Film sensors array and method

In accordance with an embodiment, sensor structure has a first, second, and third laminated structures. The second laminated structure is positioned between the first laminated structure and the third laminated structure. The first laminated structure includes a first portion of a first sensing element and the third laminated structure includes a second portion of the first sensing element. The second laminated structure includes spacer elements that can be used to adjust the sensitivity of the sensor structure.

FIELD OF THE INVENTION

The present invention relates, in general, to electronics and, more particularly, to electronics in combination with fluids.

BACKGROUND

In the past, sensors have been used in a variety of applications including, but not limited to, sensing moisture, humidity, sound, temperature, light, gases, chemicals, magnetic fields, electrical currents, voltages, fluid flow, liquid volume, concentrations of solutes in liquids, tire pressure, biological materials in a liquid sample, and physical stresses. Most sensors are discrete elements designed to sense a particular parameter. A discrete sensor is mounted to a rigid structure such as a printed circuit. Depending on the application, other devices such as, for example, discrete switches, control devices, and heat removal structures, may be mounted on the rigid structure along with the discrete sensor. The heat removal structures may be cooling fins that are coupled to the power devices, wherein the heat removal structures are mounted to a separate structure from the structure on which the power device is mounted. Because of the number of discrete components used to make up an electronic system is large, these systems tend to be bulky, heavy, and expensive to manufacture.

By way of example, a pressure sensor is typically a discrete sensor that is mounted to a printed circuit board. The pressure sensor may be made up of a thin layer of stainless steel that has two strain gauges attached along two of its axes. Pressure is indirectly measured by deforming the thin stainless steel layer where the bending changes the ohmic resistance of the attached strain gauges by less than 0.1 percent. The change in ohmic resistance is determined using a Wheatstone bridge. The accuracy of the measurement depends on the thickness of the stainless steel layer, the accuracy of the resistors of the Wheatstone bridge, temperature coefficients of the components making up the pressure sensor, etc. If the sensor is configured as an array of sensors, the accuracy of the measurement is also dependent on the distance between the sensors. Drawbacks with pressure sensors mounted to printed circuit boards include their size and the weight of the strain gauges.

Thus, a sensor structure capable of sensing more than a single parameter includes a plurality of sensors. For example, to measure temperature, humidity, and pressure, three discrete sensors are mounted to a rigid structure such as a printed circuit board and electrically connected to sensory electronics that are also mounted to the printed circuit board.

Another class of discrete sensors are bio-sensors. These types of sensors may be used to monitor a component of blood, such as blood glucose. A drawback with these types of sensors is that the analytes, reactants, and by-products in the sensors must be purged and removed before the sensors can be re-used.

Accordingly, it would be advantageous to have sensors or sensor structures capable of providing continuous monitoring, that can monitor one or more parameters, that are light weight, and portable, and that can be purged and reused. It would be of further advantage for the semiconductor components, sensing elements, electronics, sensors, power devices, etc. and the methods of sensing and manufacturing of the sensors to be cost and time efficient to implement.

For simplicity and clarity of illustration, elements in the figures are not necessarily to scale, and the same reference characters in different figures denote the same elements. Additionally, descriptions and details of well-known steps and elements are omitted for simplicity of the description. It will be appreciated by those skilled in the art that the words during, while, and when as used herein are not exact terms that mean an action takes place instantly upon an initiating action but that there may be some small but reasonable delay, such as a propagation delay, between the reaction that is initiated by the initial action and the initial action. The use of the words approximately, about, or substantially means that a value of an element has a parameter that is expected to be very close to a stated value or position. However, as is well known in the art there are always minor variances that prevent the values or positions from being exactly as stated. It is well established in the art that variances of up to about ten per cent (10%) (and up to twenty per cent (20%) for semiconductor doping concentrations) are regarded as reasonable variances from the ideal goal of being exactly as described.

DETAILED DESCRIPTION

FIG. 1is a block diagram of sensing unit10in accordance with an embodiment of the present invention. Sensing unit10includes a switching structure12connected to a power source14, one or more power devices15, and to sensing circuitry16. Switching structure12is configured to open and close in response to a physical stress such as, for example, being pressed by a finger, a shipping box, a dog's nose, electronically controlled switches, etc. In response to an external stimulus such as, for example, being pressed, switching structure12closes connecting power source14to sensing circuitry16, which generates an output signal indicating, for example, the location being pressed, the force pressing against the sensor, or both. Although switching structure12is described as including a pressure sensor, this is not a limitation of the present invention.

It should be noted that in accordance with embodiments in which sensing structures are formed from film electronics, at least switching structure12and sensing circuits16can be manufactured from a single film. Switching structure12can be configured to switch one or more sensors and/or one or more power devices simultaneously. In accordance with another embodiment, multiple sensors can be combined with multiple drive circuits to open a door, shift weight in a bed to lessen the probability of bed sores being formed, to move an arm, etc.

