Fabrication methods for bio-compatible devices

A method may involve: forming a first bio-compatible layer; forming a conductive pattern on the first bio-compatible layer, wherein the conductive pattern defines an antenna, sensor electrodes, electrical contacts, and one or more electrical interconnects; forming a protective layer over the sensor electrodes, such that the sensor electrodes are covered by the protective layer; mounting an electronic component to the electrical contacts; forming a second bio-compatible layer over the first bio-compatible layer, the electronic component, the antenna, the protective layer, the electrical contacts, and the one or more electrical interconnects; removing a portion of the second bio-compatible layer to form an opening in the second bio-compatible layer; and removing the protective layer through the opening in the second bio-compatible layer to thereby expose the sensor electrodes.

BACKGROUND

A body-mountable device may be configured to monitor health-related information based on at least one analyte from a user. For example, a bio-compatible device may be embedded in a polymer to provide the body-mountable device. The bio-compatible device includes a sensor configured to detect the at least one analyte (e.g., glucose) in a fluid of a user wearing the body-mountable device. The body-mountable device may also be configured to monitor various other types of health-related information.

SUMMARY

In one aspect, a method involves: forming a first bio-compatible layer, wherein the first bio-compatible layer defines a first side of a bio-compatible device; forming a conductive pattern on the first bio-compatible layer, wherein the conductive pattern defines an antenna, sensor electrodes, electrical contacts, and one or more electrical interconnects; forming a protective layer over the sensor electrodes, such that the sensor electrodes are covered by the protective layer; mounting an electronic component to the electrical contacts; forming a second bio-compatible layer over the first bio-compatible layer, the electronic component, the antenna, the protective layer, the electrical contacts, and the one or more electrical interconnects, wherein the second bio-compatible layer defines a second side of the bio-compatible device; removing a portion of the second bio-compatible layer to form an opening in the second bio-compatible layer; and removing the protective layer through the opening in the second bio-compatible layer to thereby expose the sensor electrodes.

In another aspect, a device is disclosed. The device includes: a conductive pattern, wherein the conductive pattern defines an antenna, sensor electrodes, electrical contacts, and one or more electrical interconnects; a protective layer over the sensor electrodes, such that the sensor electrodes are covered by the protective layer; an electronic component mounted to the electrical contacts; and a bio-compatible layer over the electronic component, the antenna, the protective layer, the electrical contacts, and the one or more electrical interconnects, such that the antenna, the protective layer, the electrical contacts, and the one or more electrical interconnects are covered by the bio-compatible layer, wherein the bio-compatible layer defines a first side and a second side of a bio-compatible device.

In yet another aspect, a system is disclosed. The system includes: means for forming a first bio-compatible layer, wherein the first bio-compatible layer defines a first side of a bio-compatible device; means for forming a conductive pattern on the first bio-compatible layer, wherein the conductive pattern defines an antenna, sensor electrodes, electrical contacts, and one or more electrical interconnects; means for forming a protective layer over the sensor electrodes, such that the sensor electrodes are covered by the protective layer; means for mounting an electronic component to the electrical contacts; means for forming a second bio-compatible layer over the first bio-compatible layer, the electronic component, the antenna, the protective layer, the electrical contacts, and the one or more electrical interconnects, wherein the second bio-compatible layer defines a second side of the bio-compatible device; means for removing a portion of the second bio-compatible layer to form an opening in the second bio-compatible layer; and means for removing the protective layer through the opening in the second bio-compatible layer to thereby expose the sensor electrodes.

DETAILED DESCRIPTION

The following detailed description describes various features and functions of the disclosed methods and systems with reference to the accompanying figures. In the figures, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative method and system embodiments described herein are not meant to be limiting. It will be readily understood that certain aspects of the disclosed methods and systems can be arranged and combined in a wide variety of different configurations, all of which are contemplated herein.

Disclosed herein are bio-compatible devices and methods for fabricating a bio-compatible device. Once fabricated, the bio-compatible device could be surrounded by a polymer to provide a body-mountable device. Beneficially, the bio-compatible devices and methods for fabricating a bio-compatible device disclosed herein can be used in scenarios when the body-mountable device comprises a variety of mountable devices that are mounted on or in portions of the human body, such as an eye-mountable device, a tooth-mountable device, and/or a skin-mountable device.

II. EXAMPLE SYSTEMS AND DEVICES

An example body-mountable device that comprises an eye-mountable device that is configured to detect at least one analyte in a tear film of a user wearing the eye-mountable device will now be described in greater detail.

FIG. 1is a block diagram of a system100that includes an eye-mountable device110in wireless communication with an external reader120. The eye-mountable device110may be a polymeric material that may be appropriately shaped for mounting to a corneal surface and in which a structure is at least partially embedded. The structure may include a power supply140, a controller150, bio-interactive electronics160, and an antenna170.

In some embodiments, the structure may be a bio-compatible device in which some or all of the components formed or mounted thereon are encapsulated by a bio-compatible material.

In some example embodiments, the structure may be positioned away from the center of the eye-mountable device110and thereby avoid interference with light transmission to the central, light-sensitive region of the eye. For example, where the eye-mountable device110is shaped as a curved disk, the structure may be embedded around the periphery (e.g., near the outer circumference) of the disk. In other example embodiments, the structure may be positioned in or near the central region of the eye-mountable device110. For example, portions of the structure may be substantially transparent to incoming visible light to mitigate interference with light transmission to the eye. Moreover, in some embodiments, the bio-interactive electronics160may include a pixel array164that emits and/or transmits light to be received by the eye according to display instructions. Thus, the bio-interactive electronics160may optionally be positioned in the center of the eye-mountable device so as to generate visual cues perceivable to a wearer of the eye-mountable device110, such as displaying information (e.g., characters, symbols, flashing patterns, etc.) on the pixel array164.

The power supply140is configured to harvest ambient energy to power the controller150and bio-interactive electronics160, and may include an energy harvesting antenna142and/or solar cells144. The energy harvesting antenna142may capture energy from incident radio radiation. The solar cells144may comprise photovoltaic cells configured to capture energy from incoming ultraviolet, visible, and/or infrared radiation.

A rectifier/regulator146may be used to condition the captured energy to a stable DC supply voltage141at a level suitable for operating the controller, and then supply the voltage to the controller150. The rectifier/regulator146may include one or more energy storage devices to mitigate high frequency variations in the energy harvesting antenna142and/or solar cell(s)144. For example, one or more energy storage devices (e.g., a capacitor or an inductor) may be connected in parallel across the outputs of the rectifier/regulator146to regulate the DC supply voltage141and may be configured to function as a low-pass filter.

The controller150is configured to execute instructions to operate the bio-interactive electronics160and the antenna170. The controller150includes logic circuitry configured to operate the bio-interactive electronics160so as to interact with a biological environment of the eye-mountable device110. The interaction could involve the use of one or more components, such an analyte bio-sensor162in the bio-interactive electronics160, to obtain input from the biological environment. Additionally or alternatively, the interaction could involve the use of one or more components, such as a pixel array164, to provide an output to the biological environment.

In one example, the controller150includes a sensor interface module152that is configured to operate the analyte bio-sensor162. The analyte bio-sensor162may be, for example, an amperometric electrochemical sensor that includes a working electrode and a reference electrode driven by a sensor interface. A voltage is applied between the working and reference electrodes to cause an analyte to undergo an electrochemical reaction (e.g., a reduction and/or oxidation reaction) at the working electrode. The electrochemical reaction generates an amperometric current that can be measured through the working electrode. The amperometric current can be dependent on the analyte concentration. Thus, the amount of the amperometric current that is measured through the working electrode can provide an indication of analyte concentration. In some embodiments, the sensor interface module152can be a potentiostat configured to apply a voltage difference between working and reference electrodes while measuring a current through the working electrode.

In some instances, a reagent may also be included to sensitize the electrochemical sensor to one or more desired analytes. For example, a layer of glucose oxidase (“GOD”) proximal to the working electrode can catalyze glucose oxidation to generate hydrogen peroxide (H2O2). The hydrogen peroxide can then be electro-oxidized at the working electrode, which releases electrons to the working electrode, resulting in an amperometric current that can be measured through the working electrode.

The current generated by either reduction or oxidation reactions is approximately proportionate to the reaction rate. Further, the reaction rate is dependent on the rate of analyte molecules reaching the electrochemical sensor electrodes to fuel the reduction or oxidation reactions, either directly or catalytically through a reagent. In a steady state, where analyte molecules diffuse to the electrochemical sensor electrodes from a sampled region at approximately the same rate that additional analyte molecules diffuse to the sampled region from surrounding regions, the reaction rate is approximately proportionate to the concentration of the analyte molecules. The current measured through the working electrode thus provides an indication of the analyte concentration.

The controller150may also include a display driver module154for operating a pixel array164. The pixel array164is an array of separately programmable light transmitting, light reflecting, and/or light emitting pixels arranged in rows and columns. The individual pixel circuits can optionally include liquid crystal technologies, microelectromechanical technologies, emissive diode technologies, etc. to selectively transmit, reflect, and/or emit light according to information from the display driver module154. Such a pixel array164may also include more than one color of pixels (e.g., red, green, and blue pixels) to render visual content in color. The display driver module154can include, for example, one or more data lines providing programming information to the separately programmed pixels in the pixel array164and one or more addressing lines for setting groups of pixels to receive such programming information. Such a pixel array164situated on the eye can also include one or more lenses to direct light from the pixel array to a focal plane perceivable by the eye.

The controller150may also include a communication circuit156for sending and/or receiving information via the antenna170. The communication circuit156may include one or more oscillators, mixers, frequency injectors, or the like to modulate and/or demodulate information on a carrier frequency to be transmitted and/or received by the antenna170. In some example embodiments, the eye-mountable device110is configured to indicate an output from a bio-sensor by modulating an impedance of the antenna170in a manner that is perceivable by the external reader120. For example, the communication circuit156can cause variations in the amplitude, phase, and/or frequency of backscatter radiation from the antenna170, and such variations may then be detected by the reader120.

It is noted that the block diagram shown inFIG. 1is described in connection with functional modules for convenience in description. However, embodiments of the eye-mountable device110can be arranged with one or more of the functional modules (“sub-systems”) implemented in a single chip, integrated circuit, and/or physical component.

Additionally or alternatively, the energy harvesting antenna142and the antenna170can be implemented in the same, dual-purpose antenna. For example, a loop antenna can both harvest incident radiation for power generation and communicate information via backscatter radiation.

The external reader120includes an antenna128(or group of more than one antennae) to send and receive wireless signals171to and from the eye-mountable device110. The external reader120also includes a computing system with a processor126in communication with a memory122. The memory122is a non-transitory computer-readable medium that can include, without limitation, magnetic disks, optical disks, organic memory, and/or any other volatile (e.g., RAM) or non-volatile (e.g., ROM) storage system readable by the processor126. The memory122includes a data storage123to store indications of data, such as sensor readings (e.g., from the analyte bio-sensor162), program settings (e.g., to adjust behavior of the eye-mountable device110and/or external reader120), etc. The memory122also includes program instructions124for execution by the processor126. For example, the program instructions124may cause the external reader120to provide a user interface that allows for retrieving information communicated from the eye-mountable device110(e.g., sensor outputs from the analyte bio-sensor162). The external reader120may also include one or more hardware components for operating the antenna128to send and receive the wireless signals171to and from the eye-mountable device110. For example, oscillators, frequency injectors, encoders, decoders, amplifiers, and filters can drive the antenna128according to instructions from the processor126.

The external reader120may be a smart phone, digital assistant, or other portable computing device with wireless connectivity sufficient to provide the wireless communication link171. The external reader120may also be implemented as an antenna module that can be plugged in to a portable computing device, such as in an example where the communication link171operates at carrier frequencies not commonly employed in portable computing devices. In some instances, the external reader120is a special-purpose device configured to be worn relatively near a wearer's eye to allow the wireless communication link171to operate using little or low power. For example, the external reader120can be integrated in a piece of jewelry such as a necklace, earing, etc. or integrated in an article of clothing worn near the head, such as a hat, headband, etc.

