-based flexible circuits to produce bending actuators. Typically, flexible robots are created using manufacturing processes that have a steep learning curve to master and require the integration of mechanical parts, electronics, and sensors to function.
One of the drawbacks to producing flexible robots is that it’s a time-consuming process, which limits their mass production, making them difficult to build at scale. The researcher’s new manufacturing technique overcomes that issue while retaining standard pick-and-place surface-mount assembly and reflow processes. The secret lies in using flexible circuits, which are typically made out of polyimide polymer and laminated with copper. The researcher’s process allows them to embed air pockets inside those circuits, giving them pneumatic or SMA actuation.
The process is pretty simple and starts by cutting out the actuator design using wax paper, which is then placed on top of a flexible circuit with a vinyl coverlay sandwiching the actuators in between. The robot is then heated using an iron for temporary attachment before being slow-roasted in an oven. Since the wax paper doesn’t adhere to the coverlay material, it creates a void when air is introduced, acting as an actuator. After heating the robot, the electronic components are then assembled using a standard pick-and-place machine, and the robot is then ready for programming.
The researchers found that their starfish-like robot has an actuation peak force of 2.24N at 41.6kPa and had a maximum bend angle of 74-degrees, which was measured using a digital force gauge. It seems funny that the key to mass producing these flexible robots with self-actuators was a modification of the lamination process of the coverlay, although breakthroughs do happen without overly-complex adjustments. Those interested in a complete overview of MIT’s new manufacturing technique can read their technical paper here.