We present a calibration method for quantitative surface-enhanced
Raman scattering (SERS) on a single-chip based on inkjet dispense
(ID-SERS). We exploit the ability of inkjet to precisely pattern microdroplets
at high resolution to encode multiple standard curves on the surface
of a single 1 mm2 SERS substrate. We demonstrate quantitative
SERS measurements with a relative standard error (RSE) below 3% for
aqueous solutions of 1,2-bis(4-pyridyl)ethylene (BPE), the lowest
reported to date. Most importantly, the RSE scales with patterning
density and sensor size, showing the potential for even higher measurement
accuracy. This calibration technique can be generalized to other plasmonic
substrates and offers several additional advantages including speed
(subsecond drop-and-dry), low sample volumes (<1 nL), and automation.
Finally, we investigate factors impacting the limit of detection of
this approach and demonstrate a 30-fold enhancement of sensitivity
via layered inkjet dispense. We believe that ID-SERS paves the way
for the development of reproducible plasmonic sensing for real-world
quantitative applications.