Patent ID: 12193844

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The detailed embodiments of the present invention are disclosed herein. It should be understood, however, that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, the details disclosed herein are not to be interpreted as limiting, but merely as a basis for teaching one skilled in the art how to make and/or use the invention.

With reference to the various figures, an implantable mapping, receiving, and transmitting central nervous system data management and energy system10is disclosed. The implantable mapping, receiving, and transmitting central nervous system data management and energy system10includes a functional neurological implant12, a powered data management module14mounted within a cranial implant15, and a data storage and processing unit22. The implantable mapping, receiving, and transmitting central nervous system data management and energy system10is disclosed in U.S. patent application Ser. No. 16/297,863, which is incorporated herein by reference.

Briefly, the functional neurological implant12is composed of a neurological device implanted adjacent to, or within, the human brain or spinal cord so as to abut neurologic tissue. The data storage and processing unit22is a neurological data processing mechanism capable of receiving, storing, and/or processing neurological data sensed by the functional neurological implant12. In conjunction with the reception, storage, and/or processing of the neurological data, the data storage and processing unit22provides status information regarding the functional neurological implant12, such as battery charge, data transmission rate, and alerts if there are any issues with data integrity. The powered data management module14is constructed to gather the raw signals generated by the functional neurological implant12and transmit the signals to the data storage and processing unit22in a universally useful format. The powered data management module14is constructed to allow for use with prior, current, and future functional neurological implants12and data storage and processing units22so as to universally allow for communication therebetween.

In accordance with the disclosed embodiment, the powered data management module14is integrated into a cranial implant15as disclosed in PCT Publication No. PCT/US2016/030447, entitled “LOW-PROFILE INTERCRANIAL DEVICE,” filed May 2, 2016, U.S. Patent Application Publication No. 2018/0055640, entitled “METHOD FOR MANUFACTURING A LOW-PROFILE INTERCRANIAL DEVICE AND THE LOW-PROFILE INTERCRANIAL DEVICE MANUFACTURED THEREBY,” filed Aug. 4, 2017, or U.S. Patent Application Publication No. 2019/0209328, entitled “UNIVERSAL LOW-PROFILE INTERCRANIAL ASSEMBLY,” filed Nov. 28, 2018, all of which are incorporated herein by reference.

The functional neurological implant12and the powered data management module14are connected using electrical cabling16. While electrical cabling16is preferably used in connecting the functional neurological implant12with the powered data management module14, other wired and wireless connection mechanisms may be used including, but not limited to, infrared, Bluetooth®, radio signals, and/or optical links.

The data storage and processing unit22is remote from the powered data management module14(and the functional neurological implant12). The powered data management module14is preferably wirelessly linked to the data storage and processing unit22. The powered data management module14is designed for use with a variety of data storage and processing units22. By way of example, the data storage and processing unit22includes a Bluetooth® transceiver32, a data storage mechanism34, and a neurological monitoring system36(for example, an electrocorticography monitoring system). While wireless techniques are preferably disclosed above for linking the powered data management module14with the data storage and processing unit22, physical connections, for example, wires may be used in connecting the powered data management module14with the data storage and processing unit22. Further still, the powered data management module14may be linked with the data storage and processing unit22via a mobile device and/or a variety of other external systems.

In accordance with a preferred embodiment, the functional neurological implant12includes brain mapping functionality in the form of a neurological device20. In accordance with such an embodiment, the functional neurological implant12includes sensing elements18of the neurological device20(seeFIG.1). The sensing elements18in accordance with the present invention might be transducers capable of converting an analog signal produced by the body (for example, pressure, temperature, etc.) into an analog electrical signal that can then be used in accordance with the present invention. The sensing elements18in accordance with the present invention might also be a traditional electrode that identifies and transmits an electrical signal from the brain. The sensing elements18in accordance with the present invention might also be a combination of transducers and electrodes. Regardless, analog sensing elements such as these would result in an analog signal being sent from the sensing element18to the powered data management module14.

While examples are provided above for the structure of the functional neurological implant, it is appreciated other neurological devices may be used in accordance with the present invention and various neurological devices may be used in combination. For example, the sensing elements of the neurological device could be a digital sensing element (for example, a digital electrode). As those skilled in the art will appreciate, the utilization of a digital sensing element in conjunction with the present invention provides for enhanced signal processing as the sensed brain signals are identified and: transmitted by the digital sensing element in a digital format and no analog to digital conversion of the signal is required. Examples of digital sensing elements are found in U.S. Pat. No. 9,420,953, entitled “METHOD FOR IMPLANTING FLEXIBLE AND SCALABLE SENSOR ARRAYS INTO PATIENT TISSUES,” which is incorporated herein by reference.

