Gas sensing with porous nanodrums

Delft University of Technology

Gas sensing with porous nanodrums

Roslon, Irek; Dolleman, Robin Joey; Solera Licona, Hugo; Lee, Martin; Siskins, Makars; Madauss, L.; Schleberger, M.; Alijani, Farbod; Steeneken, Peter

Publication date 2019

Document Version Final published version Citation (APA)

Roslon, I., Dolleman, R. J., Solera Licona, H., Lee, M., Siskins, M., Madauss, L., Schleberger, M., Alijani, F., & Steeneken, P. (2019). Gas sensing with porous nanodrums. Poster session presented at Graphene Week 2019, Helsinki, Finland.

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Microchannel flow

5

The devices consist of two-layer graphene suspended over cavities. Lasers actuate the membrane thermally and detect its motion.

Gas-specific fingerprint

The device

1

Gas sensing

3

4

Thermal conduction

Gas sensing with

porous nanodrums

I.E. Roslon¹, R.J. Dolleman²

³, H.Licona², M.Lee², M. Siskins²,

L. Madauss⁴, M. Schleberger⁴, F. Alijani¹ and P.G. Steeneken¹

²

3 Institute of Physics, RWTH Aachen University, Germany, 4 Fakultat fur Physik, Universitat Duisburg-Essen, Germany

Real data

Imaginary data Model imaginary partModel real part

Resonance -0.4 -0.2 0 0.2 104 105 106 107 Frequency (Hz) 108 Thermal Permeation

Im(z ), Re(z ) (a.u.

) ω ω 2 μm Microdrum Milled Perforation 1 μm 285 nm SiO2 Si 50x PID BE PBS DM VNA λ/4 PD Gas Vac 0 10 20 30 40 50 60 70 80 90 100 10-3 ₁₀-2 ₁₀-1

Effective thermal conductivity gas (W/mK)

125 mbar 500 mbar 1000 mbar Thermal time τ (ns) th Kr CF4 SF6 CO2 Ar N2 Ne He

We show a platform for studying nanoscale

thermodynamics which can enable new types of

permeation based gas sensors.

CO2 N2 Ne He CF4 SF6 0.1 1 10 0.01 100 Frequency (MHz) 60 mbar Effusion

Ne

N

2 Ar CO

2

Kr

SF

6

CF

4

He

Square root of mass (u0.5)

4

8

12

0

0

400

800

1200

Permeation time

τ (

ns)

1600

2000

2

The two peaks in the response describe thermodynamic properties of the system:

Gas permeation time constant τ

Thermal equilibration time constant τ

gas

th

The frequency response of the drums shows two peaks in the imaginary part below the mechanical resonance.

The gas opens a new thermal pathway, decreasing the thermal equilibration

time constant.

The thermal equilibration time constant depends on the thermal contact of the membrane with the surrounding and the heat capacity of the membrane.

6

Conclusion

The pore size, number of perforation and cumulative area can be adjusted to shift the permeation peak and investigate the transitional flow between molecular and continuum.

Here we show infuence of a permeation resistance by a channel connecting the cavity with the pore.

The permeation time is 9 times longer

through the 5 x 0.65 x 0.285 μm channel as compared to a direct connection.

In the Knudsen regime, the permeation time depends linearly on the square root of the

particle mass.

We have observed a gas specific response in pressures varying from 60 mbar to 1 bar

and with poresizes from 10 to 400 nm.

256 x 25 nm 64 x 50 nm 4 x 200 nm

Square root of mass (u0.5) 4 8 12

0 0 1000 Permeation time τ ( ns) gas 2000 3000 4000 5000 P = 1 bar Pore 0.4 -0.2 0 0.2 Response (a.u.) 10 1 0.1 0.01 100 τ_gas 10 1 0.1 0.01 100 Frequency (MHz) -0.4 -0.2 0 0.2 Response (a.u.) τ_gas Close to pore

Long channel connecting pore

0 10

4 8 12

Square root of mass (u0.5)

20 30 ( s) 25 15 5 35 2 6 10 τ gas 14 9x