In accordance with another embodiment, sensors, switching circuits, switching structures, drive circuits, power devices, and heat dissipation devices can be configured on a film to conduct heat from the circuitry and through the films making up the thin films on which the sensors, switching circuit, drive devices, and/or power electronics are mounted. In addition, film electronics can be configured to rapidly remove heat or spread heat using fluids including a gas, water, other fluids, etc. Gases, fluids, electromagnetic fields, electromagnetic energy, sounds, vibrations, and chemicals can pass next to, into or through film electronics where sensing circuits, power devices and switching structures are embedded. Proximity of film sensors to analytes is achieved while separating sensitive film electronics from damaging effects of analytes, chemicals, fluids, temperatures, and noises.

FIG. 2is a top view of a film sensor array12in accordance with an embodiment of the present invention. Film sensor array12may be referred to as a sensing unit, sensor unit, sensor architecture, switches, or the like. More particularly,FIG. 2illustrates an array of 256 sensing elements. By way of example, the size of the array shown inFIG. 2is 4 inches by 4 inches. Film sensor array12may be comprised of a plurality of film layers or laminated film structures in a stacked configuration. By way of example, film sensor array12may include three stacked laminated film structures, where a laminated film structure12B (shown inFIG. 6) is between or separates laminated film structures12A and12C. Laminated film structure12A and a portion of laminated film structure12C are shown inFIG. 2. For the sake of completeness,FIG. 3is included to show a top view of laminated film structure12A.

FIGS. 2 and 3further illustrate electrically conductive structures56A,56B,56C, and56D within switching elements30. Switching elements30and electrically conductive structures are further described with reference toFIG. 5. In accordance with embodiments in which switching elements30are configured as pressure sensors, different portions of a switching element may respond to a different pressure created by for example, a finger pressing on switching element30. For example, a portion of switching element30having electrically conductive structure56A may respond to a higher pressure than a portion of switching element30having electrically conductive structure56B, which may respond to a higher pressure than a portion of switching element30having electrically conductive structure56C, which may respond to a higher pressure than a portion of switching element30having electrically conductive structure56D. Thus, the different portions of switching elements30may be configured to have a different sensitivity to pressure.

FIG. 4is an exploded top view of the portion of the laminated film structure12A ofFIGS. 2 and 3bounded by broken line5inFIGS. 2 and 3.FIG. 4further illustrates electrically conductive portion56A of switching element301, electrically conductive portion56B of switching element302, and vias60.

FIG. 5is a cross-sectional view of a portion of film sensor array12taken along section line5-5ofFIGS. 2 and 3. What is shown inFIG. 5are switching elements30in accordance with an embodiment of the present invention. For the sake of clarity portions of two switching elements of the plurality of switching elements30are illustrated inFIG. 5and are identified by reference characters301and302. It should be noted that in the embodiment shown inFIGS. 2-5, switching elements30, e.g., switching elements301and302, are fabricated as a bendable or foldable structure comprising three structures12A,12B, and12C. More particularly, switching elements30may be comprised of a structure12B which is located or positioned between structures12A and12C. Structure12B has openings34A and34B, surfaces36, and surfaces38. By way of example, structure12B is polyimide having a thickness ranging from about 0.25 mils to about 10 mils, structure12A is a laminated film structure having a thickness ranging from about 0.5 mils to about 6 mils, and structure12C is a laminated film structure having a thickness ranging from about 0.5 mils to about 6 mils. Other suitable materials for structure12B include liquid crystal polymer, a film adhesive, silicone, paper, polyethylene, polystyrene, aluminum foil, magnetic steel foil, stainless steel foils, thermal interface film, polytetrafluoroethylene, which may be sold under the tradename Teflon, and the like. Alternatively, structure12B can be a laminated structure. The thicknesses of structures12A,12B, and12C are not limitations of the present invention. By way of example, laminated film structures12A and12C may be formed from an insulated metal substrate such as, for example, a double bonded copper substrate. As those skilled in the art are aware a mil is approximately 25.4 micrometers.

In accordance with an embodiment, laminated film structure12A may be a metal-insulator-metal substrate, comprising a film50having surfaces52and54and an electrically conductive material formed on surface52and an electrically conductive material formed on surface54. Suitable materials for film50include liquid crystal polymer, a film adhesive, silicone, paper, polyethylene, polystyrene, aluminum foil, magnetic steel foil, stainless steel foils, thermal interface film, polytetrafluoroethylene, which may be sold under the tradename Teflon, and the like. By way of example, electrically conductive structures56and58are made from one ounce copper. The thicknesses of structure12B and film50are not limitations of the present invention.

Vias60are formed in portions of laminated film substrate12A, wherein vias60extend through laminated film structure12A. A plated electrically conductive material57electrically connects electrically conductive structure56B to electrically conductive structure58B and electrically conductive structure56A to electrically conductive structure56B. After formation of vias60, portions of the electrically conductive material on surface52of film50are removed to form electrically conductive structures56A and56B on surface52and portions of the electrically conductive material on surface54are removed to form electrically conductive structures58A and58B. Layers of an electrically conductive material59are formed on electrically conductive structures58A and58B. Electrically conductive layers59may be formed by electroplating. By way of example, electrically conductive layer59is a metallization system comprising nickel, palladium, and gold, where the nickel is electroplated on the electrically conductive material of electrically conductive structures58A and58B, palladium is electroplated on the nickel, and gold is electroplated on the palladium.