The powered data management module14is composed of a data management system26and a power system60. The data management system26is constructed for universally interfacing between the functional neurological implant12and the data storage and processing unit22. As such, the powered data management module14, and in particular, the data management system26, is designed to universally link to both the functional neurological implant12and the data storage and processing unit22, regardless of whether the manufacturers of either device intended them to work together.

The operational components of the powered data management module14are housed within the cranial implant15. In particular, the data management system26and the power system60of the powered data management module14are housed within the cranial implant15. The data management system26includes a multi-channel input/output40for connection with the functional neurological implant12. Although the term multi-channel input/output is used herein to describe a preferred embodiment of a bus used by the present invention, it is appreciated a variety of bus structures could be utilized by the present invention; for example, single-channel interfaces, multi-channel interfaces, two-way communication interfaces, synchronous or asynchronous timing interfaces, and power transmission interfaces may be used within the spirit of the present invention. The multi-channel input/output40is structured to allow for the receipt, whether wired or wireless, of unprocessed raw signals coming from the functional neurological implant12to the powered data management module14, and the subsequent digital conversion and amplification necessary for transmission to the data storage and processing unit22. The multi-channel input/output40is also structured to allow for the transmission of power, where required, from the powered data management module14to the functional neurological implant12.

In accordance with a preferred embodiment, the multi-channel input/output40is a CEREPLEX™ (manufactured by BlackRock Microsystems) interface designed to connect with a variety of functional implants. As such the multi-channel input/output40includes an analog input42directly connected (whether wirelessly or wired) to the functional neurological implant12, an amplifier43and a filter44acting upon the analog signals from the functional neurological implant12as transmitted via the analog input42, a multiplexer45receiving the amplified and filtered analog signals and transmitting them to an A/D converter46for conversion of the analog signals to digital signals, and a digital output48transmitting the converted signals from the multi-channel input/output40to a transmitter50, which also forms part of the data management system26. The transmitter50includes a digital input52receiving the digital signals from the multi-channel input/output40, a data storage structure54, and a Bluetooth® transceiver56sending signals to the data storage and processing unit22.

In accordance with the preferred embodiment, the data management system26operates with the following specifications: sixty-four (64) channels of data allowing for a maximum number of sensors utilized in conjunction with the functional neurological implant12; a 900 hertz sampling rate; 16-bit processing; a low-pass filter set with a cutoff frequency of 450 hertz (for example, for eliminating aliasing and/or artifacts from cable motion and environmental noises); a wireless data transmission rate of 1 MB/second (allowing for operation with current Bluetooth® version 5.0); and a storage capacity of 8 GB of data allowing for approximately 2 hours of operation between transmissions to the data storage and processing unit22.

In addition to the multi-channel input/output40and the transmitter50, the powered data management module14also includes a power system60as briefly discussed above. The power system60is composed of a power receiver62(for example, a wireless charging coil) adapted to receive power from an external power source70(whether wired or wireless (for example, a wireless charging headset)) and a battery64storing energy for use by the multi-channel input/output40, transmitter50, and the functional neurological implant12. In a disclosed embodiment, the power system60includes four 200 milliamp-hour batteries64a-dallowing for 8 hours of operation between charges. As monitoring of battery life is critical to proper operation and monitoring, battery information is regularly transmitted to the data storage and processing unit22along with the digital signal data.

Operation of the data management system26and the power system60, that is, the powered data management module14, is controlled by a microprocessor80, which also forms part of the powered data management module14. The microprocessor80is preferably integrated with the transmitter50(and respectively electrically linked to the power system60and the multi-channel input/output40), although it is appreciated the microprocessor may be formed as a separate unit and linked with the other operational components.

While a preferred embodiment is described above for the powered data management module14, it is appreciated the powered data management module may contain various combinations of technologies without hindering the desire to allow for universal connection between the functional neurological implant12and the data storage and processing unit22. For example, the powered data management module14may include systems for constant recording and “on-board” storage, a master clock that controls recording, librarying technology (i.e., creating data sets), power management systems, and wired and/or wireless transmission mechanisms.

In practice, and after receipt of the unprocessed raw signal from the functional neurological implant12, the unprocessed raw signal is subjected to analog to digital conversion and amplification to produce a digital signal that is transmitted to the transmitter50. The digital signal is then buffered in the data storage structure54and prepared for transmission by the Bluetooth® transceiver56to the data storage and processing unit22. As the raw signal coming from the functional neurological implant12has only been digitally converted and amplified, it is considered to be a universal unprocessed signal that may be used in conjunction with various data storage and processing units22.

