DE102018203848A1 - Ligand, SAMFET, method of making same and sensor - Google Patents

Abstract

The invention relates to a ligand (V) for a SAMFET (10). The ligand (V) has the structure R-S-K-S-A. Where R is a receptor group for an analyte, Sund S are independently selected from the group consisting of alkylene groups, perfluorinated alkylene groups, and aliphatic ether groups, K is an aromatic or heteroaromatic group, and A is an anchor group for a dielectric (12). The SAMFET (10) is made by providing a transistor substrate (30). This has a gate electrode (11), a dielectric (12) arranged on the gate electrode (11), a source electrode (13) arranged on the dielectric (12) and a drain electrode (14) arranged on the dielectric (12). At least the dielectric (12) is wetted with a solution of the ligand (V). Then, heat treatment of the transistor substrate (30) is performed. The SAMFET (10) thus obtained has a self-assembled monomolecular organic layer (15) with receptor groups (R) for the analyte, arranged between the source electrode (13) and the drain electrode (14) on the dielectric (12). The SAMFET may be used as part of a sensor for detecting the analyte.

Description

The present invention relates to a ligand for a SAMFET. Furthermore, the present invention relates to a SAMFET and a method for manufacturing the SAMFET. Finally, the present invention relates to a sensor comprising the SAMFET.

State of the art

Gas sensors provide an electrical voltage signal that varies depending on the presence of the analyte. For example, a gas sensor may be based on a transistor. In the transistor, current flows from a source electrode to a drain electrode as soon as an electrical voltage is applied to its gate electrode. When the active layer of a semiconductor between the source electrode and the drain electrode interacts with an analyte, the characteristics of the transistor are changed. From the US 2011/0239735 A1 For example, it is known to apply between the source electrode and the drain electrode a monomolecular organic layer of a quinquethiophene derivative which is bound to the surface of the dielectric of the gate electrode. This monomolecular organic layer is coated with another layer of a metalloporphyrin complex which can attach nitric oxide to its metal center. This sensor structure is called SAMFET (Self-Assembled Monolayer Field Effect Transistor). The function of a SAMFET is also described in detail in Organic Electronics 11 (2010), 895-898. While the monomolecular organic layer can be prepared simply by immersing the transistor substrate in a solution, applying the receptor layer to the monomolecular organic layer requires vapor deposition in a vacuum chamber, which is tedious and expensive.

Disclosure of the invention

The ligand for a SAMFET has the following structure: $${\text{RS}}^1{\text{-KS}}^2-\text{A}$$

In this case, R denotes a receptor group for an analyte, which can be detected by means of a sensor in which the SAMFET is installed. The receptor group can be selected depending on the analyte to be detected. Suitable receptor groups for constituents of gases are in particular selected from the group consisting of amine groups (NH ₂ ), hydroxy groups (OH), carboxy groups (COOH), thiol groups (SH), C ₂ to C ₁₀ alkenyl groups and aromatic C ₆ to C ₁₈ groups , Among the C ₂ to C ₁₀ alkenyl groups, a vinyl group is particularly preferred.

S ¹ and S ² are flexible spacers which allow molecules of the ligand to self-assemble in a monomolecular layer. They are independently selected from the group consisting of alkylene groups, perfluorinated alkylene groups and aliphatic ether groups. These groups may be branched or unbranched, with unbranched groups being preferred. The alkylene groups are preferably C ₂ to C ₂₀ alkylene groups and the perfluorinated alkylene groups are preferably perfluorinated C ₂ to C ₂₀ alkylene groups. By ether groups are meant groups having one or more oxygen atoms. Preference is given to aliphatic C ₂ to C ₂₀ ether groups.

K is an aromatic or heteroaromatic group. This forms a semiconducting core of the ligand which can be "doped" by the uptake or release of electrons during operation of the SAMFET. This core is preferably selected from groups based on perylenebisimide, naphthalenebisimide, pentacene, thiophene and oligothiophenes and their derivatives according to the following structural formulas:

In this case, X in each case denotes hydrogen, a cyano group (CN) or a C ₁ to C ₁₀ alkyl group. In different units, or in different aromatic or heteroaromatic rings, X may each be identical or different, n may assume values of 0 to 4, p may assume values of 0 to 2 and q may assume values of 0 to 3.

Finally, A denotes an anchor group with which the ligand can be anchored on the surface of a dielectric of the SAMFET. Preferably, this is selected from the group consisting of P (O) Y ¹ Y ² , -C (O) Y ¹ , -SH, and -SiY ¹ Y ² Y ³ . The radicals Y ¹ , Y ² and Y ^{3 are} independently selected from the group consisting of -OH, -CI, -Br, and -OZ, wherein Z is a C ₁ to C ₁₀ alkyl group.

This ligand combines the properties of a traditional SAMFET ligand and a SAMFET receptor. Thus, using this ligand, it is no longer necessary to first apply a monomolecular organic layer of the ligand on the dielectric of a transistor substrate and then subsequently coat this layer with a separate receptor layer. Rather, to complete the SAMFET, it is sufficient to apply the monomolecular organic layer of the present ligand. The task of the now no longer necessary receptor layer is taken over by the receptor groups, which can interact with the analyte. Since the receptor groups are covalently attached to the ligand, the analyte, depending on the selected combination of analyte and receptor group, even exert a more pronounced effect on the characteristics of the SAMFET, as could be achieved by means of a vapor-deposited receptor layer. This allows the manufacture of a SAMFET with a particularly high sensitivity to the analyte.

