Designing an instrument for the measurement of very low electric current has a few challenges. Here, at KAFTS, we have decided to undertake the task of investigating is it possible to design a cost-sensitive, digital DC picoammeter. We have set an additional objective that the sensing resistor resistance shall be as low as possible. This goal is challenging due to thermal noise, which raises proportionally to the square root of resistance. With the higher resistor value, the useful signal to noise ratio is better for a given electric current value. Nevertheless, thanks to smaller resistance, the drop voltage is also less significant, making the device more beneficial with specific transducers. 

The result was very positive. We came out with the battery-powered, digital and low-cost device that provides an easy user interface and auto-calibration functionality.

Our device already found applications in molecular biology and spectrometry, fascinating disciplines!

We also want to thank the Physics Open Lab for the fantastic review. We are happy that our picoammeter is a part of such a great laboratory!

If you wish to buy our product, please note that it is available on eBay.

Picoammeter.jpg

Device Parameters:


Mode 1

> Resolution: 1 pA,

> Range: +- 500 nA

> Sensing Resistor: 1 MOhm

> Voltage Drop: 1uV / 1pA
Mode 2

> Resolution: 1 nA

> Range: +- 500 uA

> Sensing Resistor: 1 kOhm

> Voltage Drop: 1uV / 1nA
Mode 3

> Resolution: 0.1 uA

> Range: +- 50 mA

> Sensing Resistor: 10 Ohm

> Voltage Drop: 10uV / 1uA

Error: +- (2% + 2)
Reading frequency: 2 Hz.
Maximum reading stabilization time: 10 seconds.
Operating temperature range: 10 - 30 Degrees Centigrade.
Operating humidity range: 20% to 60%.
Dimensions: 100 mm x 100 mm x 26 mm.