In an example where the eye-mountable device110includes an analyte bio-sensor162, the system100can be operated to monitor the analyte concentration in tear film on the surface of the eye. To perform a reading with the system100configured as a tear film analyte monitor, the external reader120can emit radio frequency radiation171that is harvested to power the eye-mountable device110via the power supply140. Radio frequency electrical signals captured by the energy harvesting antenna142(and/or the antenna170) are rectified and/or regulated in the rectifier/regulator146and a regulated DC supply voltage141is provided to the controller150. The radio frequency radiation171thus turns on the electronic components within the eye-mountable device110. Once turned on, the controller150operates the analyte bio-sensor162to measure an analyte concentration level. For example, the sensor interface module152can apply a voltage between a working electrode and a reference electrode in the analyte bio-sensor162. The applied voltage can be sufficient to cause the analyte to undergo an electrochemical reaction at the working electrode and thereby generate an amperometric current that can be measured through the working electrode. The measured amperometric current can provide the sensor reading (“result”) indicative of the analyte concentration. The controller150can operate the antenna170to communicate the sensor reading back to the external reader120(e.g., via the communication circuit156).

In some embodiments, the system100can operate to non-continuously (“intermittently”) supply energy to the eye-mountable device110to power the controller150and electronics160. For example, radio frequency radiation171can be supplied to power the eye-mountable device110long enough to carry out a tear film analyte concentration measurement and communicate the results. For example, the supplied radio frequency radiation can provide sufficient power to apply a potential between a working electrode and a reference electrode sufficient to induce electrochemical reactions at the working electrode, measure the resulting amperometric current, and modulate the antenna impedance to adjust the backscatter radiation in a manner indicative of the measured amperometric current. In such an example, the supplied radio frequency radiation171can be considered an interrogation signal from the external reader120to the eye-mountable device110to request a measurement. By periodically interrogating the eye-mountable device110(e.g., by supplying radio frequency radiation171to temporarily turn the device on) and storing the sensor results (e.g., via the data storage123), the external reader120can accumulate a set of analyte concentration measurements over time without continuously powering the eye-mountable device110.

FIG. 2ais a top view of an eye-mountable device210.FIG. 2bis side view of the eye-mountable device210. It is noted that relative dimensions inFIGS. 2aand 2bare not necessarily to scale, but have been rendered for purposes of explanation only in describing the arrangement of the eye-mountable device210.

The eye-mountable device210may include a polymeric material220, which may be a substantially transparent material to allow incident light to be transmitted to the eye. The polymeric material220may include one or more bio-compatible materials similar to those employed to form vision correction and/or cosmetic contact lenses in optometry, such as polyethylene terephthalate (“PET”), polymethyl methacrylate (“PMMA”), polyhydroxyethylmethacrylate (“polyHEMA”), silicone hydrogels, or any combinations of these. Other polymeric materials may also be envisioned. The polymeric material220may include materials configured to moisturize the corneal surface, such as hydrogels and the like. In some embodiments, the polymeric material220is a deformable (“non-rigid”) material to enhance wearer comfort.

To facilitate contact-mounting, the eye-mountable device210may comprise a concave surface226configured to adhere (“mount”) to a moistened corneal surface (e.g., by capillary forces with a tear film coating the corneal surface). While mounted with the concave surface against the eye, a convex surface224of eye-mountable device210is formed so as not to interfere with eye-lid motion while the eye-mountable device210is mounted to the eye. A circular outer side edge228connects the concave surface224and the convex surface226. The convex surface224can therefore be considered an outer, top surface of the eye-mountable device210whereas the concave surface226can be considered an inner, bottom surface. The “top” view shown inFIG. 2ais facing the convex surface224.

The eye-mountable device210can have dimensions similar to a vision correction and/or cosmetic contact lenses, such as a diameter of approximately 1 centimeter, and a thickness of about 0.1 to about 0.5 millimeters. However, the diameter and thickness values are provided for explanatory purposes only. In some embodiments, the dimensions of the eye-mountable device210may be selected according to the size and/or shape of the corneal surface and/or the scleral surface of the wearer's eye. In some embodiments, the eye-mountable device210is shaped to provide a predetermined, vision-correcting optical power, such as provided by a prescription contact lens.

A structure230is embedded in the eye-mountable device210. The structure230can be embedded to be situated near or along an outer periphery222, away from a central region221. Such a position ensures that the structure230will not interfere with a wearer's vision when the eye-mountable device210is mounted on a wearer's eye, because it is positioned away from the central region221where incident light is transmitted to the light-sensing portions of the eye. Moreover, portions of the structure230can be formed of a transparent material to further mitigate effects on visual perception.

The structure230may be shaped as a flat, circular ring (e.g., a disk with a centered hole). The flat surface of the structure230(e.g., along the radial width) allows for mounting electronics such as chips (e.g., via flip-chip mounting) and for patterning conductive materials to form electrodes, antenna(e), and/or interconnections. The structure230and the polymeric material220may be approximately cylindrically symmetric about a common central axis. The structure230may have, for example, a diameter of about 10 millimeters, a radial width of about 1 millimeter (e.g., an outer radius 1 millimeter greater than an inner radius), and a thickness of about 50 micrometers. These dimensions are provided for example purposes only, and in no way limit this disclosure.

A loop antenna270, controller250, and bio-interactive electronics260are included in the structure230. The controller250may be a chip including logic elements configured to operate the bio-interactive electronics260and the loop antenna270. The controller250is electrically connected to the loop antenna270by interconnects257also situated on the structure230. Similarly, the controller250is electrically connected to the bio-interactive electronics260by an interconnect251. The interconnects251,257, the loop antenna270, and any conductive electrodes (e.g., for an electrochemical analyte bio-sensor, etc.) may be formed from any type of conductive material and may be patterned by any process that can be used for patterning such materials, such as deposition or photolithography, for example. The conductive materials patterned on the structure230may be, for example, gold, platinum, palladium, titanium, carbon, aluminum, copper, silver, silver-chloride, conductors formed from noble materials, metals, or any combinations of these materials. Other materials may also be envisioned.

The structure230may be a bio-compatible device in which some or all of the components are encapsulated by a bio-compatible material. In one example, the controller250, interconnects251,257, bio-interactive electronics260, and the loop antenna270are fully encapsulated by bio-compatible material, except for the sensor electrodes in the bio-interactive electronics260.

As shown inFIG. 2a, the bio-interactive electronics module260is on a side of the structure230facing the convex surface224. Where the bio-interactive electronics module260includes an analyte bio-sensor, for example, mounting such a bio-sensor on the structure230to be close to the convex surface224allows the bio-sensor to sense analyte that has diffused through convex surface224or has reached the bio-sensor through a channel in the convex surface224(FIGS. 2cand 2dshow a channel272).

The loop antenna270is a layer of conductive material patterned along the flat surface of the structure230to form a flat conductive ring. In some example embodiments, the loop antenna270does not form a complete loop. For example, the loop antenna270may include a cutout to allow room for the controller250and bio-interactive electronics260, as illustrated inFIG. 2a. However, in another example embodiment, the loop antenna270can be arranged as a continuous strip of conductive material that wraps entirely around the structure230one or more times. Interconnects between the ends of such a wound antenna (e.g., the antenna leads) can connect to the controller250in the structure230. In some embodiments, the loop antenna can include a plurality of conductive loops spaced apart from each other, such as three conductive loops, five conductive loops, nine conductive loops, etc. With such an arrangement, the polymeric material220may extend between adjacent conductive loops in the plurality of conductive loops.

FIG. 2cis a side cross-section view of the eye-mountable electronic device210mounted to a corneal surface284of an eye280.FIG. 2dis an enlarged partial view of the cross-section of the eye-mountable device shown inFIG. 2c. It is noted that relative dimensions inFIGS. 2cand 2dare not necessarily to scale, but have been rendered for purposes of explanation only in describing the arrangement of the eye-mountable device210. Some aspects are exaggerated to allow for illustration and to facilitate explanation.

The eye280includes a cornea282that is covered by bringing an upper eyelid286and a lower eyelid288together over the surface of the eye280. Incident light is received by the eye280through the cornea282, where light is optically directed to light sensing elements of the eye280to stimulate visual perception. The motion of the upper and lower eyelids286,288distributes a tear film across the exposed corneal surface284of the eye280. The tear film is an aqueous solution secreted by the lacrimal gland to protect and lubricate the eye280. When the eye-mountable device210is mounted in the eye280, the tear film coats both the concave and convex surfaces224,226, providing an inner layer290(along the concave surface226) and an outer layer292(along the convex surface224). The inner layer290on the corneal surface284also facilitates mounting the eye-mountable device210by capillary forces between the concave surface226and the corneal surface284. In some embodiments, the eye-mountable device210can also be held over the eye280in part by vacuum forces against the corneal surface284due to the curvature of the concave surface226. The tear film layers290,292may be about 10 micrometers in thickness and together account for about 10 microliters of fluid.

The tear film is in contact with the blood supply through capillaries in the structure of the eye and includes many biomarkers found in blood that are analyzed to diagnose health states of an individual. For example, tear film includes glucose, calcium, sodium, cholesterol, potassium, other biomarkers, etc. The biomarker concentrations in tear film can be systematically different than the corresponding concentrations of the biomarkers in the blood, but a relationship between the two concentration levels can be established to map tear film biomarker concentration values to blood concentration levels. For example, the tear film concentration of glucose can be established (e.g., empirically determined) to be approximately one tenth the corresponding blood glucose concentration. Although another ratio relationship and/or a non-ratio relationship may be used. Thus, measuring tear film analyte concentration levels provides a non-invasive technique for monitoring biomarker levels in comparison to blood sampling techniques performed by lancing a volume of blood to be analyzed outside a person's body.

As shown in the cross-sectional views inFIGS. 2cand 2d, the structure230can be inclined so as to be approximately parallel to the adjacent portion of the convex surface224. As described above, the structure230is a flattened ring with an inward-facing surface232(closer to the concave surface226of the polymeric material220) and an outward-facing surface234(closer to the convex surface224). The structure230can include electronic components and/or patterned conductive materials adjacent to either or both surfaces232,234.

As shown inFIG. 2d, the bio-interactive electronics260, the controller250, and the conductive interconnect251are located between the outward-facing surface234and the inward-facing surface632such that the bio-interactive electronics260are facing the convex surface224. With this arrangement, the bio-interactive electronics260can receive analyte concentrations in the tear film292through the channel272. However, in other examples, the bio-interactive electronics260may be mounted on the inward-facing surface232of the structure230such that the bio-interactive electronics260are facing the concave surface226.

While the body-mountable device has been described as comprising the eye-mountable device110and/or the eye-mountable device210, the body-mountable device could comprise other mountable devices that are mounted on or in other portions of the human body.

For example, in some embodiments, the body-mountable device may comprise a tooth-mountable device. In some embodiments, the tooth-mountable device may take the form of or be similar in form to the eye-mountable device110and/or the eye-mountable device210. For instance, the tooth-mountable device could include a polymeric material that is the same or similar to any of the polymeric materials described herein and a structure that is the same or similar to any of the structures described herein. With such an arrangement, the tooth-mountable device may be configured to detect at least one analyte in a fluid (e.g., saliva) of a user wearing the tooth-mountable device.

Moreover, in some embodiments, the body-mountable device may comprise a skin-mountable device. In some embodiments, the skin-mountable device may take the form of or be similar in form to the eye-mountable device110and/or the eye-mountable device210. For instance, the skin-mountable device could include a polymeric material that is the same or similar to any of the polymeric materials described herein and a structure that is the same or similar to any of the structures described herein. With such an arrangement, the skin-mountable device may be configured to detect at least one analyte in a fluid (e.g., perspiration, blood, etc.) of a user wearing the skin-mountable device.

