ME-BIT magnetoelectric nerve stimulator, 2022
Applications
ME-BIT magnetoelectric stimulation
The March 31, 2022 paper reports MagnetoElectric-powered Bio Implants (ME-BITs) that receive power and digital commands from an external magnetic transmitter. The primary affiliations include Rice, UT Medical Branch, UTHealth, Duke, Cambridge and Baylor. The animal application separates direct contact from vascular stimulation and delivery.
This is not Stentrode recording hardware, an ultrasound-powered StimDust mote or the later 2025 distributed ME network. Sharing a wireless mechanism does not make their circuits and cohorts interchangeable.
The Rice magnetoelectric bioelectronics lab brief links this work to source-grounded faculty and laboratory context.
Hardware and variants
| Component | Published specification |
|---|---|
| ME transducer | 1.75 × 5 × 0.3 mm laminated Metglas/PZT film |
| ASIC | 1 × 0.8 mm, 180-nm CMOS |
| System | External field transmitter, ME film, ASIC, energy-storage capacitor, electrodes/lead |
| Encapsulated form | Introduction:3 × 2.15 × 14.8 mm; PLA capsule with nonconductive epoxy |
| Direct rat configuration | 6.2 mm³, 30 mg; two 1 × 1-mm gold pads spaced 2 mm apart |
| Catheter descriptions | Packageable within 11 Fr in design text; demonstrated 9 Fr sheath delivery later in paper |
The rodent volume is not substituted for the longer encapsulated endovascular package. The 9/11 Fr passages describe different packaging/delivery scopes and do not supply one universal catheter requirement.
Commands and stimulation
The transmitter uses 345 kHz resonance, 350 kHz for the lower-amplitude data state and 400 kHz for phase-change notches. The paper reports 4.6 kbps digital data and an 18-bit stimulation payload, with a stated maximum 1-kHz stimulation rate under its timing scheme.
Voltage-controlled stimulation is programmable from 0.3-3.3 V at 4-bit resolution, with monophasic/biphasic options. The ASIC paragraph lists 0.05-1.2-ms pulse widths at 3-bit resolution, while animal protocols repeatedly report 1.5-ms pulses. That pulse-width discrepancy is preserved rather than corrected by assumption.
Efficiency is not one number
The paper reports greater-than 90% stimulation efficiency for 1.5-3.3 V and ASIC consumption below 9 µW. These are circuit metrics, not transmitter-to-implant power-transfer efficiency. Ex-vivo power delivery reaches 4 cm under the tested transmitter conditions; it is not a 4-cm implanted pig stimulation result.
Figure 3 reports approximately 6 W transmitter power and 1.17 mW implant power at 30 mm, while its caption states 0.01% efficiency. The caption’s numbers and label are retained as reported rather than silently recalculated into a replacement measurement.
Safety and chronic limits
The paper’s modeled field satisfies its cited IEEE electric-field/SAR limits but lies outside the more restrictive ICNIRP exposure range. “Within safety limits” is therefore standard-dependent, not blanket compliance.
Chronic use still requires hermetic packaging, vascular-health studies and assessment of thrombosis/antithrombotic needs. Lead-containing PZT requires a suitable biocompatible barrier or an alternative material. Acute histology without observed damage does not establish months of safe intravascular implantation.
Model boundary
No full model is supplied. Specified transducer/ASIC dimensions and one package envelope do not establish every variant’s internal placement, lead tip, contact map or tissue-fixed orientation.