Implantable Intertial Sensor

[24-OCT-24] The Implantable Inertial Sensor (IIS) is a wireless accelerometer and gyroscope encapsulated in epoxy and silicone. It may be implanted subcutaneously in a rodent or attached extracutaneously to a fish. The IIS is equipped with a single 30-mm loop antenna that works well when immersed in water or implanted in an animal body. The IIS uses the same telemetry system as our Subcutaneous Transmitters (SCTs). We turn the IIS on and off with a magnet. We record its telemetry signals with the Neurorecorder and read them off disk with the Neuroplayer.

Figure: The Implantable Inertial Sensor (A3035B1). Mass 1.8 g, operating life 150 hrs. Provides 128 SPS from three-axis accelerometer.

The IIS is designed for designed for long-term experiments that require intermittent, short-term monitoring of angular velocity and linear acceleration. We can implant the A3035A1, for example, in a mouse and record six inertial signals for one hour every day for forty days. Or we can attach the same device to a fish, record for two hours, remove, and do the same thing twenty times with twenty different fish. The A3035A1 transmits six signals on six separate SCT telemetry channels. The signals are gyroscope x, y, z, range ±5.6 rev/s at 128 SPS (samples per second) and accelerometer x, y, z, range ±160 m/s/s at 128 SPS. Thje A3035B1, however, disables the gyroscope and transmits only x, y, and z acceleration at 128 SPS. Its operating life is 150 hrs.

Figure: Pendulum Oscillation Recorded with A3035. Recording length 225 s, as displayed in Overiview of the Neuroplayer.

Note that the IIS is not intended to serve as activity monitor. For activity monitoring, we use our Animal Location Tracker (ALT), which provides activity monitoring by measuring telemetry signal power on its array of antennas. The ALT provides activity in units of centimeters per second. Furthemore, the ALT provides the motion detection we need to discriminate between animals in video recordings, it tells us which animals socialize together, and it allows us to record which animals are asleep and awake. These measurements are provided by the ALT at no cost to the battery in the implant. Because our recording system provides activity monitoring and motion tracking, there is no need for us to build an implant for the same purpose. The IIS is designed to study the mechanics of animal movement, not animal behavior.

Development of the IIS was funded by the NSF (grant IOS 1652582) and carried out in collaboration with the Tytell Laboratory of Tufts University.

Implantable Inertial Sensor (A3035): Magnetically activated motion sensor for fish.

Technical Proposal for Implantable Inertial Sensor: Introduction to the device and presentation of original conceptual design.

Parts and Prices: A list of devices and their prices.