Miniaturized Fully Passive Wireless Neural Recording With Heterogeneous Integration in Thin Packages

Wireless fully passive neural recording systems are demonstrated with heterogeneous integration of sensing, mixing, and communication components in flexible polymer dielectric films. The recording neurosensor has an antenna, antiparallel diode, and a bypass capacitor to modulate an incoming carrier signal with the neuropotentials and backscatter the mixed signal to an external reader circuit. Planar antennas are realized on liquid crystal polymer (LCP) flexible substrates with low dielectric constant. The designed antenna topology is realized with a single metal layer and eliminates the dependency on substrate thickness, and leads to thinner sensors. This is a major advance compared to prior passive neural recording with rigid and thicker substrates and components. Approximately, 80% thickness reduction and 20% volume reduction are achieved with a similar performance when compared to earlier studies. Our approach thus leads to low-cost and disposable wireless neurosensors on a flexible platform with heterogeneous integration. This article thus advances innovative wireless neural recording in three aspects: 1)advanced packaging for miniaturized neural recording with passive telemetry, through which the overall size of the sensor is reduced without degrading the performance; 2) new antenna topologies for neural recording applications; and 3) detailed power link analysis to estimate the minimum signal sensitivity.