Past, Present, and Future of
OSI's Telemetry System



Presentation to the Institute of Neurology, UCL

10-JUL-25 (Updated 11-JUL-25)



Kevan Hashemi
Open Source Instruments Inc.
www.opensourceinstruments.com

Origins, 2004

  • A meeting between Matthew Walker and Kevan Hashemi.
  • Matthew describes his need for a telemetry system.
  • Kevan submits a Technical Proposal to Matthew in September 2004.
  • Subcutaneous Transmitter (A3009) produced 2006.
  • Subcutaneous Transmitter (A3013) produced 2007.
  • Telemetry reception reliable in radio-quiet laboratory.
  • Fourteen telemetry signal channels (1-14) only.
  • Electrode leads fail in days while implanted.
  • Silicone encapsulation bursts during shipping.

Single-Antenna System, 2007

  • Data Receiver (A3018), silver box.
  • LWDAQ Driver (A2037E), black box.
  • One antenna per receiver.
  • Alice, in photo, now full-time at OSI.

Faraday Enclosures, 2009

  • Severe 902-928 MHz interference at ION.
  • Need Faraday enclosures for isolation.
  • Operation at other locations easier.
  • Fortunate to start in difficult location.

First Successful Implant, 2010

  • Subcutaneous Transmitter (A3013A-E)
  • Frequency-modulated, 902-928 MHz, bursts.
  • First implant to survive fatigue and vaccum.
  • Encapsulated in epoxy, coated with silicone.
  • Electrode leads are silicone-coated springs.
  • Antenna is silicone-encased steel cable.
  • A Novel Telemetry System for Recording EEG in Small Animals (Sep 2011) Chang et al.

First Mouse Transmitter, 2010

  • Subcutaneous Transmitter (A3019), introduced 2010
  • In collaboration with Louise Upton, Oxford University.
  • Volume 1.4 ml, mass 2.6 g, sample rate 512 SPS, passband 0.2-160 Hz, operating life 28 days.

Antenna Combiners, 2011

  • Combines four antenna singals.
  • Can record from four Faraday enclosures.
  • Passive Combiner (ZB4PD1), left.
  • Active Combiner (A3021), right.

Octal Data Receiver (A3027E), 2013

  • Eight independent receivers in one box.
  • Four programmable digital input-output signals.
  • Power and communcation provided by newer LWDAQ Driver (A2071E), black box.
  • Option to connect 16 antennas using 8 BNC T-adaptors.
  • In 2016, expand telemetry protocol to accommodate 224 channels.

Two-Channel Mouse Transmitter, 2013

  • Two-Channel Subcutaneous Transmitter (A3028), produced 2013-2023.
  • Volume 1.4 ml, mass 2.2 g, two channels, sample rate 512 SPS, passband 0.2-160 Hz, operating life 14 days.
  • Evolve from soldered battery tabs to spot-welded tabs.

Accelerated Aging, 2014

  • Catastrophic corrosion failures in October 2014 from damaged ceramic capacitors.
  • Cracks in capacitors, cavities in epoxy, and solder flux residue all promote corrosion.
  • Corrosion in 100% humidity at 37°C places a limit on operating life.
  • Immersed in water at 60°C, corrosion is ×10 faster, call this "poaching".
  • Poach 1 device per 10 shipped, wait 1 week before shipping.

First Implantable Stimulator, 2014

  • Implantable Sensor with Lamp (A3030E).
  • Development funded by ION, devices tested at ION.
  • Combined EEG sensor and optogenetic stimulator for rats, radio-controlled.
  • Provokes optogenetic response in rats with blue and with green light.
  • The EEG signal is plagued by crosstalk from the optical power leads.

Command Transmitter, 2014

  • Command Transmitter (A3029).
  • Transmits 0.5-W pulses of 910 MHz for implantable stimulators.

Fiber-Coupled LEDs, 2014

  • Deliver light to deeper brain tissue.
  • Fiber diameter 270-450 μm.
  • Length 4-12 mm.
  • Blue LED 1 mW/mA optical output.
  • Green LED 0.5 mW/mA optical output.
  • Operates with our ISTs.

Animal Cage Camera, 2018

  • Animal Cage Camera (ACC, A3034C), camera, infra-red lights, white lights.
  • Compressed video synchronous with telemetry to ±100 ms.
  • Power and communication from Power over Ethernet.

Animal Location Tracker, 2020

  • Animal Location Tracker (ALT, A3038C), developed with ION.
  • Activity monitoring, proximity monitoring, telemetry reception.
  • Power and communication from Power over Ethernet, no more LWDAQ Driver.

Implantable Inertial Sensor, 2021

  • Implantable Inertial Sensor (IIS, A3035).
  • Developed for use with swimming fish.
  • Later adapted for use in mice and rats.
  • Provides gyroscope and accelerometer.