While a battery is disclosed as a power source in a disclosed embodiment, it is contemplated the power system could rely upon other energy sources, for example, energy harvesting systems or inductive power systems. While the various embodiments disclosed above show a single functional neurological implant communicating with the powered data management module, it is appreciated that a plurality of functional neurological implants may communicate with a single powered data management module. Such communication may be achieved either wired or wirelessly.

Referring toFIGS.5to22, a two-part molding process is used in the manufacture of the custom cranial implant15with an integrated powered data management module14as discussed above with reference toFIGS.1to4. The cranial implant15, which is composed of a cavity implant15aand a cap implant15b, is shown inFIGS.5,6,7, and8. While the two-part molding process described below is used in conjunction with the integrated powered data management module described above, it is appreciated the two-part molding process described herein may be extended for use with other neurological devices and various neurological devices may be used in combination. For example, the two-part molding process may be implemented in conjunction with ICP (intracranial pressure) devices, neurostimulation devices, therapeutic ultrasound, RF devices, etc. In addition, it is appreciated some of these devices as currently marketed are contained in housings. The traditional housings may not be necessary when the functional components are incorporated into a cranial implant as described herein, thereby saving space and permitting imaging, among other advantages.

The custom cranial implant15with the integrated powered data management module14is an implantable medical device that encapsulates various electrical components for the purposes of mapping, recording, and transmitting neural activity data. The custom cranial implant15not only properly fits within the patient's skull but also encapsulates all of the electrical components of the powered data management module14. Due to the thickness of the components of the powered data management module14(that is, the multi-channel input/output40, transmitter50, and power system60composed of a power receiver62and batteries64a-d), it is appreciated that portions of the custom cranial implant15may need to be bulked laterally beyond the contours of the native cranium. Additionally, the perimeter of the custom cranial implant15should match the height of the cranium in order to provide a smooth transition from the cranial implant15to the existing cranium.

Temporal bulking can simplify the shape of a cranial implant15by reducing the curvature and making the cranial implant15flatter in the temporal region. However, not all surgeons desire temporal bulking in a cranial implant. If the cranial implant15is designed without temporal bulking, the cranial implant15can take on a much more complicated shape, particularly as the cranial implant15contours to the sphenoid bone and zygomatic arch.

As to the design of the custom cranial implant15with the integrated powered data management module14, a disclosed embodiment uses MATERIALIZE 3-MATIC™, a data optimization software for computer design in additive manufacturing. As will be appreciated based upon the following disclosure, the cranial implant15includes a cavity implant15aand a cap implant15b. In accordance with a disclosed embodiment, an initial curve is drawn on the outer surface of a three-dimensional rendering of the skull in the approximate region where the cavity implant15awith the integrated powered data management module14is to be positioned (hemi-craniectomy). The purpose of this curve is to develop tools to help orient and position the components of the powered data management module14. This curve is not used to determine the outline of the cavity implant15awith the powered data management module14. Planes are positioned in regular intervals along the curve from anterior to posterior. References are added to each plane to assist with the construction of a surface. The references include the skull and the curve. Within each plane, a line is drawn along the outer surface of the skull. Using the planes as references, a surface is created that follows the contours of the outer surface of the native skull. The surface is then uniformly offset by 5 mm to create a second surface 5 mm below the original surface. This surface serves as a reference when positioning the components of the powered data management module14.

STL files of each component of the powered data management module14are imported into MATERIALIZE 3-MATIC™. The components are strategically positioned to follow the contours of the second surface, and hence the skull. The components are also positioned to not cut across the surface. By doing so, the components are precisely positioned 5 mm below the outer surface for use in a 5.5 mm thick implant. Because a minimally sized cavity implant15ais desired, the distance between the components is reduced as much as possible.

A new curve is then drawn on the skull which is used to create a surface large enough to encompass the components but also minimize the footprint of the cranial implant15to the extent possible. The surface is created using the original planes in conjunction with the new curve. The surface is then uniformly offset as a solid by 5.5 mm. A 3 mm chamfer is implemented on the perimeter of the cranial implant. Fifteen (15) STL files known as ‘component cutters’ are imported into MATERIALIZE 3-MATIC™. The component cutters are objects that have the same inner surface shape as the components of the powered data management module14. However, the top surfaces of the component cutters are much taller than the components of the powered data management module14and flare out at angles. The component cutters are also slightly enlarged compared to the components of the powered data management module14. The component cutters are used to Boolean subtract cavities17a-gfor the components in the 5.5 mm thick implant. The resulting implant is known as the cavity implant15a, seen inFIGS.5and6.

