Ground and river water quality monitoring using a smartphone-based pH sensor

Abstract

We report here the working of a compact and handheld smartphone-based pH sensor for monitoring of ground and river water quality. Using simple laboratory optical components and the camera of the smartphone, we develop a compact spectrophotometer which is operational in the wavelength range of 400-700 nm and having spectral resolution of 0.305 nm/pixel for our equipment. The sensor measures variations in optical absorption band of pH sensitive dye sample in different pH solutions. The transmission image spectra through a transmission grating gets captured by the smartphone, and subsequently converted into intensity vs. wavelengths. Using the designed sensor, we measure water quality of ground water and river water from different locations in Assam and the results are found to be reliable when compared with the standard spectrophotometer tool. The overall cost involved for development of the sensor is relatively low. We envision that the designed sensing technique could emerge as an inexpensive, compact and portable pH sensor that would be useful for in-field applications.

A sensor-centric survey on the development of smartphone measurement and sensing systems

“…UVB measurement with smartphone camera was also used evaluate the atmospheric total ozone column [65]. UV radiation measurements using the smartphone camera were also reported by Wilkes [69]. The working principle of the instrument is shown in Fig.…”

“…The pixel-to-wavelength calibration can be achieved by testing the system with laser sources of known wavelength. The system, featuring a spectral resolution of 0.305 nm/pixel, has been tested to measure pH for river quality water assessment [69] and to measure the concentration of BSA protein and trypsin enzyme [70]. [81], Poladia et al [82] and Kumar et al [83].…”

Design of a 3D printed smartphone microscopic system with enhanced imaging ability for biomedical applications

“…These facets have limited the accessibility of the tool in resource‐limited regions (Breslauer et al ., ; Zhu et al ., ). Several research groups around the globe have recently been involved towards the development of a new platform using smartphone which can be reliably used for sensing of different physical and chemical parameters (Gallegos et al ., ; Lopez‐Ruiz et al ., ; Dutta et al ., ; Dutta et al ., ; Hossain et al ., ; Hussain et al ., ; Dutta et al ., ; Hussain et al ., ,b; Mutlu et al ., ; Chen et al ., ; Natesan et al ., ) and imaging of various biological samples (Vashist et al ., ; Knowlton et al ., ; Contreras‐Naranjo et al ., ; Scherr et al ., ; Yoon et al ., ; Sun & Hu, ; Jawale et al ., ; Purwar et al ., ). Currently, there are approximately 8.1 billion mobile phone subscribers around the world, and ∼40% of the phone subscribers use smartphones.…”

Protein, enzyme and carbohydrate quantification using smartphone through colorimetric digitization technique

“…The colorimetric response of noble metal nanoparticles has been recorded using smartphone's camera and correlated with mercury concentration , codeine sulphate and vitamin D quantification . We have demonstrated the possible use of smartphones for measuring absorption band of different colored dyes , LSPR sensing and monitoring ground and river water pH level . In some of the reported works , custom designed apps have been used for colorimetric sensing without the aid of any integrated hardware attachments.…”