Inkjet Printed Interdigitated Biosensor for Easy and Rapid Detection of Bacteriophage Contamination: a Preliminary Study for Milk Processing Control Applications

Abstract

Bacteriophages are responsible for significant material and time losses in the dairy industry. This because these viruses infect the selected lactic starter cultures used for milk fermentation, i.e., the first stage toward cheese production. Standard detection techniques are time- and labor-consuming, causing huge costs related to production plant sanitation and product wasting. A new type of biosensor for early detection of bacteriophage contamination is highly demanded by the milk processing market, and inkjet-printed electrochemical sensors could be the answer. Inkjet printing is a well-known technology that has been revisited in recent years, using silver nanoparticle (AgNP) based inks for low-cost and easy fabrication of sensing and biosensing systems on flexible and eco-compatible substrates. In this research, we studied inkjet printing for the manufacturing of both interdigitated electrodes arrays (IDEAs), and a versatile system to monitor bacterial cultures by electrochemical impedance spectroscopy (EIS). In particular, we studied this biosensing system for the detection of bacteriophages by comparing its performance with standard microbiological methods. We performed electrical and morphological characterizations of the devices produced with a consumer-use inkjet printer with commercial AgNPs ink on flexible substrates, such as office paper, polyethylene (PET), and photo paper. We used light microscopy optical analysis, profilometry, atomic force microscopy (AFM), and scanning electron microscopy (SEM) imaging to define the objects resolution, their real dimensions, and thickness. We also investigated the devices’ conductivity and layout, by EIS measurements with a standard buffer solution, i.e., phosphate buffered saline (PBS). Finally, we tested our system by monitoring Lactococcus lactis cultures and bacteriophage infection. We compared the results to those obtained by two standard microbiological methods in terms of response time, proving that our technique requires less than half the time of other methods and no specialized personnel.

Electrochemical impedimetric biosensors for food safety

“…The EIB is a versatile platform that can be modified to measure different food hazards through replacement of biological recognition elements. EIBs can be manufactured using consumer-grade inkjet printers (Rosati et al, 2019a , b ). The EIB for a bacteriophage produced using an inkjet printer showed better sensitivity than a traditional method for bacteriophage detection (Rosati et al, 2019a ).…”

“…EIBs can be manufactured using consumer-grade inkjet printers (Rosati et al, 2019a , b ). The EIB for a bacteriophage produced using an inkjet printer showed better sensitivity than a traditional method for bacteriophage detection (Rosati et al, 2019a ). EIBs appear to be a sensitive and cost-effective means of food hazard detection suitable for mass production.…”

“…In combination with the Internet of Things (IoT), EIBs may evolve into real-time food safety monitoring systems (Durresi, 2016). Currently, the integration of EIBs into smart devices for food hazard detection has been intensively investigated (Huang et al, 2018;Rosati et al, 2019a). However, further research is required for incorporation of EIBs into the food supply chain.…”

Interdigitated and Wave-Shaped Electrode-Based Capacitance Sensor for Monitoring Antibiotic Effects

“…We evaluated the efficacy of the fabricated IWE for the real-time impedance monitoring of the bacteria by measuring the impedance spectra using different concentrations of NaCl as electrolyte in a frequency range from 10 Hz to 1 kHz, as shown in Figure 2 . The electrical impedance characteristic of the electrode was governed by a sinusoidal signal with a frequency lower than 100 kHz applied to the electrodes; the bulk capacitance could be neglected, and the equivalent circuit can be simply designed using only an electrical conductivity of the bulk medium (R s ) and the double-layer capacitance (CPE) in series [ 33 , 34 ].…”

Thin Film-Based Sensors

“…In the article by Rosati el al. [6], a thin film produced by a consumer-use inkjet printer with commercial AgNP ink on flexible supports, such as office paper, polyethylene (PET), and photo paper, were used to monitor Lactococcus lactis cultures and bacteriophage infection via impedance spectroscopy. This method was shown to provide a response time less than half the time of standard microbiological methods, and it did not require specialized personnel to operate.…”