Further, some embodiments may include privacy controls which may be automatically implemented or controlled by the wearer of a body-mountable device. For example, where a wearer's collected physiological parameter data and health state data are uploaded to a cloud computing network for trend analysis by a clinician, the data may be treated in one or more ways before it is stored or used, so that personally identifiable information is removed. For example, a user's identity may be treated so that no personally identifiable information can be determined for the user, or a user's geographic location may be generalized where location information is obtained (such as to a city, ZIP code, or state level), so that a particular location of a user cannot be determined.

Additionally or alternatively, wearers of a body-mountable device may be provided with an opportunity to control whether or how the device collects information about the wearer (e.g., information about a user's medical history, social actions or activities, profession, a user's preferences, or a user's current location), or to control how such information may be used. Thus, the wearer may have control over how information is collected about him or her and used by a clinician or physician or other user of the data. For example, a wearer may elect that data, such as health state and physiological parameters, collected from his or her device may only be used for generating an individual baseline and recommendations in response to collection and comparison of his or her own data and may not be used in generating a population baseline or for use in population correlation studies.

III. EXAMPLE METHODS

FIGS. 3a-qillustrate stages in a process for fabricating a bio-compatible device, such as a bio-compatible device300qshown inFIG. 3q. The illustrations shown inFIGS. 3a-qare generally shown in cross-sectional views to illustrate sequentially formed layers developed to create the bio-compatible device. The layers can be developed by microfabrication and/or manufacturing techniques such as, for example, electroplating, photolithography, deposition, and/or evaporation fabrication processes and the like. The various materials may be formed according to patterns using photoresists and/or masks to pattern materials in particular arrangements, such as to form wires, electrodes, electrical contacts, etc. Additionally, electroplating techniques may also be employed to coat an arrangement of electrodes with a metallic plating. For example, an arrangement of conductive material formed by a deposition and/or photolithography process can be plated with a metallic material to create a conductive structure with a desired thickness. However, the dimensions, including relative thicknesses, of the various layers illustrated and described in connection withFIGS. 3a-qto create a bio-compatible device are not illustrated to scale. Instead, the drawings inFIGS. 3a-qschematically illustrate the ordering of the various layers for purposes of explanation only.

FIG. 3aillustrates a working substrate302with a sacrificial metal layer304formed on the working substrate302to provide a partially-fabricated device300a. The working substrate302may be any flat surface on which the layers of the encapsulated electronics structure can be assembled. For example, the working substrate302may be a wafer (e.g., a silicon wafer) similar to those used in the fabrication of semiconductor devices and/or microelectronics.

In the illustrated example, the sacrificial metal layer304includes a first sacrificial metal layer306and a second sacrificial metal layer308. However, in other examples, the sacrificial metal layer304may include one metal layer or more than two metal layers, such as three metal layers, four metal layers, five metal layers, etc.

The first sacrificial metal layer306and/or the second sacrificial metal layer308may include a variety of metals. For example, the first sacrificial metal layer306may include titanium, and the second sacrificial metal layer308may include aluminum. With this arrangement, the first sacrificial layer306may adhere to the working substrate302, and the second sacrificial metal layer308may bond to a bio-compatible layer.

Moreover, the first sacrificial metal layer306and/or the second sacrificial metal layer308may have a variety of thicknesses. For example, the first sacrificial metal layer306may have a thickness between 15 to 30 nanometers, such as 30 nanometers. And the second sacrificial metal layer308may have a thickness between 100 to 400 nanometers, such as 200 nanometers. Other thicknesses for the first sacrificial metal layer306and/or the second sacrificial metal layer308are possible as well.

In an example, the sacrificial metal layer304may be formed on the working substrate302by a microfabrication process, such as evaporation. However, in other examples, the sacrificial metal layer304may be formed on the working substrate302by other microfabrication processes, such as sputtering. In some embodiments, the first sacrificial metal layer306may be formed over the working substrate302, and the second sacrificial metal layer308may be formed over the first sacrificial metal layer306.

Moreover, the working substrate302may be cleaned before forming the sacrificial metal layer304. The working substrate302may be cleaned in a variety of ways. For example, the working substrate302may be cleaned by soaking in a first fluid, rinsing with a second fluid, and drying with a gas. In some embodiments, the first fluid may include acetone. Moreover, in some embodiments, the second fluid may include isopropyl alcohol (IPA). Further, in some embodiments, the gas may include nitrogen. All of the rinsing described herein may be performed in a variety ways, such as soaking in a bath in a tank, an automated spray, manually via a squirt bottle, etc.

Further, the working substrate302may be baked before forming the sacrificial metal layer304. The working substrate302may be baked in a variety of ways. For example, the working substrate302may be baked at a temperature for a time period. In some embodiments, the temperature may be 90 degrees Celsius (C). Moreover, in some embodiments, the time period may be 2 minutes.

Further still, the working substrate302may be plasma cleaned before forming the sacrificial metal layer304. The working substrate302may be plasma cleaned in a variety of ways. For example, the working substrate302may be plasma cleaned at a power for a time period. In some embodiments, the power may be high. Moreover, in some embodiments, the time period may be 5 minutes.

As shown inFIG. 3b, a first bio-compatible layer310is formed on the sacrificial metal layer304to provide a partially-fabricated device300b. The first bio-compatible layer310defines a first side312of a bio-compatible device. That is, the first bio-compatible layer310defines an outer edge of the bio-compatible device.

The first bio-compatible layer310may include a variety of materials. For example, the first bio-compatible layer310may include a polymeric material such as SCS parylene-C (e.g., dichlorodi-p-xylylene), a polyethylene terephthalate (PET), a polydimethysiloxane (PDMS), other silicone elastomers, and/or another bio-compatible polymeric material. The term “bio-compatibility,” as used in this disclosure, refers generally to the ability of a material or device to co-exist with a biological host. Bio-compatible materials are generally those that do not bring about a host response (such as an immune response) that results in deleterious effects to either the biological host or the material. In addition to being bio-compatible, the first bio-compatible layer310may be an electrically insulating material to isolate encapsulated electronics from the surrounding environment (e.g., from current-carrying particles and/or fluids).

Moreover, the first bio-compatible layer310may have a variety of thicknesses. For ample the first bio-compatible layer310may have a thickness between 5 to 50 micrometers, such as 15 micrometers. Other thicknesses of the first bio-compatible layer310are possible as well.

In an example, the first bio-compatible layer310may be formed by a microfabrication process such as chemical vapor deposition, and provides a surface on which various components can be formed. The first bio-compatible layer310may be deposited onto the sacrificial metal layer304with a substantially uniform thickness such that a surface of the first bio-compatible layer310opposite the working substrate302forms a flat surface. In addition, the first bio-compatible layer310may have sufficient structural rigidity to be used as a substrate for assembling various components. In some embodiments, the first bio-compatible layer310may be a conformal coat. And as noted above, the second sacrificial metal layer308might bond to a bio-compatible layer, such as the first bio-compatible layer310.

In an example, equipment that forms the first bio-compatible layer310may be preheated for 1 hour before forming the first bio-compatible layer310. Moreover, in an example, 35 grams of a polymeric material may be used to form the first bio-compatible layer310.

Moreover, an adhesion promoter may be applied to the sacrificial metal layer304before the first bio-compatible layer310is formed. In some embodiments, the adhesion promoter may comprise 3-methacryloxypropyltrimethoxysilane. And in such embodiments, the adhesion promoter may be A174 sold by Specialty Coating Systems and/or Sigma Aldrich. Other adhesion promoters are possible as well.

The adhesion promoter may be applied in a variety of ways. For example, the adhesion promoter may be applied by spin coating at a rate, baking at a temperature for a first time period, rinsing with a fluid, and baking at the temperature for a second time period. In some embodiments, the rate may be 3000 rotations per minute (rpm). And in such embodiments, applying the adhesion promoter by spin coating may involve accelerating and/or decelerating the partially-fabricated device300aat a rate between 100 to 3000 rpm per second, such as 1000 to 1500 rpm per second. Moreover, in some embodiments, the temperature may be 90 degrees C. Further, in some embodiments, the first time period may be 2 minutes. Further still, in some embodiments, the fluid may include IPA. And, in some embodiments, the second time period may be 1 minute.

In another example, the adhesion promoter may be applied by soaking the partially-fabricated device300ain a mixture including the adhesion promoter for a first time period, air drying on a towel for a second time period, rinsing with one or more fluids, and drying with a gas. In some embodiments, the mixture may comprise 100 parts deionized water (DI water), 100 parts IPA, and 1 part the adhesion promoter. Moreover, in some embodiments, the mixture may settle for 2 hours before soaking the partially-fabricated device300ain the mixture. Further, in some embodiments, the first time period may be 30 minutes. Moreover, in some embodiments, the second time period may be 30 minutes. Further, in some embodiments, the one or more fluids may include IPA and DI water. And, in some embodiments, the gas may include nitrogen. In such an example, soaking the partially-fabricated device300ain a mixture including the adhesion promoter for the first time period, air drying on a towel for the second time period, rinsing with one or more fluids, and/or drying with the gas may occur at room temperature. Moreover, in such an example, applying the adhesion promoter may further involve baking the partially-fabricated device300aat a temperature for a time period. In some embodiments, the temperature may be 90 degrees C. Moreover, in some embodiments, the time period may be 2 minutes.

Moreover, the partially-fabricated device300amay be cleaned before applying the adhesion promoter to the sacrificial metal layer304. The partially-fabricated device300amay be cleaned in a variety of ways. For example, the partially-fabricated device300amay be cleaned by rinsing in a fluid, drying with a gas, and baking at a temperature for a time period. In some embodiments, the fluid may include IPA. Moreover, in some embodiments, the gas may include nitrogen. Further, in some embodiments, the temperature may be 90 degrees C. Further still, in some embodiments, the time period may be 2 minutes.

Further, the partially-fabricated device300amay be plasma cleaned before applying the adhesion promoter to the sacrificial metal layer304. The partially-fabricated device300amay be plasma cleaned in a variety of ways. For example, the partially-fabricated device300amay be plasma cleaned at a power for a time period. In some embodiments, the power may be high. Moreover, in some embodiments, the time period may be 5 minutes.

Next, a seed layer314is formed over the first bio-compatible layer310to provide a partially-fabricated device300c, as shown inFIG. 3c. Such a seed layer314can be used to adhere to both the first bio-compatible layer310, and any additional metal structure that is patterned over the seed layer314, as will be described below. For example, the seed layer314may include one or more materials that both adheres well to the first bio-compatible layer310and serves as a guide to electroplate the remainder of a metal structure that forms a component. In such an example, the seed layer314may include palladium and/or gold. In some embodiments, the seed layer314may include a palladium layer and a gold layer.

Moreover, the seed layer314may have a variety of thicknesses. For example, a palladium layer of the seed layer314may have a thickness between 20 to 30 nanometers, such as 30 nanometers. Moreover, a gold layer of the seed layer314may have a thickness of 100 nanometers. Other thicknesses of the seed layer314are possible as well.

In an example, the seed layer314may be formed by a microfabrication process such as evaporation. However, in other examples, the seed layer314may be formed by other microfabrication processes, such as sputtering. In some embodiments, a palladium layer of the seed layer314may be formed over the first bio-compatible layer310, and a gold layer of the seed layer314may be formed over the palladium layer of the seed layer314.

Moreover, the partially-fabricated device300bmay be cleaned before forming the seed layer314over the first bio-compatible layer310. The partially-fabricated device300bmay be cleaned in a variety of ways. For example, the partially-fabricated device300bmay be cleaned by soaking in a first fluid, rinsing in a second fluid, and drying with a gas. In some embodiments, the first fluid may include acetone. Moreover, in some embodiments, the second fluid may include IPA. Further, in some embodiments, the gas may include nitrogen.

