A3054 Intraperitoneal Transmitter Manual

Contents

Description

Note: The A3054 is currently in development. This manual is a preview of what we hope to release for implantation testing July 2026.

[10-APR-26] The A3054 Intraperitoneal Transmitter (IPT) is an encapsulated telemetry sensor designed for implantation in the peritoneal cavity of a mouse or a rat. The A3054 provides three unipolar ECoG/LFP/EEG inputs with shared reference potential, a single bipolar EMG/ECG input, an accelerometer, and a thermometer. Its pill-shaped, silicone-coated body provides stainless steel suture loops. The A3054 can be programmed at the factory to tansmit any combination of measurements from its available sensors. It turns on and off with a magnet. It can be activated, deactivated, and reprogrammed while implanted through the use of its on-board crystal radio. Its three ECoG amplifiers can be configured collectively for AC or DC recording and individually for bandwidths 20, 40, 80, 160, or 320 Hz. 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 be turned off. We say it is asleep. It is consuming less than one microamp from its battery. This current is being used to watch for the presence of a magnetic field. When you bring a magnet near to the sleeping A3054, it wakes up and initialize itself. During initialization, a white indicator light flashes three times and is 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 remaining battery capacity 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 inactive and wait for a wireless activation command or activate until it receives an deactivation commmand. When active, the A3054 executes its telemetry protocol. The telemetry protocol tells the A3054 which measurements to perform and how to transmit them. In order to send commands to the A3054, you will need a command transmitter, such as the A3042-B Telemetry Control Box (TCB) or A3029 Command Transmitter. If you have only a telemetry receiver in your laboratory, such as an A3027 Octal Data Receiver or A3042-A Telemetry Control Box, we will ship A3054s with the basic activation protocol and a custom telemetry protocol. Your A3054 will activate when you wake it up with a magnet, and it will deactivate when you put it to sleep with a magnet. The custom telemetry protocol performs measurements and transmit messages according to your specifications.We use IPT as an abbreviation of Intraperitoneal Transmitter.

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

If you do have your own command transmitter, we can ship your A3054s with the pre-programming activation protocol and a demonstration telemetry protocol. The pre-programming activation protocol keeps the A3054 inactive until it receives an activation command. Following receipt of an activation command, the A3054 starts executing the demonstration telemetry protocol. 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 now re-configure the A3054 by uploading a new activation protocol and a new telemetry protocol. The IPT Manager program built into our LWDAQ Software provides you with the means to set up the configuration you want and transmit your configuration to your A3054s. The A3054 stores its activation protocol and telemetry protocols in its on-board non-volatile memeory, so they do not forget their programming when you put them to sleep. We use IPT as an abbreviation of Intraperitoneal Transmitter.

The A3054 Intraperitoneal Transmitter provides a mechanism for measuring the impedance of its three of its unipolar biopotential inputs. Upon receipt of an impedance measurement command, the A3054 will apply a voltage step to its ground lead. Assuming the ground lead is of low impedance, the size of the step we see on each unipolar input will be a function of its electrode impedance and the amplifier input impedance. The A3054 can measure electrode impedance with a precision of around 5 kΩ rms. The A3054 also provides an estimate of its remaining battery capacity, which it achieves by keeping track of how long it has been running, and taking into account the current consumption of its telemetry protocol. The A3054 will transmit an auxiliary message with its remaining capacity every few seconds, and these messages will be received and decoded by the IPT Manager tool, either when we are watching a live recording, or replaying an existing recording.

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. We have just completed testing of the first breadboard circuit. All technical challenges have been met. We expect to have the first encapsulated prototypes ready for implantation testing in July 2026. See the Design page for the progress updates. We use IPT as an abbreviation of Intraperitoneal Transmitter.

