This circuit can easily be assembled on a small piece of prototyping board. Use low-current types for the LEDs. They have a low forward voltage and are fairly bright at current levels as low as 1 mA.

My wish list for highly-integrated measurement instruments includes impedance or RLC meters. These instruments are especially interesting because they allow for so many different design alternatives ...

Researchers have co-opted glucose meters to detect infectious agents, including SARS-CoV-2, by pairing the devices with synthetic gene circuits that produce glucose in response to target analytes. The ...