**Part 2**

**Chemical Sensor with Nanostructure** 

150 Advances in Chemical Sensors

Wu, W.; Wu, W.; Ji, S.; Guo, H. & Zhao, J. (2011). Accessing the long-lived emissive 3IL

Xiao, D.; Martini, L. A.; Snoeberger III, R. C.; Crabtree, R. H. & Batista, V. S. (2011). Inverse

Xiong, M.; Xi, H.; Fu, Y. & Sun, X. (2010). Synthesis and properties of novel coumarin-based

Yan, M.; Li, T. & Yang, Z. (2011). A novel coumarin Schiff-base as a Zn(II) ion fluorescent

Yao, J.; Dou, W.; Qin, W. & Liu, W. (2009). A new coumarin-based chemosensor for Fe3+ in

Yi, L.; Li, H.; Sun, L.; Liu, L.; Zhang, C. & Xi, Z. (2009). A highly sensitive fluorescence probe

Yuan, L.; Lin, W. & Song, J. (2010). Ratiometric fluorescent detection of intracellular

Yuan, L.; Lin, W. & Yang, Y. (2011). A ratiometric fluorescent probe for specific detection of

Zhang, H. & Rudkevich, D. M. (2007). A FRET approach to phosgene detection. *Chem.* 

Zhao, X.; Zhang, Y.; He, G. & Zhou, P. (2010). Highly sensitive fluorescent coumarin-based

Zhou, Y.; Liu, K.; Li, J.-Y.; Fang, Y.; Zhao, T.-C. & Yao, C. (2011). Visualization of nitroxyl in

Zhuang, X.; Liu, W.; Wu, J.; Zhang, H. & Wang, P. (2011). A novel fluoride ion colorimetric

Zuo, Q.-P.; Li, B.; Pei, Q.; Li, Z. & Liu, S.-K. (2010). A highly selective fluorescent probe for

vol.48, No.22, (May 2009), pp. 4034-4037, ISSN 1433-7851

vol.46, No.42, (November 2010), pp. 7930-7932, ISSN 1359-7345

*Commun.*, No.12, (March 2007), pp. 1238-1239, ISSN 1359-7345

vol.20, No.6, (November 2010), pp. 1307-1313, ISSN 1053-0509

*Chem. Soc.*, vol.133, No.23, (June 2011), pp. 9014-9022, ISSN 0002-7863 Xie, Y.; Dix, A. V. & Tor, Y. (2009). FRET enabled real time detection of RNA-small molecule

(June 2011), pp. 5953-5963, ISSN 1477-9226

2010), pp. 908-911, ISSN 0253-2786

2010), pp. 433-438, ISSN 1000-7032

2011), pp. 1352-1355, ISSN 1386-1425

(March 2011), pp. 1290-1293, ISSN 1523-7060

0002-7863

7003

7003

1359-7345

triplet excited states of coumarin fluorophores by direct cyclometallation and its application for oxygen sensing and upconversion. *Dalton Trans.*, vol.40, No.22,

design and synthesis of acac-coumarin anchors for robust TiO2 sensitization. *J. Am.* 

binding. *J. Am. Chem. Soc.*, vol.131, No.48, (December 2009), pp. 17605-17614, ISSN

fluorescent probes for identifying melamine. *Chin. J. Org. Chem.*, vol.30, No.6, (June

sensor. *Inorg. Chem. Commun.*, vol.14, No.3, (March 2011), pp. 463-465, ISSN 1387-

water. *Inorg. Chem. Commun.*, vol.12, No.2, (February 2009), pp. 116-118, ISSN 1387-

for fast thiol-quantification assay of glutathione reductase. *Angew. Chem. Int. Ed.*,

hydroxyl radicals based on a hybrid coumarin-cyanine platform. *Chem. Commun.*,

cysteine over homocysteine and glutathione based on the drastic distinction in the kinetic profiles. *Chem. Commun.*, vol.47, No.22, (June 2011), pp. 6275-6277, ISSN

probes for selective detection of copper ion. *Chin. J. Lumin.*, vol.31, No.3, (June

living cells by a chelated copper(II) coumarin complex. *Org. Lett.*, vol.13, No.6,

chemosensor based on coumarin. *Spectrochim. Acta A*, vol.79, No.5, (September

detection of biological samples thiol and its application in living cells. *J. Fluoresc.*,

**7** 

*2Escuela de Física and* 

*1United States 2Costa Rica* 

*Universidad de Costa Rica, San Jose,* 

**Surface-Functionalized Porous Silicon Wafers:** 

Porous silicon (PS) can be defined as a semiconductor material resulting from the electrochemical attack of a strong acid (usually hydrofluoric acid, HF), to form a network of pores with typical diameters ranging from a few micrometers to nanometers. Sometimes this material is referred to be a *quantum sponge.* The high surface-to-volume ratio (typically in the order of 500 m2/cm3), and their inherent electronic and transport characteristics make

Although the attention focus driven by PS started in 1990, some previous works have to be mentioned here. Early works on electrochemical treatment of silicon surfaces dealt with problems of anodic oxidation, electropolishing and chemical etching as early as 1937 (Güntherschulze & Betz, 1937). A more detailed study was performed twenty years later (Schmidt & Michel, 1957). The first mention of PS material (without being named in that way) was reported in 1956, when A. Uhlir Jr. found unusual deposits on anodized silicon samples (Uhlir, 1956). He supposed that those deposits corresponded to oxide forms of silicon. Shortly after this, Turner reported a more detailed study of anodically formed films on silicon (Turner, 1958). Years later, in 1971, Watanabe and Sakai reported for the first time that the electrochemically formed films on silicon surfaces corresponded to a porous nature (Watanabe & Sakai, 1971). Theunissen modelled the "formation of etch channels which propagate in crystal-oriented directions in the monocrystal" of n-type silicon the following year (Theunissen, 1972). Subsequently, interest on porous silicon began to grow slowly, and

this material suitable for development of photonic and sensing devices.

important articles dealing with different aspects of the material were published.

One of the key points for which PS attracted much attention in the decade of 1990 is the capability of the material to show photoluminescence (PL). In 1984, PL was observed at a temperature of 4.2K (Pickering et al, 1984). In this work, the PL was attributed to amorphous phases present in the porous media, but no further studies could explain all features of the process. It was until 1990, when Canham´s paper explained PL in terms of *quantum confinement* effect (Canham, 1990). This study triggered a vigorous research in the scientific

**1. Introduction** 

community, as illustrated in Fig. 1.

*1Department of Chemistry, Central Michigan University, Mount Pleasant, MI,* 

*Centro de Investigación en Ciencia e Ingeniería de Materiales (CICIMA),* 

**Synthesis and Applications** 

Fahlman Bradley D.1 and Arturo Ramírez-Porras2
