# US 2014/0151538 A1 · Fouling layer detection on an environmental sensor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0151538 A1 - Document ID: US20140151538A1 - Status: Published application - Kind: A1 - Application number: 14/064,607 - Filed: 2013-10-28 - Published: 2014-06-05 - Earliest claimed: 2012-11-30 - Assignees: NXP B.V. - Applicants: NXP B.V. - Inventors: Aly Aamer Syed; Manvi Agarwal - Web page: https://patentgrep.com/patent/US20140151538A1 ## CPC - G01N 21/17: Systems in which incident light is modified in accordance with the properties of the material investigated (where the material investigated is optically excited causing a change in wavelength of the incident light G01N21/63) - G01N 21/15: Preventing contamination of the components of the optical system or obstruction of the light path - G01N 21/94: Investigating contamination, e.g. dust (G01N21/85 takes precedence) - G01N 21/53: within a flowing fluid, e.g. smoke - G01N 2021/157: {Monitoring by optical means} - G01N 2021/945: {Liquid or solid deposits of macroscopic size on surfaces, e.g. drops, films, or clustered contaminants} - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) ## Abstract An environmental sensor is disclosed. The environmental sensor includes a semiconductor substrate including a light sensor, a surface through which ambient light can pass to reach a light sensor and a light source operable to illuminate the surface, whereby at least some of the light from the light source is reflected by the surface onto the light sensor. The environmental sensor is operable to determine the presence of a fouling layer on the surface by comparing measurements of ambient light and reflected light by the at least one light sensor. ## Claims ### Claim 1 An environmental sensor comprising: a semiconductor substrate including a light sensor; a surface through which ambient light can pass to reach a light sensor, and a light source operable to illuminate the surface, whereby at least some of the light from the light source is reflected by the surface onto the light sensor, wherein the environmental sensor is operable to determine the presence of a fouling layer on the surface by comparing measurements of ambient light and reflected light by the at least one light sensor. ### Claim 2 (depends on 1) The environmental sensor of claim 1 comprising at least one further type of sensor. ### Claim 3 (depends on 1) The environmental sensor of claim 1, wherein the light sensor and the light source are integrated in a common semiconductor substrate. ### Claim 4 (depends on 1) The environmental sensor of claim 1, wherein the light sensor, the light source and the further sensor are each integrated on a common substrate, wherein the at least one further sensor is located in a first region of the substrate and the light source and light sensor are located in a second region of the substrate, wherein the second region is shielded from the environment by the surface, and wherein the first region is exposed to the environment. ### Claim 5 (depends on 1) The environmental sensor of claim 1, in which the light source is an LED device. ### Claim 6 (depends on 1) The environmental sensor of claim 1, operable to analyse a frequency spectrum of the received light to differentiate between different kinds of ambient light sources. ### Claim 7 (depends on 1) The environmental sensor of claim 1, wherein the surface comprises a window in a package of the environmental sensor. ### Claim 8 (depends on 1) The environmental sensor of claim 1, wherein the surface comprises a material deposited on the semiconductor substrate. ### Claim 9 (depends on 8) The environmental sensor of claim 8, wherein the material deposited on the semiconductor substrate comprises silicon nitride, silicon oxynitride or silicon dioxide. ### Claim 10 (depends on 1) An environmental management system comprising at least one environmental sensor according to claim 1. ### Claim 11 A method of operating an environmental sensor comprising a semiconductor substrate including a light sensor, a surface through which ambient light can pass to reach the light sensor, and a light source operable to illuminate the surface, whereby at least some of the light from the light source is reflected by the surface onto the light sensor, the method comprising: determining the presence of a fouling layer on the surface by comparing measurements of ambient light and reflected light by the light sensor. ### Claim 12 (depends on 11) The method of claim 11 further comprising: making a first measurement comprising measuring the intensity of the ambient light that passes the surface whereas the light source is turned off; and making a second measurement comprising measuring the intensity of the light reaching the light sensor whereas the light source is turned on; and subtracting the first measured intensity from the second measured intensity; and using the result of the subtraction to determine the intensity of the reflected light. ### Claim 13 (depends on 11) The method of claim 11 comprising measuring the intensity by a light sensor of light from the light source reflected by the surface, on which no fouling layer is present, in the absence of ambient light, for use as a calibrated light intensity characteristic for a clean transparent surface. ### Claim 14 (depends on 11) The method of claim 11, comprising analysing a frequency spectrum of the received light to differentiate between different kinds of ambient light sources. ### Claim 15 (depends on 11) The method of claim 11, comprising using the frequency characteristics of the ambient light and the reflected light to determine a structure or thickness of the fouling layer.