Further, the partially-fabricated device300bmay be baked before forming the seed layer314over the first bio-compatible layer310. The partially-fabricated device300bmay be baked at a temperature for a time period. In some embodiments, the temperature may be 90 degrees C. Moreover, in some embodiments, the time period may be 5 minutes. Further, in some embodiments, the partially-fabricated device300bmay be baked on a hot plate. After the partially-fabricated device300bis baked, the partially-fabricated device300bmay be cooled to room temperature.

Further still, the partially-fabricated device300bmay be plasma cleaned before forming the seed layer314over the first bio-compatible layer310. With this arrangement, a surface311of the first bio-compatible layer310(as shown inFIG. 3b) may be roughened, such that adhesion of the seed layer314to the first bio-compatible layer310may be improved. The partially-fabricated device300bmay be plasma cleaned in a variety of ways. For example, the partially-fabricated device300bmay be plasma cleaned at a power for a time period. In some embodiments, the power may be high. Moreover, in some embodiments, the time period may be 5 minutes.

In another example, the surface311of the first bio-compatible layer may treated before forming the seed layer314. With this arrangement, the surface311of the first bio-compatible layer310may be roughened, such that adhesion of the seed layer314to the first bio-compatible layer310may be improved. The surface311may be treated in a variety of ways. For example, the surface311of the first bio-compatible layer310may be treated by etching using an inductively coupled plasma at a power for a time. In some embodiments, the inductively coupled plasma may include an oxygen plasma. Moreover, in some embodiments, the power may be 400 Watts (W) with a 300 W bias. Further, in some embodiments, the time period may be 1 to 3 minutes. Other plasmas and/or types of plasmas may be used as well, such as plasma asher, a reactive ion etcher, etc.

As shown inFIG. 3d, a first sacrificial layer316is formed over a portion318of the seed layer314to provide a partially-fabricated device300d. The first sacrificial layer316may include a variety of materials. For example, the first sacrificial layer316may include a photoresist layer, such as a photoresist layer comprising 2-ethoxyethyl acetate. In such an example, the first sacrificial layer316may be AZ4620® sold by Capital Scientific.

Moreover, the first sacrificial layer316may have a variety of thicknesses. For example, the first sacrificial layer316may have thicknesses of 5 micrometers. Other thicknesses of the first sacrificial layer316are possible as well.

In an example, the first sacrificial layer316may be formed over the portion318of the first bio-compatible layer310by spin coating and patterning.

The first sacrificial layer316may be spin coated in a variety of ways. For example, a material may be spin coated by placing the material on the partially-fabricated device300c, applying a spread cycle, applying a spin cycle, and applying a deceleration cycle.

In some embodiments, placing the material on the partially-fabricated device300cmay include pouring (or pipetting) the material onto the partially-fabricated device300c.

Moreover, in some embodiments, applying the spread cycle may include rotating the partially-fabricated device300cat a first rate for a first time period. And in such embodiments, the first rate may be 500 rpm. And in such embodiments, the first time period may be 8 seconds. With this arrangement, the material may be spread over the seed layer314. The spread cycle may further include accelerating the partially-fabricated device300cat a second rate for a second time period before rotating the partially-fabricated device300cat the first rate for the first time period. In some embodiments, the second rate may be 250 rpm per second. Moreover, in some embodiments, the second time period may be 2 seconds.

Further, in some embodiments, applying the spin cycle may include rotating the partially-fabricated device300cat a first rate for a first time period. And in such embodiments, the first rate may be 3000 rpm. And in such embodiments, the first time period may be 28 to 38 seconds. With this arrangement, the thickness of the first sacrificial layer316may be formed. The spin cycle may further include accelerating the partially-fabricated device300cat a second rate for a second time period before rotating the partially-fabricated device300cat the first rate for the first time period. In some embodiments, the second rate may be 1500 rpm per second. Moreover, in some embodiments, the second time period may be 2 seconds.

Further still, in some embodiments, applying the deceleration cycle comprises decelerating the partially-fabricated device300cat a rate for a time period. And in such embodiments, the rate may be 1500 rpm per second. And in such embodiments, the time period may be 2 seconds.

Moreover, in some embodiments, the partially-fabricated device300cmay be placed in a vacuum chuck before placing the material on the partially-fabricated device300c. And in such embodiments, the partially-fabricated device300cmay be removed from the vacuum chuck after applying the declaration cycle.

After the first sacrificial layer316is spin coated, the first sacrificial layer316may be baked before patterning. The first sacrificial layer316may be baked in a variety of ways. For example, the first sacrificial layer316may be baked at a temperature for a time period. In some embodiments, the temperature may be 90 degrees C. Moreover, in some embodiments, the time period may be 2 minutes. After the first sacrificial layer316is baked, the first sacrificial layer316may be cooled to room temperature.

In addition, the first sacrificial layer316may be patterned in a variety of ways. For example, a material may be patterned by exposing and developing. In such an example, the material may be exposed to light at an intensity for a first time period, and developed by soaking in a fluid for a second time period. In some embodiments, the light may be ultra violet light (UV light) that is generated by a mercury lamp. Moreover, in some embodiments, the intensity may be 16 to 19 milliwatts per centimeter (mW/cm2). Further, in some embodiments, the first time period may be 10 to 12 seconds. Moreover, in some embodiments, the fluid may comprise four parts DI water and one part a fluid comprising potassium borates. And in such embodiments, the fluid comprising potassium borates may be AZ® 400K Developer sold by AZ Electronics Materials. Further still, in some embodiments, the second time period may be about 1 minute.

Moreover, the partially-fabricated device300dmay be further processed after formation of the first sacrificial layer316over the portion318of the seed layer314. The partially-fabricated device300dmay be further processed in a variety of ways. For example, the partially-fabricated device300dmay be further processed by rinsing in a fluid, blow drying with a gas, and baking at a temperature for a time period. In some embodiments, the fluid may include DI water. Moreover, in some embodiments, the gas may include nitrogen. Further, in some embodiments, the temperature may be 90 degrees C. Further still, in some embodiments, the time period may be 30 minutes. After the first sacrificial layer316is further processed after formation of the first sacrificial layer316over the portion318of the seed layer314, the first sacrificial layer316may be cooled to room temperature.

Further, the partially-fabricated device300cmay be cleaned before forming the first sacrificial layer316over the portion318of the seed layer314. The partially-fabricated device300cmay be cleaned in a variety of ways. For example, the partially-fabricated device300cmay be cleaned by soaking in a first fluid, rinsing in a second fluid, and drying with a gas. In some embodiments, the first fluid may include acetone. Moreover, in some embodiments, the second fluid may include IPA. Further, in some embodiments, the gas may include nitrogen.

Further still, the partially-fabricated device300cmay be baked before forming the first sacrificial layer316over the portion318of the seed layer314. The partially-fabricated device300cmay be baked at a temperature for a time period. In some embodiments, the temperature may be 90 degrees C. Moreover, in some embodiments, the time period may be 2 minutes. Further, in some embodiments, the partially-fabricated device300cmay be baked on a hot plate. After the partially-fabricated device300cis baked, the partially-fabricated device300cmay be cooled to room temperature.

As shown inFIG. 3e, a first metal layer320is formed over exposed portions328of the seed layer314(i.e., the portions that are not covered by the first sacrificial layer316) to provide a partially-fabricated device300e. The first metal layer320defines components including an antenna322, electrical contacts324, and electrical interconnects326.

The first metal layer320may include a variety of conductive materials. For example, the first metal layer320may include one or more layers of platinum, silver, gold, palladium, titanium, copper, chromium, nickel, aluminum, other metals or conductive materials, and combinations thereof. In some embodiments, the first metal layer320may include a substantially transparent conductive material for at least some components (e.g., a material such as indium tin oxide). In an example, the first metal layer320may comprise one layer of gold.

Moreover, the first metal layer320may have a variety of thicknesses. For example, the first metal layer320may have a thickness between 6 to 10 micrometers, such as between 6 to 7 micrometers, 7 to 8 micrometers, or 9 to 10 micrometers. Other thicknesses of the first metal layer320are possible as well.

In an example, the first metal layer320may be formed by a microfabrication process such as electroplating. Other microfabrication processes for forming the first metal layer320are possible as well. The first metal layer320may be electroplated in a variety ways. For example, the first metal layer320may be electroplated in a bath at a current for a time period. In some embodiments, the current is 60 milliamps (mA). Moreover, in some embodiments, the time period is 60 to 75 minutes.

Moreover, the partially-fabricated device300dmay be plasma cleaned before forming the first metal layer320over the exposed portions328of the seed layer314. The partially-fabricated device300dmay be plasma cleaned in a variety of ways. For example, the partially-fabricated device300dmay be plasma cleaned at a power for a time period. In some embodiments, the power may be high. Moreover, in some embodiments, the time period may be 5 minutes.

Next, the first sacrificial layer316is removed and the portion318of the seed layer314is removed to provide a partially-fabricated device300f, as shown inFIG. 3f. In some embodiments, a gold layer of the portion318of the seed layer314and/or a palladium layer of the portion318of the seed layer314may be removed.

The first sacrificial layer316may be removed in a variety of ways. For example, the first sacrificial layer316may be removed by soaking in a first fluid for a time period, rinsing in a second fluid, and drying with a gas. In some embodiments, the first fluid may include acetone. Moreover, in some embodiments, the time period may be 2 minutes. Further, in some embodiments, the second fluid may include IPA. Further still, in some embodiments, the gas may include nitrogen. And, in an example, removal may further involve agitation during soaking in the first fluid.

In addition, the portion318of the seed layer314may be removed in a variety of ways. For example, the portion318of the seed layer314may be removed by wet etching. The gold layer of the portion318of the seed layer314may be wet etched in a variety of ways. For example, the gold layer of the portion318of the seed layer314may be wet etched for a time period at a temperature. In some embodiments, the time period may be between 1 to 2 minutes. Moreover, in some embodiments, the temperature may be room temperature. And, in some embodiments, removing the gold layer of the portion318of the seed layer314may involve agitation (e.g., constant agitation) during wet etching. After the gold layer of the portion318of the seed layer314is wet etched, removing the gold layer of the portion318of the seed layer314may involve rinsing in a fluid and drying with a gas. In some embodiments, the fluid may include DI water. Moreover, in some embodiments, the gas may include nitrogen.

Moreover, the palladium layer of the portion318of the seed layer314may be wet etched in a variety of ways. For example, the palladium layer of the portion318of the seed layer314may be wet etched for a time period at a temperature. In some embodiments, the time period may be 30 seconds. Moreover, in some embodiments, the temperature may be 70 degrees C. After the palladium layer of the portion318of the seed layer314is wet etched, removing the palladium layer of the portion318of the seed layer314may involve rinsing in a fluid and drying with a gas. In some embodiments, the fluid may include DI water. Moreover, in some embodiments, the gas may include nitrogen.

As shown inFIG. 3g, a second sacrificial layer330is formed over a portion332of the first bio-compatible layer310and a portion334the first metal layer320to provide a partially-fabricated device300g. The second sacrificial layer330may include a variety of materials. For example, the second sacrificial layer330may include one or more photoresist layers, such as one photoresist layer comprising 2-ethoxyethyl acetate. In such an example, the second sacrificial layer330may be AZ4620® sold by Capital Scientific. In another example, the second sacrificial layer330may include one photoresist layer comprising 1-methoxy-2-propanol acetate. In such an example, the second sacrificial layer330may be AZ nLOF 2070® sold by AZ Electronic Materials. In yet another example, the second sacrificial layer330may include one photoresist layer comprising cyclohexanone. In such an example, the second sacrificial layer330may be NR9-3000PY sold by Futurrex, Inc.

Moreover, the second sacrificial layer330may have a variety of thicknesses. For example, the second sacrificial layer330may have a thicknesses of 5 micrometers. Other thicknesses of the second sacrificial layer330are possible as well.

