  Diabetic ketoacidosis (DKA) is a life-threatening acute complication of
diabetes in which ketone bodies accumulate in the blood. Breath acetone (a
ketone) directly correlates with blood ketones, such that breath acetone
monitoring could be used to improve safety in diabetes care. In this work, we
report the design and fabrication of a chitosan/Pt/InP nanowire array based
chemiresistive acetone sensor. By implementing chitosan as a surface
functionalization layer and a Pt Schottky contact for efficient charge transfer
processes and photovoltaic effect, self-powered, highly selective acetone
sensing has been achieved. This sensor has an ultra-wide detection range from
sub-ppb to >100,000 ppm levels at room temperature, incorporating the range
from healthy individuals (300-800 ppb) to those at high-risk of DKA (> 75 ppm).
The nanowire sensor has been further integrated into a handheld breath testing
prototype, the Ketowhistle, which can successfully detect different ranges of
acetone concentrations in simulated breath. The Ketowhistle demonstrates
immediate potential for non-invasive ketone testing and monitoring for persons
living with diabetes, in particular for DKA prevention.
