Monday, February 27, 2012

How a liquid lens works (electrowetting)



A liquid lens works by changing the shape of a water drop by creating an electrostatic field that pulls on the water molecules. I show how water can be affected by a high voltage supply and an electrostatically charged comb.

The process by which the droplet changes shape is known as electrowetting.

Friday, February 17, 2012

Projector HID arc light mounted into a desk lamp



I combined the High Intensity Discharge bulb and power supply from an old LCD with a desk lamp to create a 270W spotlight. I bypassed the power supply's interlocks and shorted an optocoupler to cause the power supply to always turn the lamp on when AC power is applied. I used an inline power switch to control the device. The desk lamp's existing wiring is able to withstand the high starting voltage of the HID lamp (probably a few KV). Once the arc strikes, the voltage is much lower and the current much higher.

Sunday, January 29, 2012

Freeze-drying Jello gelatin with an improved cold trap



I built an improved cold trap from an aluminum pan and a stainless steel bowl. It held more ice than my original copper pipe cold trap, but the 100ml of water from the gelatin still managed to almost plug up the trap.

Yeast cells under the microscope



These bakers' yeast cells might be reproducing in the video. It's hard to tell if its just movement from the water under the cover slip

Creating aerogel with supercritical methanol



In previous videos, I used supercritical CO2 to dry my homemade aerogels. This time, I soaked the aerogel in methanol, then raised the temperature and pressure of the methanol itself to make it supercritical. This allows the gels to be dried without an additional solvent exchange into CO2. The downside is that it requires a chamber full of methanol at 460*F and over 1200 psi, which is a much bigger hazard than using CO2.

The aerogels dried with methanol shrank less than the ones dried with CO2, but there was still a lot of cracking, and I have yet to create a high-quality monolith.