A film62is disposed on surface52and electrically conductive structures56A and56B and a film64is formed on portions of surface54. Film64is laterally spaced apart from electrically conductive portions58A and58B. Portions of film64are bonded to laminated film structure12A. Suitable materials for layers62and64include liquid crystal polymer, film adhesive, silicone, paper, polyethylene, polystyrene, photo-imageable polyimide, aluminum foil, magnetic steel foil, stainless steel foils, thermal interface film, polytetrafluoroethylene, which may be sold under the tradename Teflon, and the like. The thicknesses of material layer34, film50, film70are not limitations of the present invention.

In accordance with an embodiment, laminated film structure12C is a metal-insulator-metal substrate, comprising a film70having surfaces72and74, an electrically conductive material formed on surface72to form electrically conductive structures76A and76B, and an electrically conductive material formed on surface74that is patterned to form electrically conductive structures78A and78B. Suitable materials for film70include polyimide, liquid crystal polymer, a film adhesive, silicone, paper, polyethylene, polystyrene, a thermal interface film, polytetrafluoroethylene, which may be sold under the tradename Teflon, and the like. By way of example, electrically conductive structures76A,76B,78A and78B are made from one ounce copper. The thicknesses of film50and film70, and the electrically conductive materials from which electrically conductive structures76A,76B,78A, and78B are manufactured are not limitations of the present invention.

Vias80are formed in portions of laminated film substrate12C, wherein vias80extend through laminated film structure12C. After formation of vias80, portions of the electrically conductive material on surface72of film70are removed to form electrically conductive structures76A and76B on surface72and portions of the electrically conductive material on surface74are removed to form electrically conductive structures78A and78B. Layers of an electrically conductive material79are formed on electrically conductive structures78A and78B. Electrically conductive layers79may be formed by electroplating. By way of example, electrically conductive layer79is a metallization system comprising nickel, palladium, and gold, where the nickel is electroplated on the electrically conductive material of electrically conductive structures76A and76B, palladium is electroplated on the nickel, and gold is electroplated on the palladium.

A film82is disposed on surface72and electrically conductive portions76A and76B and a film84is formed on portions of surface74. Film82is laterally spaced apart from electrically conductive structures76A and76B. Portions of film84are bonded to laminated film structure12C. Suitable materials for layers82and84include polyimide, liquid crystal polymer, a film adhesive, silicone, paper, polyethylene, polystyrene, photo-imageable polyimide, a thermal interface film, polytetrafluoroethylene, which may be sold under the tradename Teflon, and the like. The thicknesses of laminated film structure12C, film82, and film84are not limitations of the present invention.

It should be noted that electrically conductive structure56A is electrically connected to electrically conductive structure58A by plated electrically conductive material57, electrically conductive structure56B is electrically connected to electrically conductive structure58B by plated electrically conductive material57, electrically conductive structure76A is electrically connected to electrically conductive structure78B by plated electrically conductive material77, and electrically conductive structure76A is electrically connected to electrically conductive structure78A by plated electrically conductive material77. By way of example, electrically conductive portions57and77are metallization systems comprising nickel, palladium, and gold, where the nickel is electroplated on the exposed portions of electrically conductive structures56A,56B,58A,58B,76A,76B,78A, and78B, palladium is electroplated on the nickel, and gold is electroplated on the palladium.

Laminated film structure12A is positioned above surface36of structure12B and laminated film structure12C is positioned below surface38of structure12B. Alternatively, an adhesive material can be used to bond surfaces35and38to structure12B.

FIG. 6is a top view of a portion of structure12B ofFIG. 5in accordance with an embodiment of the present invention. It should be appreciated that structure12B is between structures12A and12C and is therefore not visible inFIG. 2.FIG. 6further illustrates openings34A and34B that are shown inFIG. 5.

FIG. 7is an exploded top view of the portion of structure12B bounded by broken line box7ofFIG. 6. More particularly,FIG. 7shows portions12B1,12B2, and12B3of structure12B. Portions12B1,12B2, and12B3may be referred to as spacer elements. In the embodiment shown inFIG. 7, spacer element12B1is spaced apart from or separated from spacer element12B2by a distance D2and spacer element12B2is spaced apart from or separated from spacer element12B3by a distance D1. It should be noted that an opening34A is between spacer elements12B2and12B3and an opening34B is between spacer elements12B1and12B2. In accordance with the embodiment shown inFIGS. 5 and 7, distance D1is less than distance D2, i.e., distance D2is greater than distance D1. The pressure sensitivity of switching elements or sensing elements30, e.g., sensing elements301and302, can be tuned by adjusting the thickness of structure12B, adjusting the distance between spacer elements such as spacer elements12B1and12B2, and adjusting the distance between spacer elements12B2and12B3. It should be appreciated that pressure sensitivity can be tuned by adjusting the thicknesses and distances either individually or adjusting a combination of one or more of the parameters.FIG. 7further illustrates that in this embodiment distance D1of opening34A is less than distance D2of opening34B, where openings34A and34B have been described with reference toFIG. 5.

