Harrick Plasma → Applications → Electronics → MEMs →
Microcantilevers, nanomechanical resonators and acoustic-wave devices turn molecular events into measurable signals: a shift in resonant frequency, a change in surface stress, a bend of a few nanometers. At that scale the sensor surface is part of the measurement. Organic residue from fabrication, handling or a previous experiment shifts baselines and blocks the linker chemistry that captures the target. A short low-pressure plasma treatment gives every chip the same clean, reactive starting surface in minutes, and Harrick Plasma users have published many papers on cantilever and resonator sensors (below).
Cleaning and silanization of cantilevers
Silicon, silicon nitride and gold-coated cantilevers are usually functionalized with silanes or thiols. Air or oxygen plasma removes organic contamination (roughly 5 nm/min) and leaves a dense layer of surface hydroxyl groups, so aminosilanes bind uniformly along the beam and from one chip to the next. Because the plasma is isotropic, all exposed surfaces of a released structure are treated, including sidewalls and edges. Researchers have used this step to build peptide-functionalized cantilever arrays that detect Bacillus subtilis spores (Dhayal), photonic microcantilever arrays for streptavidin binding (Ness) and large arrays of silicon nanowire nanomechanical sensors (Guthy). Argon plasma offers a non-oxidizing clean, used before gold deposition on piezoelectric cantilever biosensors for label-free DNA and RNA detection (Haring).
Acoustic and piezoelectric resonators
Surface acoustic wave (SAW) devices, quartz crystal resonators and piezoelectric MEMS resonators rely on thin sensing layers that must adhere and stay uniform. Air plasma oxidized parylene C-coated SAW biosensors before silanization, reducing nonspecific protein adsorption in an immunoassay (Lange). Piezoelectric MEMS resonators were oxidized in air plasma before a fluorosilane (PFDTS) coating to make a hydrophobic surface for on-chip droplet heating, mixing and viscosity sensing (Qu). Oxygen plasma also prepared the SiO2 surface of a liquid-phase, high-Q resonant sensor for APTES-based layer-by-layer assembly (Yu).
Regenerating sensors for reuse
Microstructured SAW resonators are difficult to make reproducibly, so reusing a good device is valuable. Schöck and coworkers used a Basic Plasma Cleaner (18 W, 5 min) to strip biological residue and the parylene C cover layer after use, then recoated the devices. Regenerated resonators matched freshly prepared ones in water contact angle and resonance parameters. A handheld atmospheric plasma tested in the same study damaged the interdigital transducers; the low-pressure benchtop plasma did not (Schöck).
Plasma as a functional step
Plasma can also tune the sensing layer itself. At Osaka University, air plasma from an Expanded Plasma Cleaner oxidized and restructured the palladium film on wireless quartz-resonator hydrogen sensors, lowering the energy barrier for hydrogen uptake and raising sensitivity. The packaged MEMS sensor reached a detection limit of 10 ppm or less at room temperature (Zhou 2020, Zhou 2021, Nagakubo).
Typical starting conditions
- Gas: air or oxygen to clean and hydroxylate; argon for a non-oxidizing clean.
- Power and time: 10 to 30 W for 15 s to 5 min to activate; longer runs at high power to strip polymer layers such as parylene.
- Timing: silanize or functionalize soon after treatment, before the surface picks up contamination again.
- Geometry: reactive species are diffusion-limited inside sealed or narrow channels, so treat open surfaces before packaging where possible.
