Porous silicon in drug delivery devices and materials

Mesoporous silicon microparticles for oral drug delivery: loading and release of five model drugs.

The biocompatibility of mesoporous silicates.

Mesoporous silicon in drug delivery applications.

We have reviewed the humidity sensors based on ceramic materials. We first discuss the operating principle of ceramic humidity sensors. This is followed by a section on the relationship between the conduction mechanism and microstructure characteristics of the sensing elements of ceramic humidity sensors. This part of the review is also focused on the methods for optimization of the microstructure of ceramic porous elements. The next section summarizes the information on the materials used for the ceramic humidity sensors fabrication and effect of dopants or hybrid compositions on the sensing ceramic-based materials. Then we analyze state-of-the-art techniques for producing ceramic sensors. The key research and technological challenges in the field are discussed at the end of the review. The review is based on 424 references published during from 1998–2013.

Recent trends of ceramic humidity sensors development: A review

Surface chemistry and pore size affect carrier properties of mesoporous silicon microparticles.

Thermally-carbonized porous silicon films have been prepared by exploiting the dissociation of acetylene. Thermoanalytical methods have been used to study the oxidation behavior of these films in different oxidizing ambients. The results have been compared to other stabilization methods. Due to enhanced adsorption and only slightly reduced specific surface area, the carbonization of porous silicon was found to be an attractive treatment for sensing applications. The possible post-treatments are also discussed.

Studies of Thermally‐Carbonized Porous Silicon Surfaces

The room temperature oxidation of porous silicon

Different ways to reduce hysteresis in a capacitive-type thermally carbonized porous silicon (TC-PS) humidity sensor are studied and compared. Modification of the contact angle of the dielectric surface, enlargement of the pore size of dielectric, and operating the sensor at elevated temperature proved all to be possible ways to reduce hysteresis in a TC-PS humidity sensor. By variation of the carbonization temperature, we produced TC-PS surfaces of different contact angles. Although the hydrophobic surface prevents hysteresis, it also decreases considerably the sensitivity of the sensor. Enlargement of the pore size reduces and tunes the hysteresis loop into the higher relative humidity (RH) values. Also operation of the sensor only few degrees above room temperature was found to be a workable method to prevent hysteresis. However, a constant temperature is crucial for exact humidity measurement using a TC-PS sensor

Studies on hysteresis reduction in thermally carbonized porous silicon humidity sensor

Different kind of drugs can be loaded into the porous silicon microparticles for oral dosing. In cases where the drug is in its crystalline form in the pores, the amount of the loaded drug can be determined accurately using a calorimetric method, thermoporometry. Even if the drug substance is not in crystalline form a sophisticated estimation can be given. In this work ibuprofen, antipyrine, and ranitidine have been studied. Ibuprofen and antipyrine were easily detected and quantified, but ranitidine, which does not penetrate into the PSi microparticles in its crystalline form, could only be qualitatively determined. The possibility to quantify this kind of drug substance is also discussed.

V.-P. Lehto

Papers

Surface chemistry and pore size affect carrier properties of mesoporous silicon microparticles.

Studies of Thermally‐Carbonized Porous Silicon Surfaces

The room temperature oxidation of porous silicon

Studies on hysteresis reduction in thermally carbonized porous silicon humidity sensor

Determination of drug load in porous silicon microparticles by calorimetry