Document Type



Biological and Chemical Physics | Biophysics | Biotechnology | Life Sciences | Physics

Publication Details

Analytical Chemistry, vol. 91. no. 19. This document is the Accepted Manuscript version of a Published Work that appeared in final form in Analytical Chemistry after technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/10.1021/acs.analchem.9b02628


Continuous monitoring of bacterial growth in aqueous media is a crucial process in academic research as well as in the biotechnology industry. Bacterial growth is usually monitored by measuring the optical density of bacteria in liquid media, using benchtop spectrophotometers. Due to the large form factor of the existing spectrophotometers, they cannot be used for live monitoring of the bacteria inside bacterial incubation chambers. Additionally, the use of benchtop spectrometers for continuous monitoring requires multiple samplings and is labour intensive. To overcome these challenges, we have developed an optical density measuring device (ODX) by modifying a generic fitness tracker. The resulting ODX device is an ultra-portable and low-cost device that can be used inside bacterial incubators for real-time monitoring even while shaking is in progress. We evaluated the performance of ODX with different bacterial types and growth conditions and compared it with a commercial benchtop spectrophotometer. In all cases, ODX showed comparable performance to that of the standard benchtop spectrophotometer. Finally, we demonstrate a simple and useful smartphone application whereby the user is notified when the bacterial concentration reaches the targeted value. Due to its potential for automation and mass production, we believe that the ODX has a wide range of applications in biotechnology research and industry.

2021-11-04_Cappa-art_Edikit_Chinna-et-al.pdf (1553 kB)
1. GitHub links for project files 2. Bill of materials 3. Instructions to build ODX 4. Firmware instructions for ODX a. Board manager b. Flashing a soft device c. Flashing ODX firmware d. Device setup for black magic probe 5. Tools used 6. Raw data for Figure 6