Learn more about plasma treatment for MEMS, Atomic Force Microscopy, QCM-D and APTES functionalization. Working on a cantilever or resonator sensor? Tell us your sensor material and the step you want to improve, and we will point you to published conditions and the right configuration. Request a Quote
Microcantilever and Resonator Sensor Articles
Schöck N, Mann M, Pirker A, Voigt A and Länge K. “Plasma regeneration of microparticle-structured surface acoustic wave resonators for use as biosensors”. Coatings 2026 16(3): 283. 10.3390/coatings16030283
Nagakubo A, Matsukura T and Ogi H. “Sensitivity enhancement of hydrogen-gas sensor by sub nm Au on Pd surface of a wireless quartz resonator”. Jpn. J. Appl. Phys. 2024 63: 074002. 10.35848/1347-4065/ad61a7
Avramov ID and Ivanov GR. “Layer by layer optimization of Langmuir–Blodgett films for surface acoustic wave (SAW) based sensors for volatile organic compounds (VOC) detection”. Coatings 2022 12: 669. 10.3390/coatings12050669
Guha A, Sandström N, Ostanin VP, Klenerman D and Ghosh SK. “Simpler and faster quartz crystal microbalance for macromolecule detection using fixed frequency drive”. Sens. Actuators, B 2022 358: 131442. 10.1016/j.snb.2022.131442
Roy K, Shastri V, Kumar A, Rout J, Isha I, Kalyan K, Prakash J and Pratap R. “A PMUT based photoacoustic system as a microfluidic concentration detector”. Proc. SPIE 2022 11960: 1196013. 10.1117/12.2608934
Zhou L, Kato F, Nakamura N, Oshikane Y, Nagakubo A and Ogi H. “MEMS hydrogen gas sensor with wireless quartz crystal resonator”. Sens. Actuators, B 2021 334: 129651. 10.1016/j.snb.2021.129651
Roy K, Kalyan K, Ashok A, Shastri V, Jeyaseelan AA, Mandal A and Pratap R. “A PMUT integrated microfluidic system for fluid density sensing”. J. Microelectromech. Syst. 2021 30(4): 642-649. 10.1109/JMEMS.2021.3091651
Roy K, Kalyan K, Ashok A, Shastri V and Pratap R. “A PMUT integrated microfluidic system for volumetric flow rate sensing”. 2021 21st International Conference on Solid-State Sensors, Actuators and Microsystems (Transducers) 2021: 172-175. 10.1109/TRANSDUCERS50396.2021.9495576
Zhou L, Nakamura N, Nagakubo A and Ogi H. “Enhancement of sensitivity of Pd-based hydrogen-gas sensor by plasma exposure studied by wireless quartz resonator”. Jpn. J. Appl. Phys. 2020 59: SKKB02. 10.35848/1347-4065/ab78e2
Guha A, Ahmad OS, Guerreiro A, Karim K, Sandström N, Ostanin VP, van der Wijngaart W, Piletsky S and Ghosh SK. “Direct detection of small molecules using a nano-molecular imprinted polymer receptor and a quartz crystal resonator driven at a fixed frequency and amplitude”. Biosens. Bioelectron. 2020 158: 112176. 10.1016/j.bios.2020.112176
Khobragade S, Da Silva Granja C, Sandström N, Efimov I, Ostanin VP, van der Wijngaart W, Klenerman D and Ghosh SK. “Direct detection of whole bacteria using a nonlinear acoustic resonator”. Sens. Actuators, B 2020 316: 128086. 10.1016/j.snb.2020.128086
da Silva Granja C, Glen K, Sandström N, Ostanin VP, Thomas RJ and Ghosh SK. “A quartz crystal resonator for cellular phenotyping”. Biosens. Bioelectron.: X 2020 6: 100057. 10.1016/j.biosx.2020.100057
Guha A, Sandström N, Ostanin VP, van der Wijngaart W, Klenerman D and Ghosh SK. “Simple and ultrafast resonance frequency and dissipation shift measurements using a fixed frequency drive”. Sens. Actuators, B 2019 281: 960-970. 10.1016/j.snb.2018.11.052
da Silva Granja C, Sandström N, Efimov I, Ostanin VP, van der Wijngaart W, Klenerman D and Ghosh SK. “Characterisation of particle-surface interactions via anharmonic acoustic transduction”. Sens. Actuators, B 2018 272: 175-184. 10.1016/j.snb.2018.05.016
Swarbrick S, Efimov I, Ostanin VP, Klenerman D, Stolzing A and Ghosh SK. “Anharmonic acoustic effects during DNA hybridization on an electrochemical quartz crystal resonator”. Electrochim. Acta 2018 269: 526-533. 10.1016/j.electacta.2018.03.014
Kato F, Noguchi H, Kodaka Y, Chiku N, Shibata H, Abe F and Ogi H. “Multi-channel wireless quartz crystal microbalance biosensor fabricated with poly(dimethylsiloxane)”. 2017 19th International Conference on Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS) 2017: 1664-1667. 10.1109/TRANSDUCERS.2017.7994384
