A Capacitive Sensor, Exploiting a YSZ Functional Layer, for Ammonia Detection

In different fields, the need for low-cost sensors allowing an early detection of (bio)quantities is emerging. This article deals with the design, realization, and characterization of a low-cost sensor for ammonia detection realized by fast prototyping techniques. The sensor is part of a more complex system aimed to assess the level of phenylalanine levels in biological fluids (blood, saliva, or urine), which would allow the development of a new approach for the self-monitoring of patients with the phenylketonuria (PKU) metabolic disorder. The obtained experimental results encourage the further development of the proposed approach. In particular, the sensor behavior has been investigated for an ammonia concentration in the range [0–2000]
$\mu \text{M}$
. The developed sensor prototype shows a responsivity of
$3.53\times 10^{-14}$
F/
$\mu \text{M}$
, a resolution of 0.15
$\mu \text{M}$
, and a span-to-resolution of
$1.3\times 10^{4}$
.