| Popis: |
The integration of chemical sensors and biosensors with wireless communication technologies has many potential applications in areas such as healthcare, environmental monitoring, process monitoring, food quality monitoring and security. The main advantages of wireless sensors, which arise from the elimination of extensive wiring, are unobtrusiveness, lower installation costs and higher nodal densities. In this work, a low-cost, low-power photometer with the ability of wireless data transmission and data logging has been developed. It consists of an absorptiometric cell connected to a credit card- sized radio-frequency tag which has been developed specifically for use as a wireless chemical and biological sensor, and which is compatible with the International Standards Organisation ISO15693 radio-frequency identification (RFID) protocol. The absorptiometric cell itself is composed of low- cost optoelectronic components (light emitting diodes and photodiode) and contains a thin film sensing element. A colour change in the sensing film is detected by illuminating the film with light of a certain wavelength (emitted by a light emitting diode) and measuring the transmitted intensity with a photodiode. The functionality of the photometer was tested with potassium ion- sensing bulk optode membranes based on ionophore- chromoionophore chemistry as a model system. The plasticized PVC membranes incorporate valinomycin as ionophore, lipophilised Nile Blue as chromoionophore and a lipophilic salt. The response of the photometer to different concentrations of KCl was investigated. With a wide variety of potential analytes and the ability to modify the specific chemistry and optical measurement strategy, numerous applications for this type of sensor can be envisaged – from water or blood analysis and monitoring different chemical and biochemical processes to implantable sensors in the future. |
