Hydra activation with MagNI

The 2020 paper tests MagNI using Hydra vulgaris as excitable tissue. A transgenic strain expresses calcium-sensitive GCaMP6s in the ectoderm. The implant supplies electrical stimulation; the reporter protein and microscope provide the measured activity readout.

Experimental configuration

A micromanipulator positions stereotrodes connected to the ME-powered device, 10 mm from the transmitter. These are external stimulation contacts sized for the animal, not a chronic test using only the implant’s on-board electrodes.

Five-second biphasic trains with 500-µs pulses at 100 Hz produced greater-than-200% GCaMP6s fluorescence increases and associated muscle contractions. The imaging setup used a 20× objective, Andor Zyla camera and 25 frames per second. This optical sampling rate is not wireless neural-data throughput.

The accessible biological section does not state an animal enrollment or repeated-trial denominator. No cohort count is inferred from one plotted fluorescence trace.

What this does not show

The paper lists spinal cord stimulation and neuropathic pain relief as application targets. It does not demonstrate those therapies in a rat, pig or human. Hydra activation, saline power recovery and seven-day soak performance are different tests.

This is not the later two-Hydra shared-transmitter experiment with the PUF-addressed platform, which uses GCaMP7b and a different stimulation protocol. No chronic tissue implantation, autonomous sensing, human therapy or pain outcome is established by this application.

Primary source

• Published primary manuscript, Section IV-C, Figures 27-28 and the separate bench/saline sections.