Professor Mona E. Zaghloul (ECE), Professor C. Korman (ECE), and Dr.  A. Davydov (NIST)

Toxic gas such as NO2 and irritant gas such as NH3 are one of the harshest aspects that trigger or exacerbate of respiration for asthma patients. Current detectors lack portability and cannot provide daily real-time detection. Our work introduces a light, inexpensive epidermal gas sensor based on ultra-large MoSe2 Nano-sheet. The material was prepared by a NIST group under the supervision of Dr. Davydov. We obtained MoSe2 Nano-sheet with gold-assist exfoliation method and characterized the electrical and optical properties of the film. The high performing gas sensor for NO2 and NH3 was fabricated to be coupled with human skin and showed great stability with up to 30% tensile strain. In particular, the device is able to detect down to 1 parts per million (ppm) with fast response. It is effective in providing timely warnings and the sensing data can be uploaded to a cloud-based terminal so that the medical institute can easily access and provide a more accurate diagnosis.

(a) The figure shows diagram a of the circuit design for sensor data processing and delivery.
(b-c) Optical image of the assembly of the device with flexible PCB under the bandage, the optical image of detailed block circuit on flexible PCB, where 1 is the voltage divider,  2 is the amplifier ,and 3 is the microcontroller.
(d) Gas response on smartphone application under flow of gas.
(e) Gas responseon smartphone application without the flow of gas.
(f) Continuous detection of pulsed gas response curve with the connection of smartphone over 10 min.