FIG. 8is a top view of laminated film structure12C in accordance with an embodiment of the present invention. What is shown inFIG. 8are electrically conductive structures76A and76B of sensing elements30, portions of fluid sensors92, and portions of temperature sensors94. Thus, in accordance with an embodiment, pressure sensors30, fluid sensors92and temperature sensors94are integrated into a flexible sensing structure. It should be noted that other types of sensors can be integrated into the flexible sensing structure including inductive coils95, capacitive sensing elements93, resistive sensing elements96, or the like.

FIG. 9is an exploded top view of the portion of the laminated film structure12C bounded by broken line9ofFIG. 8.FIG. 9further shows electrically conductive portions76A of switching element301, electrically conductive portions76B of switching element302, and vias80. It should be noted that vias80are positioned to be laterally shifted from vias60. For the sake of completeness, the location of sensing elements301and302are pointed out.

FIGS. 10-19illustrate a cross-sectional view of a film power device100fabricated from a flexible substrate and configured to include a fluid cooling structure in accordance with another embodiment of the present invention. What is shown inFIG. 10is a cross-sectional view of a support substrate102of film power device100at a beginning stage of manufacture. Support substrate102has a surface104and a surface106. By way of example, support substrate102is a polyimide film sold under the trademark Kapton® and has a thickness of about 5 mils. A high temperature adhesive layer108is formed on surface104and a high temperature adhesive layer110is formed on surface106. Suitable materials for adhesive layers108and110include but are not limited to, polyimide, polybenzimadole, their co-polymers, and the like. An electrically conductive material112such as, for example, a one ounce copper foil is formed on adhesive layer108and an electrically conductive material118, such as, for example, a one ounce copper foil is formed on adhesive layer110. Support substrate102, adhesive layers108and110, and electrically conductive material112and118form a support structure114. Although the material for electrically conductive materials112and118has been described as being copper, this is not a limitation. Other suitable materials include conductive carbon, graphite, or cuprates such as, for example, Bi2Sr2Ca2Cu3O10(BSCCO), or the like.

Still referring toFIG. 10, an opening116having a dimension W1is formed in support structure114using, for example, a router. For the sake of clarity, reference characters114A and114B have been used to identify portions of support structure114after formation of opening116. It should be understood that after formation of opening116, portions114A and114B of support substrate114are still connected as a single film through other portions of support structure114. A portion of copper foil118is removed using, for example, a router to form an opening120that exposes portions of adhesive layer110. It should be noted that opening120exposes portions of adhesive layer110of portions114A and114B of support structure114. In accordance with an example, opening120has a dimension W2that is greater than dimension W1, wherein openings116and120have a center point at approximately the same horizontal location.

Referring now toFIG. 12, a masking structure130is formed on electrically conductive material112. Masking structure130has openings130A and130B that expose vias124A and124B and portions of electrically conductive material112adjacent vias124A and124B, respectively. A masking structure132is formed on electrically conductive material118. Masking structure132has openings132A and132B that expose vias124A and124B and portions of electrically conductive material118adjacent vias124A and124B, respectively. An electrically conductive material134is formed along the exposed edges of support substrate102in portion114A of support structure114and an electrically conductive material136is formed along the exposed edges of support substrate102in portion114B of support structure114. By way of example, electrically conductive material134and136is copper formed using an electroplating technique. It should be noted that the electrically conductive material is also plated onto the portions of electrically conductive material112and118adjacent to vias124A and124B that are unprotected by masking structures130and132to increase the thickness of the electrically conductive material in these regions.

Referring now toFIG. 14, a masking structure140having masking elements142and openings144is formed on electrically conductive material112, opening116, and vias124A and124B. Openings144expose portions of electrically conductive layer112. A masking structure146having masking elements148and openings150is formed on electrically conductive layer118and may cover opening116. Openings150expose portions of copper foil118. The portions of copper foil112exposed by openings144are removed to expose portions of adhesive layer108and the portions of copper foil118exposed by openings150are removed to expose portions of adhesive layer110.

Referring now toFIG. 16, a layer of glass160having a thickness of, for example, 2 mils is placed over adhesive layer110to cover opening116and an adhesive layer162having a thickness of, for example, 2 mils is formed over electrically conductive material118and portions of glass layer160. A polyimide film164is formed on adhesive layer162. By way of example, polyimide film164is a film sold under the trademark Kapton® and has a thickness of 1 mil. Alternatively, layer160may be a thermally conductive, electrically insulating material such as aluminum nitride, alumina, silicon carbide, silicon, etc. It should be noted that layer160may have a solderable copper layer so that a solder die attach material can be used instead of an epoxy die attachment material.

Referring now toFIG. 17, an adhesive layer172having a thickness of, for example, 2 mils is formed on polyimide layer164and over glass layer160. It should be noted that adhesive layer172is spaced apart from glass layer160to form a channel176. Adhesive layer172forms channels177over adhesive layer110. Channels177may be capillary sized channels. A polyimide layer180having a thickness of, for example, 1 mil, is formed on adhesive layer172. In accordance with an embodiment, adhesive layer172and polyimide layer180may form a film and adhesive layer168and polyimide layer178may form a film.