The components of the powered data management module14are then wrapped by 1 mm. This serves as a reference to help create a top surface that is to be at least 1 mm above the top surface of the components of the powered data management module14. The wrapped components of the powered data management module14are added as references to the plane. In each plane, sketches are drawn from the curve intersection, along the top surface of the wrapped components of the powered data management module14, and then back to the other curve intersection. Using the planes as references, a top surface is then generated. The surface is then offset to create a solid. The solid offset and the 5.5 mm thick implant, without the cavities, are merged to create a solid implant, seen inFIG.7. This implant is known as the cap implant15bbecause the top surface, which is created, acts as a cap that is used to encapsulate the components of the powered data management module14. The cap implant15brepresents the final shape and size of the custom cranial implant15with the powered data management module14, seen inFIGS.8A and8B. The position of the final prototype within the skull is shown inFIG.9.

Using a 3D printer, masters of the cavity implant15aand the cap implant15bare printed, shown inFIGS.10A and10B, and respectively labeled115aand115b. A master of the electrode plug90is not printed since a previously manufactured electrode plug is used. The master of the cavity implant115ais used to create a two-part buffstone mold82composed of a first mold84, a second mold86, and a third mold88. The first mold84is formed around the outer surface of the master of the cavity implant115a. The second mold86is molded around the sides and inner surface of the master of the cavity implant115a, seen inFIGS.11A and11B. Since the cavity implant15aand the cap implant15bhave the same inner surface and sizes, the second mold86is used to cast the third mold88, which is molded around the outer surface of the master of the cap implant115b.

In accordance with an embodiment, the first mold84and the second mold86are prepared in a cleanroom. The following steps pertain to both the first mold84and the second mold86. In practice, the following steps are performed for the first mold84and then are repeated again for the second mold86. The molds are ensured to be clean by wiping the molds using a lint-free paper towel. The mold is further ensured to be dry and free of debris before proceeding. A thin layer of petroleum jelly is wiped over the surface of the mold and any excess petroleum jelly is removed with a lint-free paper towel. Strips of tin foil are cut to an appropriate length, wherein the tin foil should be long enough to cover the length of the mold. It is appreciated two layers of tin foil may need to be overlapped to cover the width of the mold. Thereafter, a strip of tin foil is placed on the mold, the foil is pressed onto the mold (starting from the center and working towards the edges), the foil is smoothed and burnished onto the mold to remove any large wrinkles, bubbles, or any other imperfections, any excess petroleum jelly that is squeezed from under the foil is wiped away, additional layers of tin foil are placed on the mold so that the entire buffstone surface has been covered, and the tin foil mold is wiped to remove any grease or petroleum jelly residue (using a lint-free paper towel).

In accordance with another embodiment, rather than using tin foil to line the mold, MASEL SUPER-SEP™ separating medium may be used to prepare the first mold for casting. Since the first mold represents the top surface of the master of the cavity implant, trying to foil such a complex surface with hard angles can be difficult and can lead to rough implant surfaces. Therefore, a separating medium is used to test its efficacy for creating a smooth barrier between the buffstone and the uncured PMMA (poly (methyl methacrylate)). Two coats of the separating medium are applied to the first mold with 20 minutes between each coat application. The coats are allowed to dry overnight. The mold is packed with uncured PMMA and placed within a heated water bath and allowed to cure at 90° C. for 300 minutes. This is the first curing cycle. It is appreciated that while PMMA is used in accordance with a disclosed embodiment, other synthetic resins may be used where they exhibit similar beneficial material properties.

Once the first and second molds84,86are prepared, a biocompatible casting material, for example, PMMA in accordance with a disclosed embodiment, is mixed for casting the cavity implant15a. As with the mold processing step presented above, all steps are performed in a cleanroom. The amount of polymer and monomer needed for casting is determined, wherein the weight of the polymer and monomer needed is dependent on the weight of the 3D printed master of the cavity implant115a. Thereafter, the appropriate amount of polymer is weighed into a clean bowl, the appropriate amount of monomer is weighed into a clean beaker, the contents of the beaker are poured into the bowl with the polymer, and a lid is placed over the bowl and the bowl is kept under the hood. Every 5 minutes, the consistency of the PMMA mixture is checked until the desired consistency is achieved, wherein it is appreciated the mix time should not exceed 30 minutes and the contents of the bowl can be stirred periodically to ensure even mixing.