Qu H, Yang Y, Chang Y, Tang Z, Pang W, Wang Y, Zhang H and Duan X. “On-chip integrated multiple microelectromechanical resonators to enable the local heating, mixing and viscosity sensing for chemical reactions in a droplet”. Sens. Actuators, B 2017 248: 280-287. 10.1016/j.snb.2017.03.173
Papadakis G, Friedt JM, Eck M, Rabus D, Jobst G and Gizeli E. “Optimized acoustic biochip integrated with microfluidics for biomarkers detection in molecular diagnostics”. Biomed. Microdevices 2017 19: 16. 10.1007/s10544-017-0159-2
Haring AP, Cesewski E and Johnson BN. “Piezoelectric cantilever biosensors for label-free, real-time detection of DNA and RNA”. Methods Mol. Biol. 2017 1572: 247-262. 10.1007/978-1-4939-6911-1_17
Yu H, Chen Y, Xu P, Xu T, Bao Y and Li X. “µ-‘Diving suit’ for liquid-phase high-Q resonant detection”. Lab Chip 2016 16(5): 902-910. 10.1039/c5lc01187f
Wang J, Segatori L and Biswal SL. “Probing the association of triblock copolymers with supported lipid membranes using microcantilevers”. Soft Matter 2014 10: 6417-6424. 10.1039/c4sm00928b
Choi J-H, Kanazawa KK and Cho N-J. “Effect of a non-Newtonian load on signature S2 for quartz crystal microbalance measurements”. J. Sens. 2014 2014: 373528. 10.1155/2014/373528
Guthy C, Belov M, Janzen A, Quitoriano NJ, Singh A, Wright VA, Finley E, Kamins TI and Evoy S. “Large-scale arrays of nanomechanical sensors for biomolecular fingerprinting”. Sens. Actuators, B 2013 187: 111-117. 10.1016/j.snb.2012.09.070
Ness SJ, Anderson RR, Hu W, Richards DC, Oxborrow J, Gustafson T, Tsai B, Kim S, Mazzeo B, Woolley A and Nordin GP. “Weak adsorption-induced surface stress for streptavidin binding to biotin tethered to silicon microcantilever arrays”. IEEE Sens. J. 2013 13(3): 959-968. 10.1109/JSEN.2012.2225613
Lange K, Gruhl FJ and Rapp M. “Surface acoustic wave (SAW) biosensors: coupling of sensing layers and measurement”. Methods Mol. Biol. 2013 949: 491-505. 10.1007/978-1-62703-134-9_31
Saitakis M and Gizeli E. “Quantification of the effect of glycocalyx condition on membrane receptor interactions using an acoustic wave sensor”. Eur. Biophys. J. 2011 40(2): 209-215. 10.1007/s00249-010-0632-9
Lock JP, Geraghty E, Kagumba LC and Mahmud KK. “Trace detection of peroxides using a microcantilever detector”. Thin Solid Films 2009 517(12): 3584-3587. 10.1016/j.tsf.2009.01.062
Bender F, Roach P, Tsortos A, Papadakis G, Newton MI, McHale G and Gizeli E. “Development of a combined surface plasmon resonance/surface acoustic wave device for the characterization of biomolecules”. Meas. Sci. Technol. 2009 20: 124011. 10.1088/0957-0233/20/12/124011
Lee HJ, Namkoong K, Cho EC, Ko C, Park JC and Lee SS. “Surface acoustic wave immunosensor for real-time detection of hepatitis B surface antibodies in whole blood samples”. Biosens. Bioelectron. 2009 24(10): 3120-3125. 10.1016/j.bios.2009.04.009
Golovko DS, Butt H-J and Bonaccurso E. “Transition in the evaporation kinetics of water microdrops on hydrophilic surfaces”. Langmuir 2009 25(1): 75-78. 10.1021/la803474x
Cular S, Branch DW, Bhethanabotla VR, Meyer GD and Craighead HG. “Removal of nonspecifically bound proteins on microarrays using surface acoustic waves”. IEEE Sens. J. 2008 8(3): 314-320. 10.1109/JSEN.2008.917478
Lange K, Grimm S and Rapp M. “Chemical modification of parylene C coatings for SAW biosensors”. Sens. Actuators, B 2007 125(2): 441-446. 10.1016/j.snb.2007.02.039
Williams RD, Upadhyayula AK and Bhethanabotla VR. “High frequency thickness shear mode devices for organic vapor sensing”. Sens. Actuators, B 2007 122(2): 635-643. 10.1016/j.snb.2006.07.016
Dhayal B, Henne WA, Doorneweerd DD, Reifenberger RG and Low PS. “Detection of Bacillus subtilis spores using peptide-functionalized cantilever arrays”. J. Am. Chem. Soc. 2006 128(11): 3716-3721. 10.1021/ja0570887
Salomäki M, Loikas K and Kankare J. “Effect of polyelectrolyte multilayers on the response of a quartz crystal microbalance”. Anal. Chem. 2003 75(21): 5895-5904. 10.1021/ac034509z
Grate JW and Kaganove SN. “Strongly hydrogen-bond acidic polymer and methods of making and using”. US Patent 6,015,869, 2000.
Crooks RM, Yang HC, McEllistrem LJ, Thomas RC and Ricco AJ. “Interactions between self-assembled monolayers and an organophosphonate: detailed study using surface acoustic wave-based mass analysis, polarization modulation FTIR spectroscopy and ellipsometry”. Faraday Discuss. 1997 107: 285-305. 10.1039/a704586g