An adhesive layer168having a thickness of, for example, 1 mil is formed over electrically conductive material112, over the portions of adhesive layer108that are exposed, and over vias124A and124B. A polyimide layer178having a thickness of, for example, 1 mil, is formed on adhesive layer168. Like adhesive layer172and polyimide layer180, adhesive layer168and polyimide layer172may form a film.

Referring now toFIG. 18, an electrically conductive material175is formed on the exposed portions of electrically conductive material112. By way of example, electrically conductive material175is comprised of a nickel, palladium, gold metallization system in which nickel is electroplated on the exposed portion of electrically conductive material112, palladium is electroplated on the nickel, and gold is electroplated on the palladium. This combination of metals allows gold ball bonding. A cut line184may be formed through support structure114. Alternatively, the film electronics may also be drilled and singulated.

Referring now toFIG. 19, a conductive adhesive190is formed on glass layer160. A semiconductor chip192is bonded to glass layer160through conductive adhesive190. In accordance with an embodiment, a Metal Oxide Semiconductor Field Effect Transistor (MOSFET) is formed from semiconductor chip192. Semiconductor chip192includes a drain that is electrically coupled to electrically conductive materials112and175through a bonding wire or wirebond194in portion114A of electrically conductive structure114and a source that is electrically coupled to electrically conductive materials112and175through a bonding wire or wirebond195in portion114B of support structure114. For the sake of completeness,FIG. 19further illustrates a portion of a bonding wire or wirebond196that is bonded to a gate of semiconductor chip192. A protective material198such as, for example, silicone, or glob-top may be dispensed over wirebonds194,195, and196and semiconductor chip192to protect them from environmental stresses. Protective material198may be referred to as a protective encapsulant material or an encapsulant material. Integrated fluid channel176is positioned next to glass layer160to rapidly conduct and convect heat away from semiconductor chip192. Additional capillary fluid channels177are positioned within film electronic module100to spread, conduct, and convect heat to or away from other devices embedded inside film electronic module100. It should be noted that the cooling fluid passing through fluid channels176and177can be fluids in liquid form or fluids in gaseous form. Suitable liquid fluids include water, 100% ethylene glycol, acetic acid, n-nonane, styrene, n-butyl alcohol, or the like, or combinations thereof. In addition, additives may be included.

FIG. 20illustrates a cross-sectional view of a film power device200fabricated from a flexible substrate and configured to include a fluid cooling structure in accordance with another embodiment of the present invention. Film power device200is similar to film power device100except that channels177, adhesive layer172, and polyimide layer180are absent from film power device200. Channels177are replaced by channels210A and218A within cooling structures201. Layers172and180of film power device100have been replaced by anodized materials202,214, and220, and adhesive layers208and216. Channels176are replaced with a thermally conductive grease199that is between glass layer160and aluminum202. In accordance with an embodiment, cooling structure201is comprised of an aluminum foil214bonded to aluminum foil202using strips of adhesive material208. Cooling structure201may be referred to as an aluminum cooling radiator. Narrow channels210A and a wide channel210are formed between aluminum foil214and aluminum foil202. Adhesive strips208are laterally spaced apart to form channel210as a wide channel and to form channels210A as narrower channels compared to channel210. Aluminum foil214is bonded to anodized aluminum foil220using adhesive strips216. Capillary channels218A are formed between adhesive strips216and between aluminum foil214and anodized aluminum foil220. Adhesive strips216are laterally spaced apart from each other to form capillary channels218A.

Still referring toFIG. 20, adhesive strips208are positioned so that channel210is formed between aluminum foil202and aluminum foil214that is larger than channels210A and are aligned with semiconductor chip192, glass layer160, and thermally conductive grease199. By way of example, adhesive strips208and216are 1 mil thick, aluminum foil214is 5 mils thick and aluminum foils202and220are 11 mils thick. Aluminum foils202and220and anodized aluminum foil220cooperate to form an aluminum casing.

In operation, a cooling fluid such as, for example, water flows through channels210,210A, and218A to spread or to remove heat generated by semiconductor chip192and other electronic circuits that may be coupled to semiconductor chip192. Capillary channels210A and218A may help pull the cooling fluid through them.

Channels210,210A, and218A are intended to be filled with fluid, vacuum pumped down to evacuate air and other volatile gases and then the edges of the aluminum are welded to seal the fluid and its vapor inside and to create a partial vacuum. Channels210,210A, and218A allow a tiny amount of fluid trapped inside them to vaporize 100% without bloating its thin aluminum casing. The narrow channels, thin adhesives, a partial pressure of the fluid prevent the thinned out aluminum casing from collapsing during vacuum pump down.

