The invention introduces a bacteria monitoring device which is user friendly and easy to handle. The device is designed based on the combination and coordination of miniaturized microfluidic platform lab-on-chip with portable optical measurement system. The microfluidic is developed using low cost glass and polydimethylsiloxane or PDMS material. The PDMS-glass based microfluidic consists of one simple inlet channel and one observation channel as shown in Figure 1 and Figure 2. The inlet channel has cross-section diameter of 1000 um and channellength of 12.5 mm. The observation channel has 15 mm x 15 mm (diameter x length) dimension which cooperates the dimension of the optical sensor.