Here, we discuss an interesting concept that brings an added flexibility in chemo/bio sensing. We
present system that can be switched photonically between two states, only one of which exhibits ion-binding
behaviour. The system is based on molecular photoswitch spiropyran, which is probably the
most studied compound exhibiting above characteristics. Upon irradiation with UV light the passive
spiropyran (SP) molecule undergoes a heterocyclic ring cleavage that results with the formation of the
merocyanine (MC) which is zwitterionic form capable of ion binding. In contrast to the uncharged and
colourless spiropyran form, the merocyanine form is highly charged and can be utilized as ligand for
other charged species. Moreover, it is strongly coloured, and the colour tells us which form is present.
In addition it provides interesting information about the immediate environment of the merocyanine
binding site (e.g. polarity, presence of certain ions etc.). In this work, we present a SP-based system in
which SP is immobilized and protected within a polymeric matrix. Such system may be used for
detection of metal ions in highly polar solvents, e.g. water. The response characteristics and kinetics of
MC-Cr3+ complex formation and SP-MC switching within the polymer matrix have been determined.
Simple light emitting diodes (LEDs) have been employed for photoswitching and colorimetric
measurement of SP-MC switching and MC-Cr3+ complex formation as light sources and detectors.
The integration of chemo/bio sensors in large wireless sensing networks (WSN) is currently limited,
largely due to the issues related with power consumption and data handling. Also, there are very few
low cost chemo/bio sensors that combine sensitive, low limit of detection capabilities with simple
experimental setup. However, with recent advances, ion-selective electrodes (ISEs) may become an
excellent candidate for deployment in WSNs.
In this paper, we describe a solid-contact electrode based on poly(3-octylthiophene) (POT) as an
internal contact. We report its characteristics and its application to the for measurement of Pb2+ in 16
soil samples, with a ultimate goal of producing a small, simple and sensitive sensor that can be
integrated into WSNs. The electrode had a detection in the soil digestion matrix (1×10-3 M HNO3) of
1×10-7 M (20 ppb). The electrodes results were compared with atomic absorbtion spectrometry (AAS)
as a common instrumental technique used in soil analysis. We also report on the performance of solid-contact
ISEs based on polypyrrole (PPy) and POT. A superior detection limit of POT- relative to PPy-based
ISEs was observed. Furthermore, a good correlation has been observed between POT-based ISEs
and AAS and between the two types of ISEs.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.