A3054 Intraperitoneal Transmitter Manual

Contents

Description

[20-MAR-26] The A3054 Intraperitoneal Transmitter (IPT) is a pill-shaped implantable telemetry sensor designed for implantation within the peritoneal cavity of a mouse or rat. The A3054 Family of transmitters is the first family in our Second Generation of telemetry sensors, and is currently in development. The A3054 provides three ECoG/LFP/EEG inputs with shared reference potential, a single EMG/ECG input with its own reference potential, an accelerometer, and a thermometer. Its pill-shaped, silicone-coated body provides stainless steel suture loops so that it may be secured within the peritonal cavity. The A3054 can be programmed at the factory to tansmit any combination of measurements from its available sensors. It can be turned on and off and re-programmed while implanted using its on-board crystal radio. Its ECoG amplifiers can be configured with AC or DC inputs, and they can be configured for any of the bandwidths 20, 40, 80, and 160 Hz. For these bandwidths, the ECoG signals will be transmitted at 64, 128, 256, and 512 SPS (samples per second) respectively. The A3054's accelerometer can be configured to provide 1 SPS of scalar activity measurement, or it can be configured to provide a one, two, or three-dimensional acceleration measurement with sample rate 32 SPS or 128 SPS per axis. The A3054's temperature sensor can be enabled to provide 1 SPS of body temperature with absolute accuracy ±0.05°C.

Figure: A3054 Intraperitoneal Transmitter (IPT) Design Sketch

When you receive an A3054 Intraperitoneal Transmitter, it will arrive in a box with a built-in magnet. The A3054 hibernates when it is near a magnet. When you remove the A3054 from its box, the A3054 powers up and initializes itself. During initialization, a white indicator light flashes three times and will be visible through the encapsulation at the base of the A3054's electrode leads. After the light flashes three times, there will be a pause of one second, and the light will flash zero to ten times to communicate that remaining battery capacity is between 0% and 100%. Once the A3054 completes its initialization, it will execute its activation protocol. The activiation protocol tells the A3054 whether it should remain idle and wait for an activation command, remain idle for a certain amount of time before activating of its own accord, to activate until it receives an deactivation commmand, or to activate for a certain amount of time before deactiviating of its own accord. When active, the A3054 executes its telemetry protocol. The telemetry protocol tells the A3054 which measurements to perform and how to transmit them with telemetry messages. If you have no command transmitter yourself, we will ship A3054s with the basic activation protocol and a custom telemetry protocol. The basic activation protocol activates the A3054 after initialization and keeps it active indefinitely. You can deactivate it by placing it back in its box or by sending it a deactivation command, but by assumption: you don't have a command transmitter, so you cannot deactivate it with a command. The custom telemetry protocol performs measurements and transmit messages according to your specifications. If, however, you do have your own command transmitter, we will ship your A3054s with the pre-programming activation protocol and a demonstration telemetry protocol. The pre-programming activation protocol keeps the A3054 idle until it receives an activation command. Following receipt of an activation command, the A3054 starts executing the demonstration telemetry protocol, and will continue to do so for about ten minutes, after which the pre-programming activation protocol will deactivate the A3054, returning it to its idle state. The demonstration protocol exercises the A3054's sensors and transmits signal in such a way as to confirm the functioning of the device. With your command transmitter, you can re-configure the A3054 by uploading a new activation protocol and a new telemetry protocol using the IPT Manager program built into our LWDAQ Software. The A3054 will not forget its new protocols when they hibernate. We use IPT as an abbreviation of Intraperitoneal Transmitter.

Figure: Intraperitoneal Transmitter Four-Section Printed Circuit Board. Layout of prototype is complete.

The A3054 Intraperitoneal Transmitter is the first of our Second Generation telemetry sensors. See the Operation chapter below for a summary of the A3054 features and options. The electronic circuit design is complete and the schematic is drawn and scanned. Our A305401A four-section rigid-flex circuit board is layed out. We are waiting for a rigid-only breadboard A305402A printed circuit board to arrive so we can test the A3054 design. We expect to be working on the breadboard during April 2026. Final design will take place in May. The first prototype A3054s will be ready to ship to test sites in July 2026. See the Design page for the progress updates. We use IPT as an abbreviation of Intraperitoneal Transmitter.