In an example, the second sacrificial layer330may be formed over the portion332of the first bio-compatible layer310and the portion334of the first metal layer320by spin coating and patterning.

The second sacrificial layer330may be spin coated in a variety of ways. For example, a material may be spin coated by placing the material on the partially-fabricated device300f, applying a spread cycle, applying a spin cycle, and applying a deceleration cycle.

In some embodiments, placing the material on the partially-fabricated device300fmay include pouring (or pipetting) the material onto the partially-fabricated device300f.

Moreover, in some embodiments, applying the spread cycle may include rotating the partially-fabricated device300fat a first rate for a first time period. And in such embodiments, the first rate may be 500 rpm. And in such embodiments, the first time period may be 8 seconds. With this arrangement, the material may be spread over the partially-fabricated device300f. The spread cycle may further include accelerating the partially-fabricated device300fat a second rate for a second time period before rotating the partially-fabricated device300fat the first rate for the first time period. In some embodiments, the second rate may be 250 rpm. Moreover, in some embodiments, the second time period may be 2 seconds.

Further, in some embodiments, applying the spin cycle may include rotating the partially-fabricated device300fat a first rate for a first time period. And in such embodiments, the first rate may be 3000 rpm. And in such embodiments, the first time period may be 28 to 38 seconds. With this arrangement, the thickness of the sacrificial layer316may be formed. The spin cycle may further include accelerating the partially-fabricated device300fat a second rate for a second time period before rotating the partially-fabricated device300fat the first rate for the first time period. In some embodiments, the second rate may be 1500 rpm per second. Moreover, in some embodiments, the second time period may be 2 seconds.

Further still, in some embodiments, applying the deceleration cycle comprises decelerating the partially-fabricated device300fat a rate for a time period. And in such embodiments, the rate may be 1500 rpm per second. And in such embodiments, the time period may be 2 seconds.

Moreover, in some embodiments, the partially-fabricated device300fmay be placed in a vacuum chuck before placing the material on the partially-fabricated device300f. And in such embodiments, the partially-fabricated device300fmay be removed from the vacuum chuck after applying the deceleration cycle.

After the second sacrificial layer330is spin coated, the second sacrificial layer330may be baked before patterning. The second sacrificial layer330may be baked in a variety of ways. For example, the second sacrificial layer330may be baked at a temperature for a time period. In some embodiments, the temperature may be 90 degrees C. Moreover, in some embodiments, the time period may be 2 minutes. After the second sacrificial layer330is baked, the second sacrificial layer330may be cooled to room temperature.

In addition, the second sacrificial layer330may be patterned in a variety of ways. For example, the material may be patterned by exposing and developing. In such an example, the material may be exposed to light at an intensity for a first time period, and developed by soaking in a fluid for a second time period. In some embodiments, the light may be ultra violet light (UV light) that is generated by a mercury lamp. Moreover, in some embodiments, the intensity may be the intensity may be 16 to 19 mW/cm2. Further, in some embodiments, the first time period may be 10 to 12 seconds. Moreover, in some embodiments, the fluid may comprise four parts DI and one part a fluid comprising potassium borates. And in such embodiments, the fluid comprising potassium borates may be AZ® 400K Developer sold by AZ Electronics Materials. Further still, in some embodiments, the second time period may be about 1 minute.

Moreover, the partially-fabricated device300gmay be further processed after formation of the second sacrificial metal layer330over the portion332of the first bio-compatible layer310and the portion334the first metal layer320. The partially-fabricated device300gmay be further processed in a variety of ways. For example, the partially-fabricated device300gmay be further processed by rinsing in a fluid, blow drying with a gas, and baking at a temperature for a time period. In some embodiments, the fluid may include DI water. Moreover, in some embodiments, the gas may include nitrogen. Further, in some embodiments, the temperature may be 90 degrees C. Further still, in some embodiments, the time period may be 30 minutes. After the second sacrificial layer330is processed after formation, the second sacrificial layer330may be cooled to room temperature.

Further, the partially-fabricated device300fmay be cleaned before forming the second sacrificial layer330over the portion332of the first bio-compatible layer310and the portion334of the first metal layer320. The partially-fabricated device300fmay be cleaned in a variety of ways. For example, the partially-fabricated device300fmay be cleaned by soaking in a first fluid, rinsing in a second fluid, and drying with a gas. In some embodiments, the first fluid may include acetone. Moreover, in some embodiments, the second fluid may include IPA. Further, in some embodiments, the gas may include nitrogen.

Further still, the partially-fabricated device300fmay be baked before forming the second sacrificial layer330over the portion332of the first bio-compatible layer310and the portion334of the first metal layer320. The partially-fabricated device300fmay be baked at a temperature for a time period. In some embodiments, the temperature may be 90 degrees C. Moreover, in some embodiments, the time period may be 2 minutes. Further, in some embodiments, the partially-fabricated device300fmay be baked on a hot plate. After the partially-fabricated device300fis baked, the partially-fabricated device300fmay be cooled to room temperature.

As shown inFIG. 3h, a second metal layer336is formed over exposed portions344of the first bio-compatible layer310and exposed portions346of the first metal layer320(i.e., the portions that are not covered by the second sacrificial layer330) to provide a partially-fabricated device300h. The second metal layer336defines electrical interconnects338and sensor electrodes340.

The second metal layer336may include a variety of conductive materials. For example, the second metal layer336may include one or more layers of platinum, silver, gold, palladium, titanium, copper, chromium, nickel, aluminum, other metals or conductive materials, and combinations thereof. In an example, the second metal layer may comprise a titanium layer, a palladium layer, and a platinum layer.

Moreover, the second metal layer336may have a variety of thicknesses. For example, a titanium layer of the second metal layer336may have a thickness between 10 to 50 nanometers, such as 30 nanometers; a palladium layer may of the second metal layer336may have a thickness between 10 to 50 nanometers, such as 30 nanometers; and a platinum layer of the second metal layer336may have a thickness between 50 to 300 nanometers, such as 100 or 120 nanometers. Other thicknesses of the second metal layer336are possible as well.

In an example, the second metal layer336may be formed by a microfabrication process such as sputtering. However, in other examples, the second metal layer336may be formed by other microfabrication processes such as evaporation. In some embodiments, a titanium layer of the second metal layer336may be formed over the exposed portions344of the first bio-compatible layer310and exposed portions346of the first metal layer320, a palladium layer of the second metal layer336may be formed over the titanium layer, and a platinum layer of the second metal layer336may be formed over the palladium layer.

Moreover, the partially-fabricated device300gmay be plasma cleaned before forming the second metal layer336over the exposed portions344of the first bio-compatible layer310and the exposed portions346of the first metal layer320. The partially-fabricated device300gmay be plasma cleaned in a variety of ways. For example, the partially-fabricated device300gmay be plasma cleaned at a power for a time period. In some embodiments, the power may be high. Moreover, in some embodiments, the time period may be 60 seconds.

Next, the second sacrificial layer330is removed to provide a partially-fabricated device300i, as shown inFIG. 3i. The second sacrificial layer330may be removed in a variety of ways. For example, the second sacrificial layer330may be removed by soaking in a first fluid for a first time period, rinsing in a second fluid, drying with a gas, and baking at a temperature for a second time period. In some embodiments, the first fluid may include acetone. Moreover, in some embodiments, the first time period may be 1 to 5 hours, such as 1 to 2 hours or 4 to 5 hours. Further, in some embodiments, the second fluid may include IPA. Further still, in some embodiments, the gas may include nitrogen. Moreover, in some embodiments, the temperature may be 90 degrees C. Further, in some embodiments, the second time period may be 5 minutes. And, in an example, removal may further involve sonication for a time period (e.g., 2 to 3 seconds) after soaking in the first fluid. For instance, in some embodiments, removal may involve sonication for the time period after soaking in the first fluid for 1 hour.

After the second sacrificial layer330is removed, the partially-fabricated device300imay be rinsed in a fluid, dried with a gas, and baked at a temperature for a time period. In some embodiments, the fluid may include IPA. Moreover, in some embodiments, the gas may include nitrogen. Further, in some embodiments, the temperature may be 90 degrees C. Further still, in some embodiments, the time period may be 5 minutes.

Together, the first metal layer320and the second metal layer336are a conductive pattern342. The conductive pattern342defines the antenna332, the electrical contacts324, the electrical interconnects326, the electrical interconnects338, and the sensor electrodes340.

As shown inFIG. 3j, a protective layer348is formed over the sensor electrodes340to provide a partially-fabricated device300j. The protective layer348may include a variety of materials. For example, the protective layer348may include one or more photoresist layers, such as one photoresist layer comprising 2-ethoxyethly acetate. In such an example, the protective layer348may be AZ6420® sold by Capital Scientific. However, in other examples, the protective layer348may include one or more layers of metal, such as aluminum.

Moreover, the protective layer348may have a variety of thicknesses. For example, the protective layer348may have a thickness of 40 micrometers. Other thicknesses of the protective layer348are possible as well.

In an example, the protective layer348may be formed over the sensor electrodes340by spin coating and patterning. However, in other examples, the protective layer348may be formed by microfabrication processes such as evaporation and/or sputtering.

The protective layer348may be spin coated in a variety of ways. For example, the protective layer348may be spin coated in steps. In such an example, a first step may involve placing a first material on the partially-fabricated device300i, applying a spread cycle, applying a spin cycle, and applying a deceleration cycle.

In some embodiments, placing the first material on the partially-fabricated device300imay include pouring (or pipetting) the first material onto the partially-fabricated device300i.

Moreover, in some embodiments, applying the spread cycle may include rotating the partially-fabricated device300iat a first rate for a first time period. And in such embodiments, the first rate may be 500 rpm. And in such embodiments, the first time period may be 5 to 8 seconds. With this arrangement, the first material may be spread over the sensor electrodes340. The spread cycle may further include accelerating the partially-fabricated device300iat a second rate for a second time period before rotating the partially-fabricated device300iat the first rate for the first time period. In some embodiments, the second rate may be 100 to 250 rpm per second. Moreover, in some embodiments, the second time period may be 2 to 5 seconds.

Further, in some embodiments, applying the spin cycle may include rotating the partially-fabricated device300iat a first rate for a first time period. And in such embodiments, the first rate may be 900 to 1000 rpm. And in such embodiments, the first time period may be 38 to 118 seconds. With this arrangement, a first portion of the thickness of the protective layer348may be formed. The spin cycle may further include accelerating the partially-fabricated device300iat a second rate for a second time period before rotating the partially-fabricated device300iat the first rate for the first time period. In some embodiments, the second rate may be 450 to 500 rpm per second. Moreover, in some embodiments, the second time period may be 2 seconds.

Further still, in some embodiments, applying deceleration cycle comprises decelerating the partially-fabricated device300iat a rate for a time period. And in such embodiments, the rate may be 450 to 500 rpm per second. And in such embodiments, the time period may be 2 seconds.

Moreover, in some embodiments, the partially-fabricated device300imay be placed in a vacuum chuck before placing the first material on the partially-fabricated device300i.

After the first step, the first material may be baked at a temperature for a time period. In some embodiments, the temperature may be 90 degrees C. Moreover, in some embodiments, the time period may be 1 minute.

In such an example, a second step may involve placing a second material on the first material, applying a spread cycle, applying a spin cycle, and applying a deceleration cycle.

In some embodiments, placing the second material on the first material may include pouring (or pipetting) the second material onto the first material.

Moreover, in some embodiments, applying the spread cycle may include rotating the partially-fabricated device300iat a first rate for a first time period. And in such embodiments, the first rate may be 500 rpm. And in such embodiments, the first time period may be 5 to 8 seconds. With this arrangement, the second material may be spread over the first material. The spread cycle may further include accelerating the partially-fabricated device300iat a second rate for a second time period before rotating the partially-fabricated device300iat the first rate for the first time period. In some embodiments, the second rate may be 100 to 250 rpm per second. Moreover, in some embodiments, the second time period may be 2 to 5 seconds.