Versions

[10-APR-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 asleep on the shelf. The operating life is how long the device can produce reliable measurements when starting with a fresh battery. The operating life depends upon the telemetry protocol. In particular, it depends upon the total number of samples per second the telemetry protocol transmits. 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. Each active channel will have a sample rate that is a strict function of its bandwidth. The sample rates for bandwidths 20, 40, 80, 160, and 320 Hz are 64, 128, 256, 512, 1024 SPS respectively. Our formula assumes we are transmitting a 1 SPS temperature measurement and a 1 SPS inertial 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. As an example, suppose we activate only one ECoG input at 256 SPS, for which we will get 80-Hz bandwidth. The A3054 will consume 58 μA. With a pair of SR936 batteries, it will run for sixty days. Or we could program the same device to record one ECoG channel at 512 SPS for 160-Hz bandwidth and the other two ECoG channels at 64 SPS for 20-Hz bandwidth, as well as ECG at 256 SPS for 80-Hz. The current consumption will be 117 μA. It will run for thirty days. If we configure this A3054's ECoG inputs for DC coupling, we can watch for ictal activity and spreading depolarization in the animal's brain with one ECoG channel, spreading depolarization in two other locations with the two other ECoG channels, and measure both heartbeat and respiration with the ECG input. We also have inertial activity and body temperature. We use IPT as an abbreviation of Intraperitoneal Transmitter.

Operation

[10-APR-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 wake up and go to sleep with the touch of a magnetic field. When A3054 is sleeping, it 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 waiting for a magnetic field to appear. While asleep, the A3054 consumes less than 1 μA. Even the A3054s with the smallest batteries can sleep for months and still retain 90% of their battery capacity.

As soon as we wake up an A3054 Intraperitoneal Transmitter with a magnet, it 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 whether or not it should remain inactive or begin execution of a telemetry protocol. When executing a telemetry protocol we say the A3054 is active. The activation protocol we can re-configure with a command transmitter and the IPT Manager tool in the LWDAQ Software. In its inactive state, the A3054 consumes 35 μA at 37°C. A typical mouse-sized A3054 with a 3500-μa·d battery capacity can remain inactive 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 that share the same reference potential. These are called X1-X3 and their reference potential is GND. The reference potential is also the ground potential of the A3054 amplifiers. We say these three are unipolar inputs. The unipolar inputs 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 an internal 0.90-V power supply as their signal ground. We can configure the three unipolar inputs for DC coupling or AC coupling, although we must pick either AC or DC for all three at once. We cannot configure them individually. When configured with DC coupling, the amplifiers respond all the way down to 0.0 Hz, so they can record spreading depolorizations. The amplifier gain with DC coupling is ×16, giving the amplifier input a ±55-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 is ×62, giving the amplifier a ±15-mV dynamic range. The input impedance of the three unipolar inputs is 1 MΩ. The A3054's bipolar input consists of two leads X4P and X4N that we implant anywhere close together in the body to record a local biopotential independent of the three unipolar potentials. The bipolar input amplifier subtracts the X4N from X4P and amplifies the difference by ×20 to give us a differential dynamic range of ±45 mV. The differential impedance of the bipolar input is 200 kΩ.

We can enable and disable sampling of each biometric input separately, and we can set each sample rate separately. If we enable an input, the A3054 always samples the amplifier output at 1024 SPS. We can configure the A3054 to transmit 64, 128, 256, 512, or 1024 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 five available sample rates is 20, 40, 80, 160 and 320 Hz. Each active biopotential signal must be assigned its own telemetry channel number by its telemetry protocol. 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 unipolar inputs is 1.0 MΩ. At any time, the A3054 can, in response to a command, measure the impedance of its uniploar input electrodes in the following manner. It applies a −7.16-mV step to the unipolar reference potential. From the amplitude of the step we see in each unipolar input, we can deduce the resistance between the GND lead and the unipolar input lead with a precision of roughly 0.5% of the unipolar input impedance, or ±5 kΩ. The single EMG input has its own reference potential. 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 A3054's temperature sensor can be turned on or off. If on, it provides a 1 SPS eight-bit temperature measurement with absolute accuracy ±0.1°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.