6.810 Engineering Interactive Technologies - Fall 2018
Team 17 - Sabina Chen and Lantian Chen
Sometimes when people are running or doing hard work, the accessories they wear can get in the way, and they would take the accessories off to avoid inconvenience. What if the accessory itself can adjust its shape according to the physical state of the wearer?
People also adjust their choice of accessories according to the weather, the social occasions they are about to attend, the color themes of their clothing, etc. What if the accessory itself can make changes in response to these factors?We designed a type of flower-shaped earrings that can:
Photoresistors are integrated onto the earrings themselves to measure light intensity. To measure the heart rate, we paired our earrings with a wristband and finger strap for pulse sensor. An arduino is strapped to the back of the user’s neck, connected with both earrings by wires.
We used a pulse sensor to determine the activity level of the user, and a photoresistor to determine the lighting conditions of the user's environment. The feedback from the sensors will enable the earrings to adapt appropriately. The photoresistor is embedded directly in the earrings whereas the pulse sensor is attached via a finger strap and bracelet. When a user's pulse is at rest, the earrings will bloom; when active, the earrings will shrink. Additionally, when there is light, the earrings will bloom; when dark, the earrings will shrink. The sensors send signals to an arduino, which controls a relay that powers the actuator. All sensors and actuators are connected to a micro-controller (Arduino Uno), which is worn as a necklace at the back of the user's neck.
For the actuator we used a type of shape memory alloy, Flexinol Wire, which contracts when heat is applied. Applying ~400mA of current to the wire heats up the wire enabling it to decrease a maximum of 10% in length. Dynalloy Flexinol Wire is made of nickel-titanium, and the small diameter of these wires enable the wires to contract like muscles when electrically driven. We used a Flexinol Wire with a diameter width of 0.006". In order to give the earrings the illusion of "blooming" we sewed the flexinol wire to the individual petals in such a way so that when the wire contracts, the petals are bent forward. With four petals bending forward at once, the earring looks like a blooming flower. The petals are cut out of origami paper so that the muscle wire has enough force to move the petal. Because the arduino itself does not provide enough current to contract the memory alloy, a relay was used to wire a separate power source (ie. a 9V battery) to the actuator. A system diagram of the control flow is pictured below.
Pulse Sensor Bracelet
Photoresistor Embedded into Earrings
Flexinol Wires Contracting/Blooming
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Integrated Adaptive Earrings