Further, in some embodiments, applying the spin cycle may include rotating the partially-fabricated device300iat a first rate for a first time period. And in such embodiments, the first rate may be 900 to 1000 rpm. And in such embodiments, the first time period may be 38 to 118 seconds. With this arrangement, a second portion of the thickness of the protective layer348may be formed. The spin cycle may further include accelerating the partially-fabricated device300iat a second rate for a second time period before rotating the partially-fabricated device300iat the first rate for the first time period. In some embodiments, the second rate may be 450 to 500 rpm per second. Moreover, in some embodiments, the second time period may be 2 seconds.

Further still, in some embodiments, applying deceleration cycle comprises decelerating the partially-fabricated device300iat a rate for a time period. And in such embodiments, the rate may be 450 to 500 rpm per second. And in such embodiments, the time period may be 2 seconds.

And in some embodiments, the partially-fabricated device300imay be removed from the vacuum chuck after applying the deceleration cycle.

After the second step, the first and second material may be baked at a temperature for a time period. In some embodiments, the temperature may be 90 degrees C. Moreover, in some embodiments, the time period may be 10 minutes. And such an example may further involve baking the first and second materials until room temperature at a rate. In some embodiments, the rate may be 2 degrees C. per minute.

In addition, the protective layer348may be patterned in a variety of ways. For example, the first and second material may be patterned by exposing and developing. And, in such an example, the first and second material may be exposed and developed in steps.

In such an example, a first step may involve exposing the first and second material to light at an intensity for a first time period. In some embodiments, the light may be ultra violet light (UV light) that may be generated by a mercury lamp. Moreover, in some embodiments, the intensity may be the intensity may be 16 to 19 mW/cm2. Further, in some embodiments, the first time period may be 26 seconds. Moreover, in such an example, a second step may involve repeating the first step. In another example, the first time period may include one or more cycles (e.g., 4 cycles) where each of the one or more cycles includes an exposure time period (e.g., 20 seconds) and waiting time period (e.g., 30 seconds to 2 minutes).

Further, in such an example, a third step may involve developing the first and second material by soaking in a fluid for a second time period. In some embodiments, the fluid may comprise four parts DI and one part a fluid comprising potassium borates. And in such embodiments, the fluid comprising potassium borates may be AZ® 400K Developer sold by AZ Electronics Materials. Moreover, in some embodiments, the second time period may be 4 minutes. Further still, in such an example, a fourth step may involve repeating the third step.

Moreover, the partially-fabricated device300jmay be further processed after formation of the protective layer348over the sensor electrodes340. The protective layer348may be further processed in a variety of ways. For example, the protective layer348may be further processed by rinsing in a fluid and drying with a gas. In some embodiments, the fluid may include DI water. Moreover, in some embodiments, the gas may include nitrogen.

In such an example, the partially-fabricated device300jmay then baked at a temperature for a time period. In some embodiments, the temperature may be 90 degrees C. Moreover, in some embodiments, the time period may be 20 minutes.

Further, the partially-fabricated device300imay be cleaned before forming the protective layer348over the sensor electrodes340. The partially-fabricated device300imay be cleaned in a variety of ways. For example, the partially-fabricated device300imay be cleaned by soaking in a first fluid, rinsing in a second fluid, and drying with a gas. In some embodiments, the first fluid may include acetone. Moreover, in some embodiments, the second fluid may include IPA. Further, in some embodiments, the gas may include nitrogen.

Further still, the partially-fabricated device300imay be baked before forming the protective layer348over the sensor electrodes340. The partially-fabricated device300imay be baked at a temperature for a time period. In some embodiments, the temperature may be 90 degrees C. Moreover, in some embodiments, the time period may be 5 minutes. Further, in some embodiments, the partially-fabricated device300imay be baked on a hot plate. After the partially-fabricated device300iis baked, the partially-fabricated device300imay be cooled to room temperature.

Next, an electronic component350is mounted to the electrical contacts324to provide a partially-fabricated device300k, as shown inFIG. 3k. The electronic component350could include, for example, one or more integrated circuits (ICs) and/or one or more discrete electronic components. Heat, pressure, a pick-and-place tool and a bonding medium (anisotropic conductive paste (ACP), anisotropic conductive film (ACF), solder and flux, solder paste, solder followed by underfill, etc.), or a flip-chip bonder, for example, may be used to adhere a first surface352of the electronic component350to the electrical contacts324. The electronic component350has a second surface354opposite the first surface362.

As shown inFIG. 3l, a surface356of the first bio-compatible layer310is treated to provide a partially-fabricated device300l, such that a surface of another bio-compatible layer, such as a second bio-compatible layer, bonds to the surface during formation of the other bio-compatible layer. The surface356of the first bio-compatible layer310may be treated in a variety of ways. For example, the surface356of the first bio-compatible layer310may be treated by etching using an inductively coupled plasma at a power for a time period. With this arrangement, the surface356of the first bio-compatible layer310may be roughened. In some embodiments, the inductively coupled plasma may include an oxygen plasma. Moreover, in some embodiments, the power may be 400 W with a 300 W bias. Further, in some embodiments, the time period may be 1 minute. Other plasmas and/or types of plasmas may be used as well, such as a plasma asher, a reactive ion etcher, etc.

The partially-fabricated device300kmay be baked at a temperature for a time period before treating the surface356of the first bio-compatible layer310. In some embodiments, the temperature may be 90 degrees C. Moreover, in some embodiments, the time period may be 1 hour.

As shown inFIG. 3m, a second bio-compatiable layer358is formed over the first bio-compatible layer310, the electronic component350, the antenna322, the electrical interconnects338, the protective layer348, the electrical contacts324, and the electrical interconnects326to provide a partially-fabricated device300m. The second bio-compatible layer358defines a second side360of the bio-compatible device. That is, the second bio-compatible layer358defines an outer edge of the bio-compatible device.

In an example, the second bio-compatible layer358can be composed of the same polymeric material as the first bio-compatible layer310. However, in other examples, the second bio-compatible layer358can be composed of a different polymeric material than the first bio-compatible310. The second bio-compatible layer358can be any one of the polymeric materials mentioned herein that is both bio-compatible and electrically insulating. The second layer of bio-compatible material370thus serves to seal and insulate the components.

Moreover, the second bio-compatible layer358may have a variety of thicknesses. For example, the second bio-compatible layer358may have a thickness between one or more embedded components and a surface of the second bio-compatible layer358between 5 to 100 micrometers, such as 15 micrometers. Other thicknesses for the second bio-compatible layer358are possible as well.

In an example, the second bio-compatible layer358may be formed the same or similar way as the first bio-compatible layer310may be formed. However, in other examples, the second bio-compatible layer358may be formed by a different process (or processes) than the process (or processes) used to form the first bio-compatible layer310.

For example, the second bio-compatible layer358may be formed by a microfabrication process such as chemical vapor deposition. The deposition of the second bio-compatible layer358may result in a conformal coating over the assembled components. Moreover, in an example, 35 grams of a polymeric material may be used to form the second bio-compatible layer358.

The second bio-compatible layer358may be deposited to create a continuous layer that spans the entirety of the assembled components. The second bio-compatible layer358can span a region that extends beyond a footprint of the assembled components. As a result, the assembled components can be surrounded by portions of the second bio-compatible layer358that rest directly on the first bio-compatible layer310.

Additionally or alternatively, after the second bio-compatible layer358is formed over first bio-compatible layer310, the electronic component350, the antenna322, the electrical interconnects338, the protective layer348, the electrical contacts324, and the electrical interconnects326, the first bio-compatible layer310and the second bio-compatible layer358may be annealed and/or sintered. With this arrangement, the second bio-compatible layer358may bond to the first bio-compatible layer310.

Moreover, the partially-fabricated device300lmay be cleaned before forming the second bio-compatible layer358over the first bio-compatible layer310, the electronic component350, the antenna322, the electrical interconnects338, the protective layer348, the electrical contacts324, and the electrical interconnects326. The partially-fabricated device300lmay be cleaned in a variety of ways. For example, the partially-fabricated device300lmay be cleaned by rinsing in a fluid, drying with a gas, and baking at a temperature for a time period. In some embodiments, the fluid may include DI water. Moreover, in some embodiments, the gas may include nitrogen. Further, in some embodiments, the temperature may be 90 degrees C. Further still, in some embodiments, the time period may be 60 minutes.

Further, the partially-fabricated device300lmay be plasma cleaned before forming the second bio-compatible layer358over the first bio-compatible layer310, the electronic component350, the antenna322, the electrical interconnects338, the protective layer348, the electrical contacts324, and the electrical interconnects326. The partially-fabricated device300lmay be plasma cleaned in a variety of ways. For example, the partially-fabricated device300lmay be plasma cleaned at a power for a time period. In some embodiments, the power may be high. Moreover, in some embodiments, the time period may be 5 minutes.

Next, an etch mask362is formed over a portion363of the second bio-compatible layer358to provide a partially-fabricated device300n, as shown inFIG. 3n. The etch mask362may include a variety of materials. For example, the etch mask362may include one or more photoresist layers, such as one photoresist layer comprising cyclopentanone. In such an example, the etch mask362may be KMPR® sold by Micro Chem. However, in other examples, the etch mask362may include one or more metal layers and/or one or more nitride layers.

Moreover, the etch mask362may have a variety of thicknesses. For example, the etch mask362may have a thickness between 100 to 150 micrometers, such as 120 or 130 micrometers. Other thicknesses of the etch mask362are possible as well.

In an example, the etch mask362may be formed by spin coating and patterning. However, in other examples, the etch mask362may be formed by microfabrication processes such as evaporation and/or sputtering.

The etch mask362may be spin coated in a variety of ways. For example, the etch mask362may be spin coated in steps. In such an example, a first step may involve placing a first material on the partially-fabricated device300m, applying a spread cycle, applying a spin cycle, and applying a deceleration cycle.

In some embodiments, placing the first material on the partially-fabricated device300mmay include pouring (or pipetting) the first material onto the partially-fabricated device300m.

Moreover, in some embodiments, applying the spread cycle may include rotating the partially-fabricated device300mat a first rate for a first time period. And in such embodiments, the first rate may be 500 rpm. And in such embodiments, the first time period may be 5 seconds. With this arrangement, the first material may be spread over the partially-fabricated device300m. The spread cycle may further include accelerating the partially-fabricated device300mat a second rate for a second time period before rotating the partially-fabricated device300mat the first rate for the first time period. In some embodiments, the second rate may be 100 rpm per second. Moreover, in some embodiments, the second time period may be 5 seconds.

Further, in some embodiments, applying the spin cycle may include rotating the partially-fabricated device300mat a first rate for a first time period. And in such embodiments, the first rate may be 1000 rpm. And in such embodiments, the first time period may be 38 to 118 seconds. With this arrangement, a first portion of the thickness of the etch mask362may be formed. The spin cycle may further include accelerating the partially-fabricated device300mat a second rate for a second time period before rotating the partially-fabricated device300mat the first rate for the first time period. In some embodiments, the second rate may be 500 rpm per second. Moreover, in some embodiments, the second time period may be 2 seconds.

Further still, in some embodiments, applying the deceleration cycle comprises decelerating the partially-fabricated device300mat a rate for a time period. And in such embodiments, the rate may be 500 rpm per second. And in such embodiments, the time period may be 2 seconds.

Moreover, in some embodiments, the partially-fabricated device300mmay be placed in a vacuum chuck before placing the first material on the partially-fabricated device300m.

The first step may further involve baking the first material at a temperature for a time period. In some embodiments, the temperature is 90 degrees C. Moreover, in some embodiments, the time period may be 5 minutes.

In such an example, a second step may involve placing a second material on the first material, applying a spread cycle, applying a spin cycle, and applying a deceleration cycle.

In some embodiments, placing the second material on the first material may include pouring (or pipetting) the second material onto the first material.