It should be noted that film power electronics such as, for example film power electronics200may be a module that includes many semiconductor chips and related drive circuits integrated with and embedded in laminated films. The laminated film separates the high voltage electronics embedded in the films from liquid or other fluids that serve as heat radiators. Power film modules such as power film module200can bend and conform to the curvature of an aluminum cooling radiator201that can also bend to a desired shape. A common aluminum cooling radiator201can be used by all circuits and thermal generators associated with the film power electronic structure such as film power electronic structure200. Fluid cooled systems in accordance with embodiments of the present invention are bendable and light weight because of the low volume of fluid within them. For example, 0.5 grams of water inside a one liter volume of a vacuum sealed cooling structure380can be used to cool a 10,000 Watt film power inverter module.

FIG. 21is a view of a cooling structure380in accordance with an embodiment of the present invention. It should be noted that cooling structure380may be comprised of cooling structure21ofFIG. 20. What is shown inFIG. 21are cooling channels210and210A configured for spreading and removing heat from four semiconductor chips such as, for example, semiconductor chip192shown inFIG. 19orFIG. 20. The aluminum radiator allows water to vaporize into steam identified by reference character382which subsequently vents from channels210. The heat of vaporization is 540 calories per gram of water (for embodiments in which the fluid is water) which provides a 1,700 times increase in the volume of water that turns into steam. The large volume of steam inside an aluminum radiator condenses on large aluminum surface areas and returns to be re-used as cooling water384in a vacuum sealed aluminum casing386. Water is pulled in through capillary channels210A along entry holes388or through capillary channels218A. The heat capacity of water is 1 calorie per gram to raise the temperature by one degree Celsius. Thus, 540 calories are needed to vaporize 1 gram of water into steam. Cooling structure380allows building a cooling structure that uses less water and has a lighter weight because the cooling structure can be manufactured in view of the heat of vaporization of water as well as water's heat capacity to transport, convect, and conduct heat.

FIG. 22illustrates a cross-sectional view of a multi-function sensor300in accordance with an embodiment of the present invention. More particularly,FIG. 22illustrates a sensor configured to monitor an optical signal and a fluid, i.e., an optical sensor and a fluid sensor integrated into a single film. Thus, multi-function sensor300includes an optical fiber302and a single lumen plastic tube304that are inserted or formed between polyimide films306and308and laterally spaced apart from a light source310. By way of example, light source310is a light emitting diode (LED) Integrating multiple sensor functions into a single sensor allows more than a single parameter to be sensed. For example, multi-function sensor300may be used to measure the size and number of red blood cells in a blood sample. Optical fiber302and light source310can be configured to count the number and estimate the size of each of the red blood cells passing by optical fiber302and light source310. Light source310may be a silicon based semiconductor die having a surface310A and a surface310B, wherein surface310B may include a polyimide passivation layer, gold plated pad310D over aluminum bond pad, and fluorescence activating nano-rods.

Multi-function sensor300includes optical fiber302having a refractive index η1formed within and extending from a cladding320having a refractive index η2, where refractive index η1is greater than refractive index η2. Cladding320has a surface322and a surface324. Tubing304has an exterior surface304A, an exterior surface304B, and a channel304C. As those skilled in the art appreciate, cladding320may be comprised of a single layer of material or a plurality of layers of material.

Multi-function sensor300includes a support structure328on which light source310is mounted. By way of example, support structure328is comprised of a copper film330having a protrusion330C. An adhesive film304is formed on a bottom surface and a polyimide film308is formed on adhesive film304.

Light source310is coupled to copper film330by a thermally conductive die attach material334. A protective material is formed over portions of copper layer330and thermally conductive die attach material334. Support structure328is attached to adhesive303and polyimide306by a layer that is not visible inFIG. 21because it is off-plane inFIG. 21(the layer that is not visible may be a laminate film structure having a thickness ranging from about 160 micrometers to about 300 micrometers.

Multi-function sensor300further includes a film structure348that covers chamber358and layers, wire bond pads, and bond wires that are connected to light source310. Multi-function film sensor has multiple ports where tubing304, optical fiber320, and other tubing (not shown) can be inserted. By way of example, support structure348is comprised of a polyimide film306and polyimide film308that protect the components ofFIG. 21.

Tube304, optical fiber302and cladding320are inserted into film structure348. Film structure348is bonded to surfaces320A of cladding320and to surfaces304A of tubing304by adhesive materials340and350. Adhesive materials340and350can be silicone. Tubing304, cladding320, adhesive materials340and350, and support structure328cooperate to form a sealed cavity358.

FIG. 23is a top view of a film fluid monitor400connected to a power supply and other electronic circuitry housed in cabinet or box402and connected to a vertical elevation bladder404. Film monitor400includes a film substrate410. Integrated electronic component and circuits412and a chamber414are embedded inside film substrate410. Integrated electronic component and circuits412may include circuitry configured to sense and compensate for temperature, pressure, humidity, and flow rates. Integrated electronic component and circuits412are positioned or located close to chamber414, for example 150 micrometers or less. Inlet ports or inlet holes422are connected to chamber414through inlet channels420. Chamber414may include other sensory devices configured to analyze one or more fluids flowing into inlet ports420though inlet channels422and into chamber414. By way of example, inlet channels420are formed between two adhesive films and have dimensions of 20 mils by 12 mils. An analyte fluid droplet placed on any one of the inlet ports422of inlet channels420is drawn through inlet channels420and into chamber414for analysis. Capillary action pulls the fluid inside film substrate410through channels represented by broken lines428.

