Many of the Lab’s projects are one-off solutions for a specific need. But some of our inventions are more broadly applicable. This page lists some of the most popular examples. These are now almost off-the-shelf parts. If you could use one, we can build you one quickly. We may even start offering them for sale in the future.

Phototransistor amplifier

In visual neuroscience, the exact time a stimulus is presented on a computer screen often needs to be documented along with recorded responses. Since contemporary computer hardware introduce a delay between the time the software instructs a screen refresh and the screen’s response, a common solution is to tape a photosensor to a corner of the computer screen. We have developed a sensor with readout electronics that is largely insensitive to lighting conditions and overall screen luminance. Powered from a standard 5V (USB) source, the system’s output is a TTL-compatible signal that can be captured with any DAQ system or an Arduino.

Linear LED controller

The single most-repeated request to the Neurotech Lab is for a linearly controlled high-intensity LED. These get used for microscopy, illuminating behavior rigs, even for optogenetic stimulation. We have developed a circuit that can be controlled in one of three ways:

• A manual switch turns the LED on and off while a manual knob controls intensity;
• A TTL signal (from a DAQ system or Arduino) controls on/off timing while a manual knob controls intensity;
• An analog signal from a DAQ (or Arduino) controls timing and intensity.

With a standard 5V (USB) supply, the system is perfectly suited to drive typical 3V to 3.5V LEDs. The system can readily be adapted for extra high-intensity (12V) LEDs by using a 15V or 16V power supply. Either way, the linear control ensures flicker-free operation even at frequencies invisible to the human eye.

Collimated LED light

A collimated LED light source can be inexpensively made with SMT LED and Thorlabs optomechanicals. We have PCB layouts for either OSRAM Star MCPCBs (e.g., LZ1-10B202, but many colors are available) or for various smaller LEDs. Mounted on top an SM1PL as a heatsink and placed in an SM1L15 tube with an ACL25416 as a condenser lens, these make for highly versatile light sources.

We also have a design for higher-intensity LEDs with a larger heatsink and larger collection optics.

Extracellular headstage and amplifier

Developed for use in Caltech’s undergraduate neurobiology lab course, the headstage can record extracellular signals with a noise floor as low as 1 µV. Its ability to switch between stimulation and recording in less than 1 ms, makes it possible to observe neuronal responses to electrical stimuli. A unique feature of the amplifier is a pair of lights that indicate overload condition. This makes it much easier to recognize damaged electrodes or wiring problems that are common in a classroom context.