Moreover, in some embodiments, applying the spread cycle may include rotating the partially-fabricated device300mat a first rate for a first time period. And in such embodiments, the first rate may be 500 rpm. And in such embodiments, the first time period may be 5 seconds. With this arrangement, the second material may be spread over the first material. The spread cycle may further include accelerating the partially-fabricated device300mat a second rate for a second time period before rotating the partially-fabricated device300mat the first rate for the first time period. In some embodiments, the second rate may be 100 rpm per second. Moreover, in some embodiments, the second time period may be 5 seconds.

Further, in some embodiments, applying the spin cycle may include rotating the partially-fabricated device300lat a first rate for a first time period. And in such embodiments, the first rate may be 1000 rpm. And in such embodiments, the first time period may be 38 to 118 seconds. With this arrangement, a second portion of the thickness of the etch mask362may be formed. The spin cycle may further include accelerating the partially-fabricated device300mat a second rate for a second time period before rotating the partially-fabricated device300mat the first rate for the first time period. In some embodiments, the second rate may be 500 rpm per second. Moreover, in some embodiments, the second time period may be 2 seconds.

Further still, in some embodiments, applying deceleration cycle comprises decelerating the partially-fabricated device300mat a rate for a time period. And in such embodiments, the rate may be 500 rpm per second. And in such embodiments, the time period may be 2 seconds.

And in some embodiments, the partially-fabricated device300mmay be removed from the vacuum chuck after applying the deceleration cycle.

After the first and second material is spin coated, the first and second material may be baked at a first temperature to a second temperature at a rate for a time period. In some embodiments, the first temperature is 65 degrees C. Moreover, in some embodiments, the second temperature is 90 to 95 degrees C. Further, in some embodiments, the rate is 120 degrees C. per hour. Further still, in some embodiments, the time period may be 1 hour. In another example, the first and second material may be baked at 90 degrees C. for 1 hour.

After the first and second material is baked, the first and second material may be cooled to room temperature at a rate. In some embodiments, the rate is 450 degrees C. per hour or 120 degrees C. per hour.

The etch mask may362be patterned in a variety of ways. For example, the first and second material may be patterned by exposing and developing. And, in such an example, the first and second material may be exposed and developed in steps.

In such an example, a first step may involve exposing the first and second material to light at an intensity for a first time period. In some embodiments, the light may be ultra violet light (UV light) that may be generated by a mercury lamp. Moreover, in some embodiments, the intensity may be the intensity may be 16 to 19 mW/cm2. Further, in some embodiments, the first time period may be 30 seconds. Moreover, in such an example, a second step may involve repeating the first step. In another example, the first time period may include one or more cycles (e.g., 3 cycles) where each of the one or more cycles includes an exposure time period (e.g., 20 seconds) and a waiting time period (e.g., 30 seconds to 2 minutes)

Further, in such an example, a third step may involve baking the first and second material at a temperature for a second time period. In some embodiments, the temperature may be 90 degrees C. Moreover, in some embodiments, the second time period may be 2 minutes. Further still, in such an example, a fourth step may involve developing the first and second material using a fluid comprising 1-methoxy-2-propyl acetate. In such an example, the fluid may be SU-8 Developer® sold by Micro Chem. In some embodiments, the time period may be 15 or 10 minutes.

Moreover, the partially-fabricated device300nmay be further processed after formation of the etch mask362over the portion363of the second bio-compatible layer358. The partially-fabricated device300nmay be further processed in a variety of ways. For example, the partially-fabricated device300nmay be further processed by rinsing in a fluid, blow drying with a gas, and baking at a temperature for a time period. In some embodiments, the fluid may include IPA. Moreover, in some embodiments, the gas may include nitrogen. Further, in some embodiments, the temperature may be 90 degrees C. Further still, in some embodiments, the time period may be 60 minutes.

Moreover, the partially-fabricated device300mmay be cleaned before forming the etch mask362over the portion363of the second bio-compatible layer358. The partially-fabricated device300mmay be cleaned in a variety of ways. For example, the partially-fabricated device300mmay be cleaned by soaking in a first fluid, rinsing in a second fluid, and drying with a gas. In some embodiments, the first fluid may include acetone. Moreover, in some embodiments, the second fluid may include IPA. Further, in some embodiments, the gas may include nitrogen.

Further, the partially-fabricated device300mmay be baked before forming the etch mask362over the portion363of the second bio-compatible layer358. The partially-fabricated device300mmay be baked in a variety of ways. For example, the partially-fabricated device300mmay be baked at a temperature for a time period. In some embodiments, the temperature may be 90 degrees C. Moreover, in some embodiments, the time period may be 5 minutes.

As shown inFIG. 3o, exposed portions364of the second bio-compatible layer358(i.e., the portions that are not covered by the etch mask362) are removed to provide a partially-fabricated device300o. In an example, the exposed portions364of the second bio-compatible layer358are removed by etching using an inductively coupled plasma at a power for a time period. In some embodiments, the inductively coupled plasma may include an oxygen plasma. Moreover, in some embodiments, the power may be 400 W at a 300 W bias. Further, in some embodiments, the time period may be 33 minutes. And, in such an example, the etching may comprise one or more cycles that comprises an etch period followed by a rest period, such that the partially-fabricated device300nmay cool down. In some embodiments, the etch period may be 3 minutes. Moreover, in some embodiments, the rest period may be 2 minutes. Further, in some embodiments, the one or more cycles may be 11 cycles. And, in some embodiments, the one or more cycles may be applied in sequence. Other plasmas and/or types of plasmas may be used as well, such as a plasma asher, a reactive ion etcher, etc.

In such an example, a first portion364A of the exposed portions364of the second bio-compatible layer358that is located above the protective layer348is etched to thereby form an opening370in the second bio-compatible layer358. In some embodiments, the opening370may have a dimension of between 500 to 700 micrometers. The opening370may have a variety of shapes, such as a square shape with rounded corners, a rectangular shape, a circular shape, etc.

Moreover, in such an example, a second portion364B of the exposed portions364of the second bio-compatible layer358are etched through to the sacrificial metal layer304thereby leaving excess material372. With this approach, the etch mask362may define a shape366of the bio-compatible device and/or a shape368of the antenna322.

Further, as illustrated inFIG. 3o, at least a portion of the protective layer348is removed thereby leaving a portion348B of the protective layer348. In an example, the portion of the protective layer348is removed by the inductively coupled plasma that etches the exposed portions364of the second bio-compatible layer358. In some embodiments, the portion of the protective layer348that is etched may have a thickness between 20 and 30 micrometers. And, as illustrated inFIG. 30, at least a portion of the etch mask362is removed thereby leaving a portion362B of the etch mask362. In an example, the portion of the etch mask362is removed by the inductively coupled plasma that etches the exposed portions364of the second bio-compatible layer358.

Next, the portion348B of the protective layer348is removed to thereby expose the sensor electrodes340to provide a partially-fabricated device300p, as shown inFIG. 3p. The portion348B of the protective layer348may be removed in a variety of ways. For example, the portion348B of the protective layer348may be removed by dissolving the portion348B of the protective layer348in a fluid at temperature for a time period. In some embodiments, the fluid may comprise n-methyl pyrrolidinone. And in such embodiments, the fluid may be Remover PG® sold by Micro Chem. Moreover, in some embodiments, the temperature may be 90 degrees C. Further, in some embodiments, the time period may be 5 minutes.

Moreover, in an example, removal may further involve rinsing in a fluid and drying with a gas. In some embodiments, the fluid may include IPA. Moreover, in some embodiments, the gas may include nitrogen.

As shown inFIG. 3q, the sacrificial metal layer304is removed to release the bio-compatible device300qfrom the working substrate302. The sacrificial metal layer304may be removed in a variety of ways. For example, the sacrificial metal layer304may be removed by dissolving the sacrificial metal layer304in a fluid at a temperature for a time period. In some embodiments, the fluid may comprise four parts DI and one part a fluid comprising potassium borates. And in such embodiments, the fluid comprising potassium borates may be AZ® 400K Developer sold by AZ Electronics Materials. Moreover, in some embodiments, the temperature may be room temperature. Further, in some embodiments, the time period may be 5 minutes or multiple hours, such as 6 to 10 hours.

Moreover, in an example, removal may further involve soaking in a fluid, rinsing with a fluid, and drying. In some embodiments, the fluid may include DI water. Moreover, in some embodiments, drying may involve hand drying on a towel.

As illustrated inFIG. 3q, the bio-compatible device300qincludes the first bio-compatible layer310, the antenna322, the electrical contacts324, the electrical interconnects326, the electrical interconnects338, the sensor electrodes340, the second bio-compatible layer358, the opening370, the first side312of the bio-compatible device, and the second side360of the bio-compatible device. The first bio-compatible layer310and the second bio-compatible layer358encapsulates the assembled components, except the sensor electrodes340are exposed by the opening370.

The bio-compatible device300qis suitable for incorporation into a biological environment, such as within a body-mountable device or an implantable medical device, for example. Due to the encapsulating bio-compatible material, the surrounding environment is sealed from the embedded components. For example, if the bio-compatible device300qis implanted in a biological host, or placed in an eye-mountable device to be exposed to tear fluid, the bio-compatible device300qis able to be exposed to fluids of the biological host (e.g., tear fluid, blood, etc.), because the entire exterior surface is coated with bio-compatible material, except that the sensor electrodes340are exposed to allow detection of one or more analytes in the fluid.

The description inFIGS. 3a-qdescribes one example of a process for fabricating a bio-compatible device that can be embedded in an eye-mountable device. However, the process described with reference toFIGS. 3a-qmay be employed to create bio-compatible devices for other applications, such as other mountable devices or implantable electronic medical device applications. Such implantable electronic medical devices may include an antenna for communicating information (e.g., sensor results) and/or inductively harvesting energy (e.g., radio frequency radiation). Implantable electronic medical devices may also include electrochemical sensors or they may include other electronic devices. The process described with reference toFIGS. 3a-qmay be used to create bio-compatible devices suitable to be mounted on or in another part of the body, such as the skin, a tooth, or on a tissue in the mouth, for example.

FIG. 4illustrates a device (or a partially-fabricated device)400according to an example embodiment. In particular, the device400includes a conductive pattern402that defines an antenna404, electrical interconnects405, sensor electrodes406, electrical contacts408, and electrical interconnects410; a protective layer412over the sensor electrodes406; an electronic component414mounted to the electrical contacts408; and a bio-compatible layer416over the electronic component414, the antenna404, the protective layer412, the electrical contacts408, and the electrical interconnects410. The bio-compatible layer416defines a first side418and a second side420of a bio-compatible device.

As illustrated inFIG. 4, the sensor electrodes406are covered by the protective layer412. Moreover, as illustrated inFIG. 4the antenna404, the electrical interconnects405, the protective layer412, the electrical contacts408, and the electrical interconnects410are covered by the bio-compatible layer416.

In some embodiments, the conductive pattern402may take the form or be similar in form to the conductive pattern342; the antenna404may take the form or be similar in form to the antenna322; the sensor electrodes406may take the form of or be similar in form to the sensor electrodes340, the electrical contacts408may take the form of or be similar in form to the electrical contacts324; the electrical interconnects410may take the form of or be similar in form to the electrical interconnects326; the protective layer412may take the form of or be similar in form to the protective layer348; the electronic component414may take the form of or be similar in form to the electronic component350; the bio-compatible layer416may take the form of or be similar in form to the first bio-compatible layer310and the second bio-compatible layer358; the first side418of the bio-compatible device may take the form of or be similar in form to the first side312of the bio-compatible device; and/or the second side420of the bio-compatible device may take the form of or be similar in form to the second side360of the bio-compatible device.