The cavity implant15ais then cast. As with the mold processing step presented above, all steps are performed in a cleanroom. Further, and before handling the PMMA, clean gloves must be worn. The PMMA is removed from the bowl. The PMMA is then kneaded, pulled, and folded for 15-30 seconds under a fume hood. The PMMA is removed from under the fume hood and placed within the implant impression within the first mold84. The PMMA is spread to mostly fill the impression. It is appreciated the PMMA should not be placed outside the perimeter of the impression. The second mold86is then placed directly over the first mold84and secured to the first mold84using bolts. The second mold86and the first mold84should be parallel to each other as the bolts are tightened to ensure the molds are closing properly. The first mold84and the second mold86are placed in the hydraulic bench press and pressure is slowly increased until the gauge stabilizes at 5 metric tons. As the pressure is gradually applied, the bolts are continually tightened so they are snug. Once 5 metric tons of pressure is applied, a torque wrench is used to tighten the bolts in a cross pattern to 20 lb-ft. Thereafter, the molds are removed from the press.

The cavity implant15ais then cured in a cleanroom. A water bath is filled with hot water, at 40±5° C. The first mold84and the second mold86are placed in the water bath and a thermocouple data logger is placed into the water bath to record temperature data. A programmed water bath cycle is run. When the cycle is complete, the water bath is drained, and the flask is removed from the water bath. The thermocouple data logger is removed, and the temperature graphs are printed and saved. Finally, it is confirmed that the water bath performed the correct curing cycle.

Following the first curing cycle, the PMMA cavity implant15ais removed and only the outer surface is lightly sanded, as seen inFIG.12. The sides and inner surface of the cavity implant15aare not sanded. The electrode plug hole92for the electrode plug90is sanded to the proper shape by applying sandpaper to a 3D printed plug master89and rotating the plug master89within the electrode plug hole92of the cavity implant15a. This allows the electrode plug hole92within the cavity implant15ato properly seal with the electrode plug90when fully assembled. The cavities17a-gof the cavity implant15aonly require light sanding for the components of the powered data management module14to fit properly.

In a molding/production room, the cavity implant15ais removed from the first mold84and the second mold86. Before removing the cavity implant15afrom the first and second molds84,86, the first and second molds84,86should be cool enough to handle without causing burns. The bolts securing the second mold86to the first mold84are removed and the second mold86is lifted from the first mold84. The PMMA cavity implant15ais then removed from the first mold84. If the cavity implant15ais stuck to the first mold84, the first mold84may be run under water to help release the cavity implant15afrom the first mold84. In the event the foil is still stuck to the cavity implant15a, as much foil as possible is removed from the cavity implant15aby hand.

The cavity implant15ais then sanded. In one embodiment, and if necessary, the flashing is removed from the cavity implant15aby breaking as much of the flashing off by hand and sanding the remaining flashing away using a rotary sander. The top surface of the cavity implant15ais sanded using a coarse sandpaper, such as 320 grit, to remove any large scratches, bumps, or other imperfections, and the thickness of the top surface of the cavity implant15ais measured. The cavities17a-gof the cavity implant15aare then sanded using coarse sandpaper, such as 320 grit, to remove any imperfections which would prevent the components of the powered data management module14from properly residing within the cavities17a-g. The shape and positioning of the cavities17a-gare checked by placing replica components of the powered data management module11within the cavities17a-gand the shape of the cavities17a-gis modified to ensure the components of the powered data management module14properly reside within the cavities17a-g. The electrode plug hole92is then sanded and shaped by placing sandpaper around the electrode plug90, placing the electrode plug90in the electrode plug hole92within the cavity implant15a, rotating the electrode plug90to allow the sandpaper to shape the electrode plug hole92in the cavity implant15a, and periodically checking the sandpaper and replacing if it is becoming worn. Throughout the sanding process, the fit of a PMMA electrode plug90with the electrode plug hole92in the cavity implant15ais periodically checked.

In one embodiment, the fit is checked by placing the electrode plug90in the cavity implant15a, applying pressure to the electrode plug90using a hand and flipping the cavity implant15aso the inner surface is facing upwards. With the cavity implant15ain the concave position, water is placed over the electrode plug90and observed for water leaks between the implant/plug interface. If a leak is observed, sanding the cavity implant15ais continued, if necessary, and if no leaks are observed, sanding the cavity implant15ais stopped. Care should be taken to not over-sand the electrode plug hole92in the cavity implant15a.

The inner surface of the cavity implant15ais then sanded and polished. Using progressively finer sandpaper, the inner surface of the cavity implant15ais sanded until it is smooth. Wet sanding should be used for higher grit sandpapers. Once all major scratches are removed, the inner surface of the cavity implant15ais polished using a polishing compound and a polishing wheel. One should then check to see if all scratches and imperfections have been removed before proceeding and make certain that the perimeter of the cavity implant15ais not altered along the edge thereof. One should also check the cavity implant15ato confirm it does not contain any major defects or debris within the cavity implant15a.