Versions

[20-MAR-26] We define the following part numbers for versions of the A3054 Intraperitoneal Transmitter. The part numbers all begin with "A3054". We use IPT as an abbreviation of Intraperitoneal Transmitter.

The shelf life of the A3054 Intraperitoneal Transmitter is the time it takes to use up 10% of the battery capacity when the device is left inactive on the shelf. The operating life is how long the device can produce reliable measurements when starting with a fresh battery. We calculate the operting life using the following formula for operating current at 37°C.

Where I_a is the active current, N is the number of active biopotential channels, and R is the total sample rate for all active biopotential channels. Here we are assuming a 1 SPS temperature and activity measurement. We can configure the A3054 Intraperitoneal Transmitter for faster monitoring of acceleration, in which case we must add the current consumed by the accelerometer measurements, which is not included in the above formula. We use IPT as an abbreviation of Intraperitoneal Transmitter.

Operation

[04-MAR-26] In the paragraphs below, we describe how we expect the A3054 Intraperitoneal Transmitter to perform when it is ready to ship. We will be re-writing these paragraphs as we go through development, adding features that turn out to be easy to add, and removing features that turn out to be impractical. The paragraphs are written in the present tense, implying that the features and software exist already, but this is not the case. These paragraphse are intended to be the Operation chapter when the device is released.

All members of the A3054 devices hibernate when in contact with a magnet. When hibernating, we say the A3054 is sleeping. While sleeping, the A3054 will not respond to commands nor transmit any information. Its internal circuits are powered down. The only component on the board that is doing anything it its magnetic sensor, which is detecting the magnetic field. We store A3054s in little boxes with built-in magnets so that they hibernate on the shelf. While asleep, the A3054 consumes less than 1 μA. Even the A3054s with the smallest batteries can hibernate for months and still retain 90% of their battery capacity.

As soon as we remove an A3054 Intraperitoneal Transmitter from its box, it wakes up and executes its initialization protocol. The initialization protocol is a fixed feature of the A3054 and cannot be re-configured outside the factory. During initialization, the A3054 flashes its white indicator lamp three times. After a second, it flashes the same lamp zero to ten times to indicate remaining battery capacity. After initialization, the A3054 executes its activation protocol. The activiation protocol tells the A3054 when and for how long to execute its telemetry protocol. The activation protocol might instruct the A3054 to begin executing the telemeetry protocol immediately, and do so indefinitely. Or it might instruct the A3054 to remain idle, waiting for commands. The activation protocol we can re-configure with a command transmitter and the IPT Manager tool in the LWDAQ Software. In its idle state, the A3054 consumes 30 μA. A typical mouse-sized A3054 with a 3500-μa·d battery capacity, can remain idle for four months before it exhausts its battery. To activate, deactivate, query, or re-program an A3054, we need a command transmitter, such as an A3042-B16 Telemetry Control Box (TCB). We use IPT as an abbreviation of Intraperitoneal Transmitter.

When active, the A3054 executes its telemetry protocol. This protocol tells the A3054 which measurements to make and what signals to transmit. The telemetry protocol defines the measurements, sample rates, channel numbers, and bandwiths. Each A3054 has a factory-assigned four-digit hexadecimal code that cannot be altered once the A3054 has left our factory. When we transmit commands, we use this code to identify a particular A3054. All A3054s within range of the command transmitter will parse and examine every command, but only the A3054 with the specified ID will respond. There is, however, a wildcard ID, 0xFFFF, to which all A3054s respond. We can upload a new telemetry protocol to any A3054 at any time with our command transmitter using the IPT Manager tool of the LWDAQ Software. We use IPT as an abbreviation of Intraperitoneal Transmitter.

The A3054 provides three ECoG inputs with a shared reference potential. These are designed to record ECoG, LFP, or EEG. They can be used with depth electrodes or surface electrodes. The amplifiers run off a 1.80-V power supply and use 0.90 V as their ground potential. The ECoG shared reference potential is equal to the amplifier ground potential, and is therefore 0.90 V above the potential of the negative battery terminal. We can configure each of the ECoG amplifiers individually with DC coupling or AC coupling. When configured with DC coupling, the amplifiers respond all the way down to 0.0 Hz, so they can detect spreading depolorizations. The amplifier gain with DC coupling will be set to ×10, giving the amplifier input a ±90-mV dynamic range, which is adequate to accommodate the galvanic potentials generated by metal electrodes. When configured with AC coupling, the amplifiers will introduce a high-pass filter with corner frequency 0.3 Hz. The amplifier gain with AC coupling will be ×45, giving the amplifier a ±20-mV dynamic range.

