## Experimental
### Layer synthesis  
Imprinted polystyrene layers for the detection of organic solvent traces in water are synthesized by mixing 210 ul of divinylbenzene (DVB), 90 ul of styrene, 3 mg of azo-isobutyronitrile (AIBN) and 4.4 mg biphenyl (working as additional porogen) with 100 ul of the imprinting template, i.e. benzene or toluene. The resulting solution was spin-coated onto the QCM and polymerized over night at 40\({}^{\circ}\)C in a saturated solvent athmosphere. Afterwards the sensors are washed with o-xylene and dried at 150\({}^{\circ}\)C to remove the template as well as the biphenyl.  
The six sensitive materials used as array coatings in composting were prepared as follows:  
_PVA(H2O):_ for preparation10 mg of polyvinylalcohol with a molar mass of 15000 g mol-1 is dissolved in 25 ml of deionized water. 60 mg of acrylic acid is added to this mixture together with a small amount of AIBN and pre-polymerized for 2 hours at 70\({}^{\circ}\)C.  
_PS(Lim):_ A mixture of 30 ul of styrene, 70 ul of divinylbenzene (DVB), 1 mg of AIBN and 300 ul of limonene is pre-polymerized for 15 min at 45\({}^{\circ}\)C. For spin-coating the resulting solution was diluted 1+4 with limonene.  
_PS (EtAc):_ The polymer was synthesized by mixing 40 ul of styrene and 60 ul of divinylbenzene together with 1 mg of AIBN. After pre-polymerizing for 10 min at 70\({}^{\circ}\)C 200 ul of ethyl acetate were added.  
_PU(PrOH) and PU(BuOH):_ For preparing the polyurethane 1 g of DPDI was mixed with 1.97 g of bisphenol A (BPA), 0.22 g of phloroglucinol and 2 ml of tetrahydrofurane (THF). After dissolution 970 ul of the respective alcohol (1-propanol or 1-butanol) were added to 30 ul of the pre-reacted solution, for spin-coating both mixtures were diluted 1+30 with the template solvent.  
_PU(EtAc):_ Solutions of 2.5 mmol of DPDI, BPA, phloroglucinol and triethanolamine (TEA) in 2 ml of ethyl acetate were prepared, respectively. These were mixed in the following ratio: 500 ul ethyl acetate, 148 ul BPA, 90 ul ploroglucinol, 10 ul TEA and 231 ul BPA. For preparing the layers the solution was diluted 1+9 with ethyl acetate.  
For the synthesis of PAH-imprinted polyurethanes 4,4'-diisocyanato-diphenylmethane (DPDI) and polyethylenged (molar mass 200; PEG200) and the template (mixtures) were dissolved in water-free pyridine, respectively. The resulting solutions contained 100 mg/ml of the monomer and were mixed in the following ratio: 545 ul DPDI, 455 ul PEG200 and 50 ul template yielding to a total of 5% imprint molecule in the matrix. After 15 minutes of pre-polymerisation the mixture was spin-coated onto the device and the template removed by heating at 90\({}^{\circ}\)C for 45 minutes.  
Polyurethane was imprinted with microorganisms (yeasts). Bisphenol A, 4,4'-diphenylmethanadiisocyanate and phloroglucinol were pre-polymerized in tetrahydrofuran (THF) at 70\({}^{\circ}\)C for around one hour until the gel point was reached. The ratio of isocyanate:hydroxy functionalities was 1:2. The diluted pre-polymer is drop or spin coated (~1000 rpm). Polymers from divinylbenzene, (meth-)acrylic acid, 4-vinylpyridine and styrene were again prepolymerized at 70\({}^{\circ}\)C in THF using azoisbutyronitrile (AIBN) as radical starter. The polymer solutions are spin coated with up to 5000 rpm to generate flat surfaces. After stamping the polymer is cured with UV light (substrate and QCM are made of quartz)