The cavity implant15ais then cleaned with dish soap. After sanding is complete, dish soap and a nylon brush are used to scrub the cavity implant15ato remove all debris and the cavity implant15ais rinsed with warm water and dried with a lint-free cloth.

The cavity implant15ais then moved to the cleanroom and cleaned with LIQUINOX®, a cleaning liquid detergent. In particular, using a 1% LIQUINOX® solution, the implant is scrubbed with a nylon brush until it is free of debris, thoroughly rinsed using deionized water, and the implant is placed on a drying rack to air dry.

Referring toFIGS.15to19, the secondary curing cycle is now disclosed. As is discussed below in detail, to make room for the electrode leads95during the secondary curing cycle, a hole97is drilled through the second mold86where the electrode leads95are to exit the cavity implant15a, seen inFIG.15. The second mold86and the third mold88are then foiled. The PMMA cavity implant15ais placed on the second mold86. The components of the powered data management module14are placed within the respective cavities17a-gand the electrode grid96is passed through the bottom of the cavity implant15a, down the hole97in the second mold86, and out to the exterior of the second mold86, as seen inFIG.16. Uncured PMMA is carefully placed on the surface of the cavity implant15aand components of the powered data management module14, with caution taken to avoid shifting the PMMA layer. The third mold88is then lowered onto the second mold86. The second and third molds86,88are closed and placed into the water bath to cure. The electrode grid96is secured to the outside of the second and third molds86,88to prevent it from becoming tangled in the washer bath's immersion circulator. The electrode grids are submerged during the entirety of the curing cycle.

In particular, the second mold86is modified in the molding/production room to accommodate the electrode grid housing98in the following manner. The master of the cavity implant115ais placed on the second mold86and the location of the electrode plug hole92is marked on the second mold86. Using a long and relatively small diameter drill bit, a pilot hole is drilled through the second mold86. The pilot hole is angled so that it originates within the marking created for the electrode plug90and exits through the opening in the bottom plate. Once a pilot hole has been drilled at the correct trajectory, a larger drill bit, that is, a drill bit having a diameter larger than the thickness of the electrode grid housing98, is used to drill the larger hole97in the second mold86at the same trajectory as the pilot hole. It is appreciated that several holes may need to be drilled to accommodate the size of the electrode grid housing98. Thereafter, and using a standard drill bit, the hole97is shaped so it is smooth, with an oval shape that is large enough to accommodate the electrode grid housing98. After the hole97has been drilled, both the second mold86and the third mold88are thoroughly cleaned using dish soap and a nylon brush to remove any debris.

The second mold86and the third mold88are then prepared in the cleanroom for casting the final implant. The following steps pertain to both the second mold86and the third mold88, and one performs the following steps for the second mold86and then repeats them for the third mold88. The mold is ensured to be clean by wiping the mold using a lint-free paper towel. The mold is then ensured to be dry and free of debris before proceeding. A thin layer of petroleum jelly is wiped over the surface of the mold and any excess petroleum jelly is removed with a lint-free paper towel. Strips of tin foil are cut to an appropriate length, wherein the tin foil is long enough to cover the length of the mold and two layers of tin foil may need to be overlapped to cover the width of the mold. Thereafter, a strip of tin foil is placed on the mold, the foil is pressed onto the mold (starting from the center and working towards the edges), the foil is smoothed and burnished onto the mold to remove any large wrinkles, bubbles, or any other imperfections, any excess petroleum jelly that is squeezed from under the foil is wiped away, additional layers of tin foil are placed on the mold so that the entire surface of the mold has been covered, and the tin foil mold is wiped to remove any grease or petroleum jelly residue (using a lint-free paper towel). For the second mold86, an ‘X’ shape is cut into the foil above the hole in the mold and the foil is pressed down into the walls of the hole, and the cleaned cavity implant15ais placed on the second mold86.

The components of the powered data management module14are then prepared for casting in the cleanroom. The components of powered data management module14are carefully and fully removed from their packaging and checked to ensure that all the components of the powered data management module14are safe from electrostatic discharges. The electrode grid housing98and the bolts used to hold it together are obtained. The electrode grid housing98is properly cleaned before proceeding.