The three ECoG amplifiers contain a low-pass filter with 320-Hz corner frequency. We can enable sampleing of each ECoG input separately. If we enable an input, the A3054 will sample the amplifier output at 1024 SPS. We can configure the A3054 to transmit 64, 128, 256, or 512 SPS for each channel. If it transmits 64 SPS, it takes the average of 16 samples and transmits this average value sixty-four times per second. If it transmits 512 SPS, it transmits the average of 2 samples. The bandwidth for the four available sample rates is 20, 40, 80, and 160 Hz. Each ECoG telemetry signal will be assigned its own telemetry channel number by configuration. The channel numbers need not be consecutive. Telemetry channel numbers lie in the range 1-254, subject to the restriction that their remainder after dividing by sixteen cannot be zero or fifteen. Thus 31 and 32 are not legal channel numbers, but 33 and 46 are. The input impedance of the three ECoG inputs is 1.0 MΩ. At any time, the A3054 can, in response to a command, measure the impedance of its ECoG electrodes in the following manner. The A3054 configures all ECoG inputs for DC coupling. It applies a −1 mV step to the ECoG shared reference potential. From the amplitude of the step we see in each ECoG input, we can deduce the resistance between the reference electrode and each ECoG electrode with a precision of roughly 0.1% of the ECoG amplifier input impedance, or 1 kΩ. The single EMG input has its own reference potential. Its bandwidth is 2-320 Hz and its input dynamic range is ±20 mV. When enabled, we sample this input at 1024 SPS and take sample averages to produce a transmitted sample rate of 64, 128, 256, 512 or 1024 SPS. During configuration, we assign a telemetry channel number to the EMG input. We use IPT as an abbreviation of Intraperitoneal Transmitter.

The accelerometer can be configured in one of four ways. It can be disabled, it can provide 1 SPS activity measurement, or it can provide continuous acceleration measurements at two sample rates. The activity measurement is an eight-bit value derived from the sum of squares of the individual x, y, and z acceleration components. We divide this sum of squares and limit it so as to produce a value 0-255. When this value is less than 4, the animal is not moving at all, not even breathing. When the value is less than 32, the animal is resting. When it is between 32 and 127, the animal is moving around. When 128 or greater, the animal is scratching vigorously, jumpring around, or convulsing. The A3054 transmits this eight-bit value as an auxiliary telemetry message. All auxiliary messages transmitted by the A3054 will be displayed by the IPT Manager. We can also configure the accelerometer to provide 32 or 128 SPS of x, y, and z acceleration, in which case we assign the x, y, and z signals their own telemetry channel numbers and the accelerations are transmitted as unsigned, sixteen-bit integers for which 32768 is the zero value. We use IPT as an abbreviation of Intraperitoneal Transmitter.

The temperature sensor can be turned on or off. If on, it provides a 1 SPS eight-bit temperature measurement with absolute accuracy ±0.05°C and resolution 0.03125°C/cnt. This measurement is zero at a temperature we transmit to the A3054 during configuration. If we transmit 37°C as the zero-point, the temperature will span the range 33.0000°C to 40.96875°C for values 0 to 255. The eight-bit value will be transmitted with an auxiliary messages. These messages will be captured, combined, and displayed by the IPT Manager. We use IPT as an abbreviation of Intraperitoneal Transmitter.

The A3054 provides no measurement of battery voltage, but it does provide an estimate of remaining battery capacity. Instead, the A3054 keeps track of how much of its capacity it has used. It periodically increments a charge consumption counter in its non-volatile memory. Even if we put the A3054 to sleep, this counter is retained. We can request a battery capacity measurement with the IPT Manager and the A3054 will deliver the measurement in an auxiliary message, which the IPT Manager will display. The response is an eight-bit value that is 0 when the battery is fresh and 100 when it should be exhausted. We use IPT as an abbreviation of Intraperitoneal Transmitter.

Design

[04-FEB-26] For details of the design, development, and production of the A3054 Intraperitoneal Transmitter, see its Design page.