title: Ultrasonic beamforming system for interrogating multiple implantable sensors.
abstract: In this paper, we present an ultrasonic beamforming system capable of interrogating individual implantable sensors via backscatter in a distributed, ultrasound-based recording platform known as Neural Dust [1]. A custom ASIC drives a 7 × 2 PZT transducer array with 3 cycles of 32V square wave with a specific programmable time delay to focus the beam at the 800mm neural dust mote placed 50mm away. The measured acoustic-to-electrical conversion efficiency of the receive mote in water is 0.12% and the overall system delivers 26.3% of the power from the 1.8V power supply to the transducer drive output, consumes 0.75μJ in each transmit phase, and has a 0.5% change in the backscatter per volt applied to the input of the backscatter circuit. Further miniaturization of both the transmit array and the receive mote can pave the way for a wearable, chronic sensing and neuromodulation system.
authors.lastname: Dongjin Seo
authors.lastname: Hao-Yen Tang
authors.forename: Jose M
authors.initials: JM
authors.lastname: Carmena
authors.forename: Jan M
authors.initials: JM
authors.lastname: Rabaey
authors.forename: Elad
authors.initials: E
authors.lastname: Alon
authors.forename: Bernhard E
authors.initials: BE
authors.lastname: Boser
authors.forename: Michel M
authors.initials: MM
authors.lastname: Maharbiz
mesh_terms: D004867:Equipment Design; D008904:Miniaturization; D019736:Prostheses and Implants; D014159:Transducers; D014463:Ultrasonography