After checking and cleaning, the electrode grid96is placed within the electrode grid housing98. The electrode grid housing98is designed to hold a 64-channel subdural electrode grid96when it is folded onto itself. Two columns of the electrode grid96are placed into the electrode grid housing98, with the exposed electrode leads95facing upwards, while avoiding bending and flexing the electrode grid96as much as possible when inserting it into the electrode grid housing98. The electrode grid96is folded along the region where no wires reside and another two columns of the electrode grid96are placed into the electrode grid housing98. If done correctly, the exposed electrode pads should be facing each other within the electrode grid housing98. The electrode grid96is folded twice more to fit the remaining portion of the electrode grid96within the electrode grid housing98. As each portion of the electrode grid96is folded into the electrode grid housing98, the leads from that portion of the electrode grid96are pressed into the neck of the electrode grid housing98to ensure it is properly seated. Once the electrode grid96is within the electrode grid housing98, the electrode grid96of the electrode grid housing98is placed over the electrode grid96, the lid is pressed down, and it is ensured that it is properly seated on the electrode grid housing98and the electrode grid96is not being pinched. Small bolts are placed through the holes in the lid and electrode grid housing98and gradually tightened in a cross pattern. The components of the powered data management module14are placed within the cavity implant15a.

The electrode grid housing98is fed through the cavity implant15aand through the hole in the second mold86. Once the electrode grid housing98is through the second mold86, the components of the powered data management module14are lowered into their respective cavities within the cavity implant15a. It is then ensured that the electrode plug90is properly seated within the cavity implant15a.

The PMMA for casting the cap implant15bis then mixed. All steps are performed in a cleanroom. The amount of polymer and monomer needed for casting is determined, wherein the weight of the polymer and monomer needed is dependent on the weight of the 3D printed cavity master. Thereafter, the appropriate amount of polymer is weighed (under the fume hood) into a clean bowl, the appropriate amount of monomer is weighed into a clean beaker, the contents of the beaker are poured into the bowl with the polymer, and a lid is placed over the bowl and the bowl is kept under the hood. Every 5 minutes, the consistency of the PMMA mixture is checked until the desired consistency is achieved, wherein it is appreciated the mix time should not exceed 30 minutes and the contents of the bowl can be stirred periodically to ensure even mixing.

The cap implant15bis then cast. As with the mold processing step presented above, all steps are performed in a cleanroom. The PMMA is removed from the bowl. The PMMA is then kneaded, pulled, and folded for 15-30 seconds under the fume hood. The PMMA is removed from under the hood and placed within the cavity implant15aand the PMMA is spread to mostly cover the cavity implant15asurface. The PMMA should not be shifted after it has been placed over the components of the powered data management module14. The third mold88is then directly secured to the second mold86using the appropriate length bolts. The second mold86and the third mold88are parallel to each other as the bolts are tightened to ensure the molds can close properly. The second mold86and the third mold88are placed in the hydraulic bench press. When placing the molds in the press, the electrode grid housing98and leads are fed through the bottom plate on the press. Using the handle to crank the press, pressure is slowly increased until the gauge stabilizes at 5 metric tons. As the pressure is gradually applied, the bolts are continually tightened so they are snug. Once 5 metric tons of pressure is applied, a torque wrench is used to tighten the bolts in a cross pattern to 20 lb-ft. Thereafter, the second and third molds86,88are removed from the press.

The cap implant15bis then cured in a cleanroom. A water bath is filled with hot water, at 40±5° C. The second and third molds86,88are placed in the water bath. The second and third molds86,88are oriented such that the leads are exiting from the top of the second and third molds86,88and the electrode grid housing98is placed on the top of the second and third molds86,88. A thermocouple data logger is placed into the water bath to record temperature data. A programmed water bath cycle is run. When the cycle is complete, the water bath is drained, and the flask is removed from the water bath. The data logger is removed, and the temperature graphs are printed and saved. Finally, it is confirmed that the water bath performed the correct curing cycle.

The cap implant15bis then removed from the second mold86and the third mold88. Before removing the cap implant15bfrom the second and third molds86,88, the second and third molds86,88should be cool enough to handle without causing burns. The bolts securing the second mold86to the third mold88are removed and the second mold86is lifted from the third mold88. The second mold86is lifted up and around the electrode grid housing98. The PMMA cap implant15bis then removed from the second mold86.

The electrode plugs90used in accordance with the present invention optimize the passage of electrode leads95from the powered data management module14through the cranial implant15and to the electrode grid96. The electrode plug90includes a plug housing99having an upper surface99a, a lower surface99b, and side walls99cextending between the upper surface99aand the lower surface99balong the perimeter of the plug housing99. The plug housing99is constructed with a circular profile, although the plug housing99could be constructed with other profiles if dictated by specific applications or needs.

The side wall99cof the plug housing99exhibits a taper as it extends from the upper surface99ato the lower surface99b. As such, the upper surface99ahas a larger diameter than the lower surface99b. The electrode plug hole92includes a similar shape, that is, the electrode plug hole92includes a larger diameter along the upper surface than the lower surface. By providing the plug housing99and the electrode plug hole92with tapered mating surfaces, a predictable fit is achieved where the electrode plug90ultimately seats at a desired position within the electrode plug hole92.