Film fluid monitor400further includes an inlet channel429connected to an inlet port409. A tube304such as, for example, a single lumen tube is inserted into inlet portion409and coupled to inlet channels429and sealed with an adhesive680. By way of example, tube304connects a fluid storage structure or fluid bladder404that may contain a purging fluid and an enzyme indicated by reference character406. Fluid storage structure404may be raised, lowered, or completely shut-off with a valve to regulate the flow of purging fluid from fluid storage structure404into chamber414though inlet channels429. Outlet channels428allows fluid to flow out from chamber414through exhaust ports427.

A carbon heater coil430has an end432coupled to an electrically conductive pad434and an end436coupled to an electrically conductive pad438. By way of example, carbon heater coil430is embedded inside film substrate410and positioned to be above outlet channels428. Suitable materials for electrically conductive pads434and438include copper, aluminum, plated copper, or the like. It should be noted that copper pads434are connected to copper pads438by copper traces to film electronics412that include a transistor to turn-on or turn-off carbon heater430depending on a temperature sensor embedded in film electronic412. MOSFETs and heater coils are two types of power devices15. Conductive pads434and438allow current to pass from copper lines (not shown) through carbon heater coil430. The degree of heating is regulated by an electrical current, a fluid flow rate, and temperature sensor circuits embedded that are part of integrated electronic circuits412that are embedded in film substrate410. Integrated electronic circuits412are electrically connected to a power supply and to other circuits that reside in box402. A film to film connector403is electrically and mechanically connected to film substrate410. As discussed above, the fluid flow rate can be regulated by adjusting the vertical elevation of fluid storage structure404relative to inlet channels420and relative to the height of outlet portions427. Fluid can flow through the channels by capillary action plus the effect of gravity. Film substrate410bends and/or tilts to change the elevation of inlets relative to outlets to adjust the flow of analyte fluid from inlet ports422into chamber414. Electronic sensing and regulation of the fluid flow rate out of chamber414through outlet channels428is accelerated through heat assisted evaporation of fluids by heater coil430and integrated electronic circuits75.FIG. 23illustrates an embodiment in which the integration of plastic tubing304, liquid fluids, fluid channels, embedded electronics412, sensing circuit16, switching structure12, and power devices15ofFIG. 1are all embedded inside film substrate410. Film substrate410can be translucent or transparent to visible or infra-red light. The color of fluids and gas bubbles passing through channels428and429can be visually seen or detected by film electronics412under channels428and429.

Those skilled in the art will realize that inductor coils and/or carbon resistors can be fabricated in a configuration similar to heater coil430. Inductor coils consisting of a fine carbon line with many turns coiling along a top plane of film substrate410may be connected by a copper pad with a copper via to a bottom film layer of film substrate410with carbon line coils along the bottom plane of film substrate410to create a continuous inductor coil with a greater inductance value than two separated coils of the same surface area on a single plane. A fine carbon line, coil or serpentine line allows one to create higher resistance carbon resistors in or on film substrate410. A Ultraviolet laser can be used to trim a carbon resistor to a desired resistor value, if needed. In addition, a printed carbon line can be added to selectively short adjacent copper pads in order to adjust the circuitry of selected circuits of electronic component and circuits412to add or increase capacitance, trim adjacent coils of an inductor coil, or to trim an inductance value, or to short devices of electronic component and circuits412. In addition, a heater coil such as, for example, coil430can be embedded around chamber413to warm the fluid, the transducer device, and the enzyme to make the reactions more efficient.

In accordance with an embodiment, light emitting devices604are comprised of bare blue light emitting diodes that transmit optical signals having wavelengths ranging from about 445 nanometers to about 455 nanometers. Those skilled in the art realize that each protein or bio-molecule has a characteristic peak light absorption range of wavelengths. Light emitting diodes are produced that emit different wavelengths from blue to infrared wavelengths over 2,000 nanometers. The choice of light emitting diode and its brightness depends upon the molecule of interest and the penetration depth of light into tissue.

In operation, film substrate602and cotton cloth610are folded around an ear along a fold axis24-24. Blue light emitting diodes604A and604B pulse light capable of penetrating into living tissues including ear lobes and plant leaves. Light emitted from light emitting diodes604A and604B causes human skin, blood, and tissues under the skin to fluoresce or re-emit light. Fluorescent light differs from the original light signal by having a longer wavelength and the color of the emitted light depends on the molecules, and bio-materials such as proteins and carbohydrates that are fluorescing. Sweat, for example, flows into holes614and black cotton cloth610absorbs stray light and sweat. In addition, cotton from black cotton cloth610absorbs, spreads, and evaporates moisture to enhance comfort in fastening film sensors to an ear lobe.