In some embodiments, a portion of the bio-compatible layer416is configured to be etched by an inductively coupled plasma (e.g., an oxygen plasma) to form an opening in the bio-compatible layer. Moreover, in at least one such embodiment, the protective layer412is configured to be removed through the opening in the bio-compatible layer416to thereby expose the sensor electrodes406, and at least a portion of the protective layer412is configured to be etched by the inductively coupled plasma. Further, in at least one such embodiment, the protective layer412is configured to be removed through the opening in the bio-compatible layer416to thereby expose the sensor electrodes406, and at least portion of the protective layer412is configured to be dissolved in a fluid.

FIG. 5is a flowchart of a method500for fabricating a bio-compatible device, according to an example embodiment. The method500may involve forming a first bio-compatible layer (block502). The first bio-compatible layer defines a first side of a bio-compatible device. The first bio-compatible layer may be the same as or similar to the first bio-compatible layer310. Moreover, the first bio-compatible layer may be formed the same or similar way as the first bio-compatible layer310may be formed as described with reference toFIG. 3b. For instance, in some embodiments, the first bio-compatible layer may comprise paraylene.

The method500may involve forming a conductive pattern on the first bio-compatible layer (block504). The conductive pattern defines an antenna, sensor electrodes, electrical contacts, and one or more electrical interconnects. The conductive pattern may be the same as or similar to the conductive pattern342and/or the conductive pattern402, the antenna may be the same as or similar to the antenna322and/or the antenna404, the electrical contacts may be the same as or similar to the electrical contacts324and/or the electrical contacts408, and the one or more electrical interconnects may be the same as or similar to the electrical interconnects326, the electrical interconnects338, the electrical interconnects405, and/or the electrical interconnects410.

The method500may involve forming a protective layer over the sensor electrodes, such that the sensor electrodes are covered by the protective layer (block506). The protective layer may be the same as or similar to the protective layer348and/or the protective layer412. Moreover, the protective layer may be formed the same or similar way as the protective layer348may be formed as described with reference toFIG. 3j.

The method500may involve mounting an electronic component to the electrical contacts (block508). The electronic component may be the same as or similar to the electronic component350and/or the electronic component414. Moreover, the electronic component may be mounted to the electrical contacts the same or similar way as the electronic component350may be mounted to the electrical contacts324as described with reference toFIG. 3k. For instance, in some embodiments, mounting an electronic component to the electrical contacts may comprise bonding the electronic component to the electrical contacts using anisotropic conductive paste.

The method500may involve forming a second bio-compatible layer over the first bio-compatible layer, the electronic component, the antenna, the protective layer, the electrical contacts, and the one or more electrical interconnects (block510). The second bio-compatible layer defines a second side of the bio-compatible device. The second bio-compatible layer may be the same as or similar to the second bio-compatible layer358. Moreover, the second bio-compatible layer may be formed the same or similar way to as the second bio-compatible layer may be formed as described with reference toFIG. 3m. For instance, in some embodiments, the second bio-compatible layer may comprise paralyene.

The method500may involve removing a portion of the second bio-compatible layer to form an opening in the second bio-compatible layer (block512). The opening may be the same or similar to the opening370. The portion of the second bio-compatible layer may be removed to form an opening in the second bio-compatible layer the same or similar way as a portion of the second bio-compatible layer358may be removed to form the opening370in the second bio-compatible layer358as described with reference toFIGS. 3n-o. For instance, in some embodiments, the opening may have a dimension between 500 to 700 micrometers.

Moreover, in some embodiments, removing a portion of the second bio-compatible layer to form an opening in the second bio-compatible layer comprises forming an etch mask over the second bio-compatible layer, wherein the etch mask exposes the portion of the second bio-compatible layer; and etching, using an inductively coupled plasma, the portion of the second bio-compatible layer exposed by the etch mask to thereby form the opening. Further, in some embodiments, the etch mask may define a shape of the bio-compatible device. Further still, in some embodiments, the etch mask may define a shape of the antenna. The etch mask may be same as or similar to the etch mask362, and the inductively coupled plasma may be the same as or similar to the inductively coupled plasma described with reference toFIG. 3o.

The method500may involve removing the protective layer through the opening in the second bio-compatible layer to thereby expose the sensor electrodes (block514). The protective layer may be removed through the opening in the second bio-compatible layer to thereby expose the sensor electrodes in the same or similar way as the protective layer348may be removed through the opening370in the second bio-compatible layer358to thereby expose the sensor electrodes348as described with reference toFIGS. 3o-p.

For instance, in some embodiments, removing the protective layer through the opening in the second bio-compatible layer to thereby expose the sensor electrodes comprises etching, using the inductively coupled plasma, at least a portion of the protective layer through the opening in the second bio-compatible layer. Moreover, in some embodiments, removing the protective layer through the opening in the second bio-compatible layer to thereby expose the sensor electrodes comprises dissolving at least a portion of the protective layer in a fluid. The fluid may be the same as or similar to the fluid used to dissolve the portion348B of the protective layer348described with reference toFIG. 3p.

The method500may further involve forming a sacrificial metal layer on a working substrate, wherein the first bio-compatible layer is formed on the sacrificial metal layer; and removing the sacrificial metal layer to release the bio-compatible device from the working substrate. The working substrate may be the same as or similar to the working substrate302, and the sacrificial metal layer may be the same as or similar to the sacrificial metal layer304. The sacrificial metal layer may be formed the same or similar way as the sacrificial metal layer304may be formed as described with reference toFIG. 3a. Moreover, the sacrificial metal layer may be removed to release the bio-compatible device from the working substrate the same or similar way as the sacrificial metal layer304may be removed to release the bio-compatible device300qfrom the working substrate302as described with reference toFIG. 3q.

For instance, in some embodiments, the sacrificial metal layer comprises at least one metal layer that adheres to the working substrate. Moreover, in some embodiments, the sacrificial metal layer comprises at least one metal layer that bonds to the first bio-compatible layer. Further, in some embodiments, removing the sacrificial metal layer to release the bio-compatible device from the working substrate comprises dissolving the sacrificial metal layer in a fluid. The fluid may be the same as or similar to the fluid used to dissolve the sacrificial metal layer304described with reference toFIG. 3q.

The method500may further involve treating a surface of the first bio-compatible layer, such that a surface of the second bio-compatible layer bonds to the surface of the first bio-compatible layer during formation of the second bio-compatible layer. The surface of the first bio-compatible layer may be the same as or similar to the surface356of the first bio-compatible layer310. The surface of the first bio-compatible layer may be treated the same or similar way as the surface356of the first bio-compatible layer310may be treated as described with reference toFIG. 3l.

For instance, in some embodiments, treating the surface of the first bio-compatible layer comprises treating the surface of the first bio-compatible layer with an inductively coupled plasma. The inductively coupled plasma may be the same as or similar to the inductively coupled plasma used to treat the surface356of the first bio-compatible layer310as described with reference toFIG. 3l.

FIG. 6is a flow chart illustrating a method600for forming a conductive pattern, according to an example embodiment. The method600may be performed in connection with block504of method500. The method600may involve forming a seed layer over the first bio-compatible layer (block602). The seed layer may be the same as or similar to the seed layer314. The seed layer may be formed the same or similar way as the seed layer314may be formed as described with reference toFIG. 3c.

The method600may involve forming a first sacrificial layer over a portion of the seed layer (block604). The first sacrificial layer may be the same as or similar to the first sacrificial layer316. The first sacrificial layer may be formed the same or similar way as the first sacrificial layer316may be formed as described with reference toFIG. 3d.

The method600may involve forming a first metal layer over portions of the seed layer not covered by the first sacrificial layer (block606). The first metal layer defines the antenna, the electrical contacts, and at least one electrical interconnects of the one or more electrical interconnects. The first metal layer may be the same as or similar to the first metal layer320. The first metal layer may be formed the same or similar way as the first metal layer320may be formed as described with reference toFIG. 3e.

The method600may involve removing the first sacrificial layer (block608). The first sacrificial layer may be removed in the same or similar way as the first sacrificial layer316may be removed as described with reference toFIG. 3f.

The method600may involve removing portions of the seed layer not covered by the first metal layer (block610). The portions of the seed layer not covered by the first metal layer may be removed the same or similar way as the portion318of the seed layer314is removed as described with reference toFIG. 3f.

The method600may involve forming a second sacrificial metal layer over a portion of the first bio-compatible layer and a portion of the first metal layer (block612). The second sacrificial layer may be the same as or similar to the second sacrificial layer330. The second sacrificial layer may be formed the same or similar way as the second sacrificial layer330may be formed as described with reference toFIG. 3g.

The method600may involve forming a second metal layer over portions of the first bio-compatible layer and portions of the first metal layer not covered by the second sacrificial layer (block614). The second metal layer defines the sensor electrodes and at least one electrical interconnects of the one or more electrical interconnects. The second metal layer may be the same as or similar to the second metal layer336. The second metal layer may be formed the same or similar way as the second metal layer336may be formed as described with reference toFIG. 3h.

The method600may involve removing the second sacrificial layer (block616). The second sacrificial layer may be removed the same or similar way as the second sacrificial layer330may be removed as described with reference toFIG. 3i.

The method600may further involve forming a third sacrificial layer over the first metal layer. In some embodiments, the third sacrificial layer may be formed over the first metal layer before removing portions of the seed layer not covered by the first metal layer. The third sacrificial layer may be the same or similar to the first sacrificial layer and/or the second sacrificial layer. The third sacrificial layer may be formed the same or similar way as the first sacrificial layer may be formed and/or the second sacrificial layer may be formed.

The method600may further involve removing the third sacrificial layer. In some embodiments, the third sacrificial layer may be removed after removing portions of the seed layer not covered by the first metal layer. The third sacrificial layer may be removed the same or similar was as the first sacrificial layer may be removed and/or the second sacrificial layer may be removed.

FIG. 7depicts a computer-readable medium configured according to an example embodiment. In example embodiments, the example system can include one or more processors, one or more forms of memory, one or more input devices/interfaces, one or more output devices/interfaces, and machine-readable instructions that when executed by the one or more processors cause a system to carry out the various functions, tasks, capabilities, etc., described above.

In some embodiments, the disclosed techniques can be implemented by computer program instructions encoded on a non-transitory computer-readable storage media in a machine-readable format, or on other non-transitory media or articles of manufacture.FIG. 7is a schematic illustrating a conceptual partial view of a computer program product700that includes a computer program for executing a computer process on a computing device, to perform any of the methods described herein.

In one embodiment, the computer program product700is provided using a signal bearing medium702. The signal bearing medium702may include one or more programming instructions704that, when executed by one or more processors may provide functionality or portions of the functionality described above with respect toFIGS. 1-6. In some examples, the signal bearing medium702can include a non-transitory computer-readable medium706, such as, but not limited to, a hard disk drive, a Compact Disc (CD), a Digital Video Disk (DVD), a digital tape, memory, etc. In some implementations, the signal bearing medium702can be a computer recordable medium708, such as, but not limited to, memory, read/write (R/W) CDs, R/W DVDs, etc. In some implementations, the signal bearing medium702can be a communications medium710, such as, but not limited to, a digital and/or an analog communication medium (e.g., a fiber optic cable, a waveguide, a wired communications link, a wireless communication link, etc.). Thus, for example, the signal bearing medium702can be conveyed by a wireless form of the communications medium710.

The one or more programming instructions704can be, for example, computer executable and/or logic implemented instructions. In some examples, a computing device is configured to provide various operations, functions, or actions in response to the programming instructions704conveyed to the computing device by one or more of the computer readable medium706, the computer recordable medium708, and/or the communications medium710.

The non-transitory computer readable medium706can also be distributed among multiple data storage elements, which could be remotely located from each other. The computing device that executes some or all of the stored instructions can be a microfabrication controller, or another computing platform. Alternatively, the computing device that executes some or all of the stored instructions could be remotely located computer system, such as a server.

Where example embodiments involve information related to a person or a device of a person, some embodiments may include privacy controls. Such privacy controls may include, at least, anonymization of device identifiers, transparency and user controls, including functionality that would enable users to modify or delete information relating to the user's use of a product.