AIR LAMP: Full Study

1. Electronics:

The project uses an Arduino Nano 33 IoT as the microcontroller. It controls two 4.5V DC mini air pumps, one for inflation and the other for deflation. A 6V solenoid air valve was also used to switch the airflow. They are all powered by 5V DC, which is regulated by a 7805 voltage regulator. The pumps are turned on and off through two TIP 102G transistors.

In the prototype on the right, I made one button that activates the inflation pump and one button that activates the deflation pump.
According to the design, the lamp's membrane should function as the button. That means I need some measurements for when the lamp is pressed. An air pressure sensor is ideal because it can detect the increase in pressure regardless of which part of the lamp is pressed.

Another measurement I need is to know when the lamp should stop inflating or deflating. Air pressure is already used to detect interaction, but it is also susceptible to changes in temperature and the aging of the material. In the end, a short-ranged time of flight sensor is chosen because it has a small cone area for detection, and distance is a good measurement for the size of the lamp. Both sensors are soldered onto a protoboard that was to be embedded inside the lamp.

Colde white LED lights were combined with warm off-white LED strips

2. Fabrication:

The main choice of material is Ecoflex 00-30, which is very soft, elastic, and translucent. The main challenge is to make an air-tight encapsulated chamber that allows wires and the silicone tube to pass through. The sensors also need to be embedded inside. Ecoflex 00-30 needs to be cast into a mold to cure. Therefore, the encapsulated chamber needs to be cast in two parts and then sealed together.

Some design graphs

3D printed molds for the top silicone -- modeling credited to Yihua Li

Casted silicone membrane (holes were patched using more silicone later.) The silicone tube was encapsulated by the membrane

The bottom half of the lamp is cast in two layers. The first layer is a thin flat silicone layer. On top of the thin layer, a laser-cut birchwood round disc painted in white is placed. The protoboard with all the sensors is then placed on the round disc. A second layer of silicone is then cast onto the surface, encapsulating all the components inside.

Seal the top and bottom layers together with excessive silicone – done!

3. Programming:

The logic of the lamp's program is cycling through four stages: off—inflating—staying on—deflating. Each of these stages has an expected height, as monitored by the ToFL sensor. Whenever the lamp is below the expected height, the program will activate the inflation pump. Vice versa, when the lamp is above the expected height, the deflation pump will be activated. Otherwise, the air valve will be shut to keep the air inside.

During the off and staying-on stages, the air pressure sensor will monitor the PSI of the interior. When there’s a sudden increase in the pressure, the program will move on to the next stage, either inflating or deflating by setting a different expected height of the lamp.