Francisco J. del Campo

Amperometric detection of Enterobacteriaceae in river water by measuring β-galactosidase activity at interdigitated microelectrode arrays

Two simple methodologies are compared for the detection of faecal contamination in water using amperometry at gold interdigitated microelectrodes. They rely on the detection of β-galactosidase (β-gal) by redox cycling amperometry of the p-aminophenol (PAP) produced by the enzyme from the 4-aminophenyl β-d-galactopyranoside (PAPG) substrate. The use of phages as specific agents for the release of the bacteria-enclosed enzyme allowed the detection of 6×10(5) CFU mL(-1)Escherichia coli in 2 h without any pre-enrichment or preconcentration steps. Better limits of detection were achieved for the second strategy in the absence of phages. In this case, bacteria were enriched in the presence of both β-d-1-thiogalactopyranoside (IPTG) and substrate but in the absence of phages. Under such experimental conditions, 5×10(4) CFU mL(-1) E. coli could be detected after 2 h of incubation, while 7 h of incubation were enough to detect down to 10 CFU mL(-1) in river water samples. This represents a straightforward one-step method for the detection of faecal contamination that can be conducted in a single working day with minimal sample manipulation by the user.

Suspended Silicon Microphotodiodes for Electrochemical and Biological Applications

Local electric stimulation of tissues and cells has gained importance as therapeutic alternative in the treatment of many diseases. These alternatives aim to deliver a less invasively stimuli in liquid media, making imperative the development of versatile micro- and nanoscale solutions for wireless actuation. Here, a simple microfabrication process to produce suspended silicon microphotodiodes that can be activated by visible light to generate local photocurrents in their surrounding medium is presented. Electrical characterization using electrical probes confirms their diode behavior. To demonstrate their electrochemical performance, an indirect test is implemented in solution through photoelectrochemical reactions controlled by a white-LED lamp. Furthermore, their effects on biological systems are observed in vitro using mouse primary neurons in which the suspended microphotodiodes are activated periodically with white-LED lamp, bringing out observable morphological changes in neuronal processes. The results demonstrate a simplified and cost-effective wireless tool for photovoltaic current generation in liquid media at the microscale.

Introduction to Electronics. Study, Design and Validation Tests

This chapter presents in detail the design and validation of specific instrumentation electronics regarding ac and dc electrochemical applications. The development of such electronics will be defined through a design architecture that will build up for an easy and understandable way for its design and validation for different applications.

Electrochemical DC Techniques. Glucose Monitoring and Multi-parametric Detection

This chapter focuses on the conception and design of an autonomous and disposable multi-parametric analyzer for the early diagnosis of diabetes mellitus and its different associated risk factors.

Impedance Analysis AC Techniques. Cellular Quantification

This chapter describes the AC techniques for detection, quantification and monitoring of diluted cells suspensions. Electrochemical Impedance Spectroscopy (EIS) and Impedance Analysis (IA) are the techniques presented on this chapter as means to develop a compact, portable and user-friendly solution for accurate, reliable, and cost-effective cellular quantification.

Introduction to Electrochemical Point-of-Care Devices

In this chapter an introduction to the different types of Point-of-Care (POC) devices is presented. The variety of these devices is quite important in terms of device design considerations, which depends on their field of application, and budget constrains. The impact of POC in healthcare landscape is increasing. There is a special interest on portable and easy-to-use solutions. There are different settings that define the design of the device. These settings are the choice of materials, fluidics for actuation and control, sample preparation, recognition and capture, signal detection and driver amplification, etc. Our attention is focused into the particular case of Electrochemical Point-of-Care Devices. In this case the signal detection is based on an electrochemical transducer.

Project-Based Engineering Learning for BME: Electrochemical Instrumentation

Different electronics solutions are introduced in the present book from an advanced point of view. Some applications are introduced where these electronic circuits are implemented like in the case of the glucometer. This chapter aims to introduce a comprehensive approach to electronic circuits, techniques and electrochemical sensors in POC devices to a general audience of undergraduate students in biomedical engineering, in particular, and electronics engineering, scientists, and engineers, in general. In the case of undergraduated biomedical engineers, the academic program complexity asks for solutions like the presented here where the introduction to the analogue electronics and instrumentation, for a particular case like voltammetry, is developed through a Project-based learning solution. An instructor can follow the presented methodology.