Note: Temperature effects in the modified Howland current source for electrical bioimpedance spectroscopy

The aim of this study is to show how the modified Howland current source (MHCS) is affected by temperature changes. The source has been tested in a temperature range from 20 to 70 °C and frequency range from 100 Hz to 1 MHz. Parameters like output current, output impedance, total harmonic distortion, and oscillation have been measured. The measurements were made inside a temperature controlled environment. It was showed that the MHCS is stable at temperatures below 70 °C. Operational amplifiers with a low temperature drift and matching resistor should be carefully considered in order to prevent oscillations at high temperatures.