Method of forming a permselective layer

A method of forming a permselective layer on preselected areas of a substantially planar sensing device which comprises:

• (a) establishing at least one film comprising a silane compound mixed with a suitable solvent on a substantially planar sensing device, said compound having the formula R'.sub.n Si(OR).sub.4-n, in which n is an integer selected from the group consisting of 0, 1 and 2;
• R' is a hydrocarbon radical comprising 3-12 carbon atoms;
• and R is a hydrogen radical or a lower alkyl radical comprising 1-4 carbon atoms;
• and
• (b) heating said film to a temperature of at least about 100.degree. C. for a period of time effective to form a permselective layer having a thickness of about 1 to about 1,000 nm sufficient to provide said permselective layer with the desired semipermeable properties in which molecules having about a first preselected molecular weight or above are substantially precluded from permeating through said permselective layer, while molecules having about a second preselected molecular weight or below may effectively permeate therethrough;
• (c) establishing a photoresist layer on said permselective layer;
• (d) processing said photoresist layer using photolithographic techniques such that a proportion of the underlying permselective layer becomes exposed and subject to further processing, while those preselected areas of the device retain a protective cap of photoresist material;
• (e) removing said exposed permselective layer;
• and
• (f) removing said protective photoresist layer to leave a permselective layer over preselected areas of said device.

A method for forming a patterned semipermeable solid film onto a planar sensing device which comprises:

• (a) establishing a layer of a resist material over a planar sensing device;
• (b) subjecting the layer of step (a) to radiant energy through a photolithographic mask and developing the resultant irradiated layer such that preselected area of said device become exposed and subject to further processing;
• (c) establishing a liquid film over the patterned layer of step (b), which liquid film comprises an organosilicon compound mixed with a suitable solvent, said compound having the formula R'Si(OR).sub.3 in which R' is a hydrocarbon radical comprising 3-12 carbon atoms and R is a lower alkyl radical comprising 1-4 carbon atoms;
• (d) heating the liquid film of step (c) to a temperature of at least about 100.degree. C. for a period of time effective to form a solid film having a thickness of about 20 to about 500 .ANG. sufficient to provide said solid film with the desired semipermeable properties in which molecules having molecular weights above a given threshold can be effectively excluded from entering and diffusing through said solid film, while allowing the free passage and diffusion of lower molecular weight electroactive species;
• and
• (e) exposing the solid film of step (d) to a solvent capable of dislodging the underlying layer of resist material and allowing said solid film to separate from said device, leaving a patterned semipermeable solid film over the preselected areas of said device.

A method of forming a patterned semipermeable solid film onto a planar sensing device which comprises:

• (a) establishing a liquid film over a planar sensing device, which liquid film comprises an organosilicon compound mixed with a suitable solvent, said compound having the formula R'Si(OR).sub.3 in which R' is a hydrocarbon radical comprising 3-12 carbon atoms and R is a lower alkyl radical comprising 1-4 carbon atoms;
• (b) heating the liquid film of step (a) to a temperature of at least about 100.degree. C. for a period of time effective to form a solid film having a thickness of about 20 to about 500 .ANG. sufficient to provide said solid form with the desired semipermeable properties in which molecules having molecular weights above a given threshold can be effectively excluded from entering and diffusing through said solid film, while allowing the free passage and diffusion of lower molecular weight electroactive species;
• (c) establishing a layer of a resist material over the solid film of step (b);
• (d) subjecting the layer of step (c) to radiant energy through a photolithographic mask and developing the resultant irradiated layer such that a substantial proportion of the underlying solid film becomes exposed and subject to further processing, while those preselected areas of the device retain a protective cap of resist material;
• (e) subjecting the exposed solid film of step (d) to an etchant for a length of time sufficient to remove substantially all of said exposed solid film;
• and semipermeable solid film over the preselected areas of said device.