**Author details**

uses gold substrates instead. In summary those results clearly show that the p-Si sensor shown here has a good selectivity and sensitivity to the target compound, two very impor‐

An overview of the requirements for a good performance of a p-Si biosensor was presented and the generalities of the fabrication of different kinds of these biological sensors as well. In

Sensors allow our systems and devices to be in relation with the real events that we need to register or control. So, precision (same response to the same stimuli: repeatability) and accu‐ racy (indicating magnitude value as close as possible to the real magnitude of the stimulus to be sensed: minimum absolute error spread) are two main requirements for any sensor when the industry selects a structure type for market use. However, other properties will define the success of a new kind of sensor in the market. These are: technological compati‐ bility with the existing devices, geometric dimension requirements, low noise insertion, ease of adjustment and setup, low power consumption, performance standardization (linear if possible), low thermal or aging characteristic drifts, robustness, reliability, low obsolescence, and very wide field of applications. p-Si is a material that accomplishes all of these require‐ ments with enough margins to think that it will become increasingly popular in the short term. For instance, integrated circuits (IC) are made of crystalline Silicon, which means it is fully compatible for associating a p-Si sensor to any electronic device. The electrochemical technology used to create a p-Si layer does not collide with the IC lithography. The geomet‐ ric dimensions required to create this type of sensor are sufficiently small to be integrated in an IC. The homogeneity of the porous and its radius control (internal surface density con‐

An important factor to take into account in the implementation of a p-Si biosensor is its chemical stability after sample storage. Due to its high superficial area, p-Si based materials tends to be oxidized when are exposed to air ambient conditions. This oxidation plus the ad‐ dition of other molecules present in the air ambient could modify the biosensor reponse to an analyte after certain amount of time. Pasivation techniques and surface functionalization described before have been proved being successful to prevent or minimize these stability issues. Work has to be done in order to improve the existing methods and assure the repro‐

Porous silicon has proven to be a succesful material for biosensing applications [1, 58]. In some cases even femtomolar concentrations in biomolecules was demostrated [1]. The wide range of applications in sensing biological substances include: healt applications [7, 43, 58], virus detection [43], inmunosensors [59, 1], DNA biosensors [58,60], drug delivery [16], bio‐ security on food [61], biological warfare agents [62], implantable biosensor technology [58], among others [12, 15, 63]. Some new trends in the fabrication of p-Si biological sensor devi‐ ces are the use of nanomaterials [54]. The sensitivity and performance of biosensors are be‐

the next section we will discuss the new materials, uses and future of porous silicon.

tant characteristics that a sensor ought to have.

154 State of the Art in Biosensors - General Aspects

**4. Future of porous silicon biosensors**

trol) as well as its layer stability is improving very fast.

ducibility of p-Si biosensors reponse over a lapse time of years.

M. B. de la Mora1 , M. Ocampo2 , R. Doti2 , J. E. Lugo2\* and J. Faubert2

\*Address all correspondence to: je.lugo.arce@umontreal.ca

1 Instituto de Física. Universidad Nacional Autónoma de México. Circuito de la Investiga‐ ción Científica Ciudad Universitaria, México

2 Visual Psychophysics and Perception Laboratory, School of Optometry, University of Montreal, Canada