As mentioned above, the electrode plug90provides for the passage of the electrode leads95from the powered data management module14through the cranial implant15and to the electrode grid96. This is achieved by forming a plurality of holes100in the electrode plug90, wherein the holes100are shaped and dimensioned (for example, 1.5 mm diameter holes) to allow for the passage of the electrode leads95from the upper surface to the lower surface. Optimal passage of the electrode leads95through the electrode plug90is achieved by obliquely orienting the holes100relative to the planar surface defined by the upper and lower surfaces99a,99bof the electrode plug90(for example, at a 40 degree angle), as seen inFIGS.13A,13B, and13C. By obliquely orienting the holes100, sharp angles are minimized as the electrode leads95pass through the electrode plug90.

In accordance with a disclosed embodiment, four electrode leads95for the subdural electrode grid96are passed through the holes100in the electrode plug90. The tail collars from the electrode leads95are then cut and the bare inner wires are exposed. The wires from the electrode leads95, as well as the wires for the powered data management module14, are soldered in a predetermined manner, as seen inFIG.14. The length of the wire exiting the implant is to be approximately 15 mm long.

Following the secondary curing cycle, the cranial implant15is removed and the functionality of the LEDs is tested to confirm they survived the curing cycle. The electrode grid96is placed with a plastic bag and sealed with tape to prevent it from becoming damaged during sanding and polishing, as seen inFIG.17. The entire implant, both outer and inner surface, is then sanded and polished, as seen inFIG.18. The functionality of the LEDs is tested again to ensure the electronics did not sustain damage during the manufacturing process, as seen inFIG.19. The cranial implant15is placed within its respective host bone to ensure the implant fits properly following the manufacturing process, as seen inFIG.20. Thickness measurements are recorded throughout the production process, as seen inFIGS.21and22. For example, Figurer21shows measurement were taken comparing the thickness of the printed cavity master and the PMMA cavity implant after light sanding (top). Text identifies the thickness of the printed master and the thickness of the PMMA cavity implant. The measurements were taken comparing the thickness of the printed cap master and the PMMA cap implant.FIG.22shows measurements of the final footprint. The length of the leads exiting from the implant is approximately 15 mm long.

Designing the cavity implant15ato be as thick as possible is advantageous for numerous reasons. The thicker implant allows the cavities to be deeper within the cavity implant15a, which provides more support to the components of the powered data management module14which resides in the cavities. By providing more support, the deeper cavities reduce the possibility of component migration during the secondary curing cycle. Additionally, because the components of the powered data management module14can sit deeper within the cavity implant15a, less of the component is exposed above the top surface of the cavity implant15a. This means the cap implant15bof the cranial implant15can maintain a lower profile while still successfully encapsulating the components of the powered data management module14. Reducing the overall profile of the cranial implant15is not only beneficial for the patient's aesthetic appearance, but it also reduces the tension on the scalp when the surgical incision is closed during implantation. Furthermore, because the cap implant15bof the cranial implant15can maintain a lower profile due to the deeper cavities, the transition between the cap implant15band the surface of the cavity implant15acan be smoother since the components of the powered data management module14are not as prominent above the surface of the cavity implant15a. This will improve the smooth and fluid appearance of the surface of the implant.

For this 5.5 mm thick cavity implant15a, the cavities were designed to be 5 mm deep. While the depth of material between the bottom surface of the components of the powered data management module14and the inner surface of the cranial implant15is designed to be only 0.5 mm, that thickness will increase in the PMMA cranial implant15due to expansion. Therefore, the thickness of the cavities is intentionally designed to be thinner to account for expansion observed within the PMMA cranial implant15. The desired PMMA cavity thickness is 1 mm.

After the cavity implant15ais demolded, only the top surface of the cavity implant15ais sanded using 320 grit sandpaper. The sides and inner surface are not sanded in order to preserve its shape so it can properly fit with the second mold86during the secondary curing cycle. By having the cavity implant15afit with the second mold86, PMMA is less likely to migrate down the side and underneath the cranial implant15during the secondary curing cycle. Conversely, by not sanding and polishing the inner surface before the secondary curing cycle, it must be done following the secondary curing cycle after the electrode leads have been implanted. Sanding and polishing the inner surface could cause potential damage to the leads if care is not taken to protect them.

The integrity of the electrical connection was maintained throughout the secondary curing cycle. All LEDs were successfully illuminated which means the curing process did not pose a risk to the integrity of the electrical connections.

While the preferred embodiments have been shown and described, it will be understood that there is no intent to limit the invention by such disclosure, but rather, is intended to cover all modifications and alternate constructions falling within the spirit and scope of the invention.