Head-Mounting Transmitter, 2021

  • Head-Mounting Transmitter (HMT, A3040), developed with EpilepsyGTx.
  • Four biopotential inputs, mass 2.2 g when wrapped, replaceable battery.
  • Electrode Interface Fixture (EIF) cemented to head, mates with HMT.

Telemetry Control Box, 2023

  • Telemetry Control Box (TCB-A16) provides sixteen antenna inputs, top antenna, and top power.
  • The TCB-B16 adds sixteen command transmitters that share the same antennas.
  • The TCB-B16 also provides four programmable digital input-outputs.
  • Power and communication from Power over Ethernet, no more LWDAQ Driver.

Four-Channel Rat Transmitter, 2022

  • Subcutaneous Transmitter (A3047).
  • A four-channel SCT for rats.
  • Each input has its own reference potential.
  • Can monitor EEG, EMG, EKG, and EGG at once.
  • Or provide four channels of EEG.

Implantable Stimulator-Transponder, 2023

  • Implantable Stimulator-Transponder (IST, A3041) comes in mouse and rat versions.
  • Provides electrical stimulation or power for optical stimulation.
  • Programmable stimulus, for long experiments with intermittent stimuli.

Updated SCT Circuits, 2023

  • A3048 family: single-shannel, small and slim.
  • A3048S2: 1-ch, 1.0 ml, 1.9 g, 0.2-80 Hz, 41 days.
  • A3049 family: sindle and dual-channel, all sizes
  • A3049H2Z: 2-ch, 1.4 ml, 2.9 g, 0.0-80 Hz, 40 days.
  • All come in AC or DC versions.
  • New sixteen-bit ADC consumes less current.
  • Uniform sampling reduces noise.

Depth Electrodes
  • Left to right: X, W, J, and R-Electrodes. Connect with crimp, pin, pin, and pin.
  • The X and Y we hold by tube, cement, cut tube at thinned section, and cover.
  • The J we cut wire at top and remove cannula guide.
  • The R we leave in place. We use cannula for injections at recording site.

New: Slim Two-Channel Transmitters

  • Small A3049s with side-mounting batteries
  • Slim like the A3048 family.
  • Provide two channels
  • Can record EEG and EMG.
  • Intended for sleep studies in mice.
  • A3049J2S: 2-ch, 1.3 ml, 2.7 g, 0.2-80 Hz, 24 days.

Future: Blood Pressure Monitor

  • Blood Pressure Monitor (BPM, A3051).
  • Fully implantable, 128 SPS, magnetic switch.
  • Mouse version runs for 13 days.
  • Rat version runs for 68 days.
  • Now being tested at Duzce Universitesi, Turkey.
  • A collaboration with University of Manchester.

SCT Specifications

  • Input Dynamic Range (mV) = Battery Voltage (V) ÷ Amplifier Gain
  • Convert voltage into value 0..65535, units "ADC Counts", or "cnt".
  • Output for 0V Input = 1.8 V ÷ Battery Voltage (V) × 65535.
  • Example: 1.8 ÷ 3.0 × 65535 = 39321.
  • AC transmitters: 30 mV = 3 V ÷ 100.
  • DC transmitters: 120 mV = 3 V ÷ 25.
  • AC transmitters have high-pass filter, example passband 0.2-160 Hz.
  • DC transmitters no high-pass filter, example passband 0.0-160 Hz.
  • All transmitters have a low-pass filter before sampling.
  • High-end frequency of the passband is the "bandwidth".
  • Sample rate 3.2 × bandwidth, example 256 SPS for 80 Hz.
  • Mass (g), volume (ml), operating life (days)
  • Lead length (mm) and terminations (letter codes)

Event Detection

  • The Neuroplayer's Event Classifier operates upon discrete playback intervals.
  • Calculates metrics: power, intermittency, coherence, coastline, asymmetry, spikiness.
  • Transforms each interval in a point in an n-dimensional space.
  • Build library of events and example baseline intervals, compare new intervals.
  • Several groups using PyECoG, an ION software package.
  • Suggestion: Make PyECoG easy to download, install, and use.

Documentation

  • Re-designed website December 2024
  • Telemetry Manual
  • Neurorecorder Manual
  • Neuroplayer Manual
  • Videoarchiver Manual
  • Individual Circuit Manuals
  • Development Pages
  • Design Files
  • GitHub LWDAQ Repository
  • Zipfile LWDAQ Download
  • New: Surgery Protocols

New: OSI Chatbot

  • Answers questions about setup and operation.
  • Calculates operating life from mass and bandwidth.
  • Explains how the telemetry system works.

Conclusion