Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Sub-mm$^3$ Ultrasonic Free-floating Implant for Multi-mote Neural
  Recording   A 0.8 mm$^3$ wireless, ultrasonically powered, free-floating neural recording
implant is presented. The device is comprised only of a 0.25 mm$^2$ recording
IC and a single piezoceramic resonator that is used for both power harvesting
and data transmission. Uplink data transmission is performed by analog
amplitude modulation of the ultrasound echo. Using a 1.78 MHz main carrier, >35
kbps/mote equivalent uplink data rate is achieved. A technique to linearize the
echo amplitude modulation is introduced, resulting in <1.2\% static
nonlinearity of the received signal over a $\pm$10 mV input range. The IC
dissipates 37.7 $\mu$W, while the neural recording front-end consumes 4 $\mu$W
and achieves a noise floor of 5.3 $\mu$V$_{rms}$ in a 5 kHz bandwidth. This
work improves sub-mm recording mote depth by >2.5x, resulting in the highest
measured depth/volume ratio by $\sim$3x. Orthogonal subcarrier modulation
enables simultaneous operation of multiple implants, using a single-element
ultrasound external transducer. Dual-mote simultaneous power up and data
transmission is demonstrated at a rate of 7 kS/s at the depth of 50 mm.

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The categories of this paper are: astro-ph
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The categories of this paper are: patt-sol
15
The categories of this paper are: nucl-ex
21
The categories of this paper are: adap-org
17
The categories of this paper are: q-fin
3
The categories of this paper are: physics
14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph
0
The categories of this paper are: hep-ph
34
The categories of this paper are: chem-ph
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The categories of this paper are: hep-th
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The categories of this paper are: hep-ex
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The categories of this paper are: funct-an
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The categories of this paper are: cmp-lg
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The categories of this paper are: alg-geom
37
The categories of this paper are: supr-con