Point-of-care testing (POCT) has attracted great interest
because
of its prominent advantages of rapidness, precision, portability,
and real-time monitoring, thus becoming a powerful biomedical device
in early clinical diagnosis and convenient medical treatments. However,
its complicated manufacturing process and high expense severely impede
mass production and broad applications. Herein, an innovative but
inexpensive integrated sandwich-paper three-dimensional (3D) cell
sensing device is fabricated to in situ wirelessly
detect H2O2 released from living cells. The
paper-based electrochemical sensing device was constructed by a sealed
sandwiched bottom plastic film/fiber paper/top hole-centered plastic
film that was printed with patterned electrodes. A new (Fe, Mn)3(PO4)2/N-doped carbon nanorod was developed
and immobilized on the sensing carbon electrode while cell culture
solution filled the exposed fiber paper, allowing living cells to
grow on the fiber paper surrounding the electrode. Due to the significantly
shortening diffusion distance to access the sensing sites by such
a unique device and a rationally tuned ratio of Fe2+/Mn2+, the device exhibits a fast response time (0.2 s), a low
detection limit (0.4 μM), and a wide detection range (2–3200
μM). This work offers great promise for a low-cost and highly
sensitive POCT device for practical clinic diagnosis and broad POCT
biomedical applications