Light sensors606A and606B detect reflected light at two different wavelengths and are located on the same side as light emitting diodes604A and604B, respectively, and are configured to sense sweat from skin by a change in light intensity and noise caused by stray light, motion, and other sources. Thermistor608monitors skin temperature. Fluorescing light passes through blood vessels, tissues, and skin to the opposite side of an ear lobe where light sensors606are located, wherein light sensors606detect transmitted, refracted, and reflected light of predetermined wavelengths. Pulsing light emitting diodes604A and604B may be off during detection. Those skilled in the art realize that film fluid monitor600can be used to check food, trace chemicals, or contaminants in water.

FIG. 25is a view of a hat650on which a battery power supply652, sensor circuitry654, which may include light emitting diode pulse circuitry and sensor circuits, a microcontroller656, a micro-SD card memory658, and other circuitry such as filters, an analog-to-digital converter, a wireless antenna, and communications circuitry are mounted. A film sensor660, which may be, for example, film sensor600ofFIG. 24, is coupled to sensor circuit654and microcontroller656through wires or interconnects662. Alarm devices664such as, for example, light emitting diodes or a buzzer, are mounted to hat650.

FIG. 26is a view of a manufacturing flow to form electronics in a film in accordance with an embodiment of the present invention. What is shown inFIG. 26is a processing system700that includes an ink jet printer head702, a scanning light laser704, a hardmask706, a chromium metal comb patterning structure708, and film spools710and712. Film spools710and712are configured for providing film substrate716for processing and then collecting film substrate716after processing.

Film electronics720including etched copper lines and copper pads722are formed on film substrate716and film substrate716is wound onto film spool710. Film substrate716is placed in processing system700for further processing. Processing system700selectively prints conductive carbon ink with moving ink printer head702to deposit rows of overlapping thin conductive photo-sensitive ink730on copper pads722and between copper pads722. Multiple deposition passes are performed adjacent to the edges of copper pads722to thicken the ink creating a beveled surface with ink. The ink transitions to become thinner over film substrate716between two copper pads722. A heater hot plate (not shown) is positioned under film substrate716to soft bake photo-sensitive ink730after conductive carbon ink730has been printed. Film substrate716travels in the direction indicated by arrow734.

In a subsequent step, processing system700places chrome hardmask706in proximity to film substrate716and hardmask706is aligned to cross fiducial marks (not shown) on film substrate716. Processing system700exposes photo-sensitive ink730to ultraviolet light from scanning light laser704through chromium metal comb pattern708on hard mask706. Exposure to the intense laser vaporizes carbon and breaks cross-linked macromolecules that bind carbon particles, leaving interdigitated fingers736of carbon lines between copper pads722. Spray head718dispenses an adhesive coating such as, for example, silicone over carbon fingers736and copper pads722. A hot plate (not shown) under film716cures the adhesive cover.

FIG. 27is a cross-sectional view of a portion of film sensor array12-1taken along section line5-5ofFIGS. 2 and 3in accordance with another embodiment of the present invention. The description ofFIG. 27is similar to the description of sensor array12ofFIG. 5, except that spacer elements12B1,12B2, and12B3have been replaced by spacer elements12B1A,12B2A, and12B3A, respectively. Spacer element12B1A has a height that is greater than the height of spacer element12B2A and spacer element12B2A has a height that is greater than the height of spacer element12B3A, i.e., the height of spacer12B2A is less than the height of spacer12B1A and spacer12B3A has a height that is less than the height of spacer12B2A. It should be noted that the heights of spacers12B1A,12B2A, and12B3A can be referred to as the thicknesses of spacers12B1A,12B2A, and12B3A.

By now it should be appreciated that a sensor unit and methods for sensing have been provided. Electronics shrink further after integration of power MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) with conducting lines made from thinner conductor or high temperature superconducting materials such as cuprates, for example, Bi2SrCa2Cu3O10(BSCCO). Those skilled in the art realize there are many materials and many ways to deposit film onto a film substrate besides 3D printing as shown inFIG. 26. Sputtering, pulse laser deposition, electrophoretic deposition, etc. are alternate deposition methods. Another variant in accordance with embodiments of the present invention is that laser source704ofFIG. 26may be adapted, configured, and used to anneal the surface film conductors or cuprates to avoid overheating the polyimide substrate716. Spray coating may represent spray cleaning or spray etching.FIG. 26represents one of many ways to deposit materials, process as roll-to-roll film, clean, heat, coat, and stabilize the desired characteristics of material for the purpose of mass producing film electronics inexpensively, rapidly, and consistently. A variety of materials such as, but not limited to, nano-rod fluorescence, graphene or graphite, carbon nanotubes, whiskers between biased electrodes, insulating and semiconducting glasses may likewise be selectively and sequentially processed in the roll-to-roll format ofFIG. 26. The manufacturing line700can be carried out in an air ambient, under vacuum and/or portions of the manufacturing line700submerged under fluid.

Although specific embodiments have been disclosed herein, it is not intended that the invention be limited to the disclosed embodiments. Those skilled in the art will recognize that modifications and variations can be made without departing from the spirit of the invention. It is intended that the invention encompass all such modifications and variations as fall within the scope of the appended claims.