The implant schematics is shown Figure 1. The bill of materials for implant is given in [Table-1](#tabImp). The reasoning of the selected components is explained in the publication. Here, the instructions to build the implant is provided.
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<summarymarkdown="span"><i>Getting started with the breakout board</i></summary>
The BLE system on chip (SoC) is selected for its high data rate. BLEv5.x stronger physical layer (PHY) compared to BLEv4.x. Its theoretical datarate can go up to 2Mbps. The used SoC is [cc2652RB][aa] from Texas Instruments (TI). It does not require an external cyrstal oscillator, which is nice to consider when there is size constraint. Nevertheless, an open source hardware [breakout board][1] was used, which provides the basic external smd components for chip to operate. In addition, the number routed input/output pins is enough for the purpose of the project. First of all, please complete the initial programming of the chip described at the **firmware instructions** section. Then, we can start modifying the hardware components. If you do not start with the **firmware programming**, recovering the hardware after following hardware modifications requires a lot of time.
<br>The BLE system on chip (SoC) is selected for its high data rate. BLEv5.x stronger physical layer (PHY) compared to BLEv4.x. Its theoretical datarate can go up to 2Mbps. The used SoC is [cc2652RB][aa] from Texas Instruments (TI). It does not require an external cyrstal oscillator, which is nice to consider when there is size constraint. Nevertheless, an open source hardware [breakout board][1] was used, which provides the basic external smd components for chip to operate. In addition, the number routed input/output pins is enough for the purpose of the project. First of all, please complete the initial programming of the chip described at the **firmware instructions** section. Then, we can start modifying the hardware components. If you do not start with the **firmware programming**, recovering the hardware after following hardware modifications requires a lot of struggle. Therefore, please **make sure** you burn the firmware image to the chip.
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<summarymarkdown="span"><i>Removing serial communication hardware</i></summary>
We can begin with the removal of the serial connection board from breakout board to save some space. This part is marked with a scissor symbol. After this point, we can program the board via [over-the-air download (OAD)][1a]. You can find the instructions for the OAD in **firmware documentation**.
<br>We can begin with the removal of the serial connection board from [breakout board][1] to save some space. This part is marked with a scissor symbol on the back of the board. This was also marked in the [Figure below][fig.2] with a dashed line (1). After removing the serial communication PCB, we can still program the board via [over-the-air download (OAD)][1a]. You can find the instructions for the OAD in **firmware documentation**.
*Please cut the board from the dashed line to remove the serial connection interface*
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<summarymarkdown="span"><i>Setting up DC-DC regulator for MRI setting</i></summary>
We need to remove the smd inductor as shown in **Figure 2** because it has a ferite core, which would be saturated in MR envrionment and may damage the hardware. This inductor is needed for the DC-DC regulator of the SoC. You can continue without replacing another inductor and use the global LDO regulator. The global LDO consumes [30% more power][1b] than the default DC-DC buck converter. Instead of replacing the inductor with a air-core equvalent value, global LDO is better for the size constraints and simplicity. Please make sure that the internal DC/DC regulator is properly configured, if global LDO is used. The instructions are shown in the **firmware** section
<br>We need to remove the smd inductor as shown in **Figure 2** because it has a ferite core, which would be saturated in MR envrionment and may damage the hardware. This inductor is needed for the DC-DC regulator of the SoC. You can continue without replacing another inductor and use the global LDO regulator. The global LDO consumes [30% more power][1b] than the default DC-DC buck converter. Instead of replacing the inductor with a air-core equvalent value, global LDO is better for the size constraints and simplicity. Please make sure that the internal DC/DC regulator is properly configured, if global LDO is used. The instructions are shown in the **firmware** section
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<summarymarkdown="span"><i>Preparing the casing </i></summary>
<br>The [implant casing][aj] needs to be modified for the external connections and for MRI compatibility. First of all, please make sure that the screws are not magnetic. Currently, the manufacturer provide screws that are not MR compatible.<br>
We need to drill two holes to the lids. The hole at front lid will be used for the extension wire and the other at the back lid will be used for the extension antenna.
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<summarymarkdown="span"><i>Installing the extension wire</i></summary>
The leads are connected through an extension cable, which expands outside of the [implant casing][aj]. For the simplicity, there is no rubber head on the [casing][aj], which is conventionally done for the implants. Instead, we drilled a small hole on the front lid of the [casing][aj]. We need to place [feed through capacitor][ai] into the drilled hole. Then, solder the extension cable to that capacitor from the outside of the front lid. The other side of the [feed through capacitor][ai] should be connected to the rest of the PCB.
<br>The leads are connected through an extension cable, which expands outside of the [implant casing][aj]. For the simplicity, there is no rubber head on the [casing][aj], which is conventionally done for the implants. Instead, we drilled a small hole on the front lid of the [casing][aj]. We need to place [feed through capacitor][ai] into the drilled hole. Then, solder the extension cable to that capacitor from the outside of the front lid. The other side of the [feed through capacitor][ai] should be connected to the rest of the PCB.
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<summarymarkdown="span"><i>Setting up external antenna for MRI setting</i></summary>
We can configure the _2.4 GHz_ antenna for MRI setting. First, we need to remove the SMA connector from the [breakout board][1]. Then, the port of the antenna output from the board should be connected to the protection filter via an coaxial wire. The other port of the protection filter can be connected to the [external antenna][8]. Currently, there is no dedicated port in the implementation. Therefore, the connector needs to be stripped and soldered to the filter.
<br>We can configure the _2.4 GHz_ antenna for MRI setting. First, we need to remove the SMA connector from the [breakout board][1]. Then, the port of the antenna output from the board should be connected to the protection filter via an coaxial wire. The other port of the protection filter can be connected to the [external antenna][8]. Currently, there is no dedicated port in the implementation. Therefore, the connector needs to be stripped and soldered to the filter.
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## Bill of Materials
### Bill of Materials
[Table-1](#tabImp): Bill of materials of the implant
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@@ -68,6 +77,9 @@ We can configure the _2.4 GHz_ antenna for MRI setting. First, we need to remove
**Please do not use the inductors with ferromagnetic core.<br>
***There is another 2 minute [option][25]. The datasheet (German) can be found [here][ba].
