SealBot
Note the larger traces required for high current handling of the heating element (nichrome wire)
Project Overview
A product that provides an air & water-tight seal to preserve any food or drink throughout the day, microwave safe, and is reusable? A group at Harvard Business School contacted me to fully develop such a product, both hardware and software. The primary condition was it had to be done in three months. Two months and twenty-nine days later I finished the working prototype, used to pitch their business to investors in Harvard and Boston.
My Role:
Everything
Mechanical design and assembly, electrical design and layout, software development and implementation. Full product development:
Electronics
I stepped down voltage from the wall to about 2v AC for the nichrome wire and 5v DC for the microcontroller, indicator LED and associated circuitry. AC and DC circuitry are clearly separated on the PCB itself for safety. I added a fuse at the very beginning of the AC input for further saftey, which came in handy several times during debugging and testing!
Software
Microcontroller is an ATtiny, programmed using an AVR cable. I used raw C++ compiled into assembly, hex, and binary files. The program does not allow the heating element to heat up without a lock activated, indicating the cover is down and the consumer can never be burned as the wire cools down so fast. Flashes an LED depending on state of product; On, Ready to Heat, Heating, and Done Heating
Mechanical
Consumer friendly, sleek design for quick placement of cups and perfect alignment every time. Designed, modeled, and built in the three month timeframe. The lid is 3D printed, with the base and electronics housing made of wood. Hinge mechanism is achieved via a dowel.
Requirements
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Safe for consumer use
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Create seal between a cup and a lid
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Easy to use, take no longer than 3 seconds
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Microwave safe
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Finish in 3 months to show investors
Highlights
The prototype did not include the heating element being attached to the lid (see video) due to the 3D printed material properties.
The heating element is nichrome wire, chosen for its ability to get extremely hot and cooling down in a fraction of a second. This achieved both the safetycomponent, as a lock and cover must be engaged to heat up the wire, and the time as it takes ~2 seconds to seal the plastic together.