The FS1023 comprise a MEMS flow sensor mounted on a circuit board with an amplification circuit and a flow housing. The FS1023 is capable of measuring liquid mediums. The sensor utilizes thermopile sensing, which provides an excellent signal-to-noise ratio and is ideal for applications requiring low power. It is highly sensitive at low flow rates with a very fast response time. The set of upstream and downstream thermopiles can be used independently in a single-ended circuit or connected together in a differential configuration. Each upstream and downstream thermopiles are connected to an amplifier with a 0V to 4.5V output.