The SAMFET has a gate electrode, a dielectric disposed on the gate electrode, a source electrode disposed on the dielectric, and a drain electrode disposed on the dielectric. Between the source electrode and the drain electrode is a channel in which a monomolecular organic layer having receptor groups for an analyte is arranged. This organic layer has, in particular, the ligands described above. By connecting an analyte to the receptor groups, the characteristics of the SAMFET are changed.

The method of manufacturing the SAMFET begins by providing a transistor substrate. This has a gate electrode, a dielectric disposed on the gate electrode, a source electrode arranged on the dielectric and a drain electrode arranged on the dielectric. At least the dielectric is wetted with a solution of a ligand, the receptor groups for an analyte having. However, it is preferred that the entire transistor substrate be immersed in the solution, allowing for a particularly fast and easy fabrication of the SAMFET. By heat treating the transistor substrate, the solvent of the solution is evaporated and a monomolecular organic layer of the ligand is formed between the source electrode and the gate electrode on the dielectric.

The ligands are preferably the ligands described above. The anchor groups of the ligands are anchor groups for the dielectric of the transistor substrate.

The sensor for detecting an analyte comprises at least one SAMFET as described above. The organic layer of the SAMFET has receptor groups for the analyte to be detected by the sensor. As further components, the sensor may in particular comprise a signal processor which is electrically connected to the SAMFET and an output unit which receives signals from the signal processor.

list of figures

• 1 zeigt ein Reaktionsschema der Darstellung eines Liganden gemäß einem Ausführungsbeispiel der Erfindung.
• 2 zeigt schematisch Bereiche, in welcher ein Ligand gemäß einem Ausführungsbeispiel der Erfindung unterteilt werden kann.
• 3 zeigt eine schematische Querschnittsansicht eines SAMFETs gemäß dem Stand der Technik.
• 4 zeigt eine schematische Querschnittsansicht eines Transistorsubstrats, das zur Herstellung eines erfindungsgemäßen SAMFETs verwendet werden kann.
• 5 zeigt ein Ablaufdiagramm eines Verfahrens zur Herstellung eines SAMFETs gemäß einem Ausführungsbeispiel der Erfindung, wobei die einzelnen Verfahrensschritte bildlich illustriert sind.
• 6 zeigt eine schematische Darstellung eines SAMFETs gemäß einem Ausführungsbeispiel der Erfindung.
• 7 zeigt ein Reaktionsschema der Anbindung eines Analyten an Rezeptorgruppen der organischen Schicht eines SAMFETs gemäß einem Ausführungsbeispiel der Erfindung. Ausführungsbeispiele der Erfindung

Embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description.

• 1 Figure 9 is a reaction diagram illustrating a ligand according to an embodiment of the invention.
• 2 schematically shows areas in which a ligand can be divided according to an embodiment of the invention.
• 3 shows a schematic cross-sectional view of a SAMFET according to the prior art.
• 4 shows a schematic cross-sectional view of a transistor substrate which can be used to produce a SAMFET according to the invention.
• 5 shows a flowchart of a method for producing a SAMFET according to an embodiment of the invention, wherein the individual process steps are illustrated graphically.
• 6 shows a schematic representation of a SAMFET according to an embodiment of the invention.
• 7 shows a reaction scheme of the attachment of an analyte to receptor groups of the organic layer of a SAMFET according to an embodiment of the invention. Embodiments of the invention

The representation of a ligand according to an embodiment of the invention is shown in FIG 1 shown. For this purpose, initially 1 g (2.54 mmol) of the starting compound I are provided, whose synthesis in A. Ringk, N-Type Self-Assembled Monolayer Field-Effect Transistors and Complementary Inverters, Advanced Functional Materials, Volume 23, Issue 16, 25, 2013, pages 2016-2023 is described. This starting compound I is reacted with an excess of 1.344 g (15.24 mmol) of 1,4-diaminobutane under argon atmosphere in imidazole for 3 hours at a temperature of 160 ° C. Compound II is obtained as a sparingly soluble product.

The unfunctionalized imide group of compound II is deprotonated by means of potassium carbonate and further reacted in situ. For this purpose, 1 g (2.15 mmol) of the compound II in dimethylformamide (DMF) for 5 days at a temperature of 80 ° C with 1 g of potassium carbonate and 0.8 g (2.15 mmol) of 1-dimethylphosphoryl-12-bromododecane reacted. Here, the compound III is obtained as an intermediate, which further reacts to the compound IV. Compound IV is worked up by flash chromatography with a mixture of chloroform and acetic acid. The synthesis of 1-dimethylphosphoryl-12-bromododecane is carried out according to a procedure described in Organic Electronics 14 (2013), 1297-1304 is described.

2 ml (15.16 mmol) of trimethylbromosilane are added dropwise to 1 g (1.32 mmol) of a solution of compound IV in dichloromethane at a temperature of 0 ° C. over a period of 2 hours, and the dimethyl ligand according to the invention is then dimethylated under dimethylation Behavior. After addition of the trimethylbromosilane, the temperature of the solution is raised to 20 ° C. over a period of 48 hours. A 1: 1 mixture of methanol and water is added and the precipitate formed is filtered off. This is dissolved in trifluoroacetic acid and reprecipitated in dioxane to isolate the ligand V.

In the ligand V, the amino group acts as a receptor R, which can react, for example, with carbon dioxide from the ambient air. The buthylene group, which separates the amino group from the perylene bisimide, acts as the first flexible spacer S ¹ . The perylenebisimide group forms a semiconducting core K. This is separated by the dodecylene group as the second flexible spacer S ² from the phosphonic acid residue, which acts as anchor group A. This is in 2 shown.

In a conventional SAMFET, as seen from the US 2011/0239735 A1 and from Organic Electronics 11 (2010), 895-898 is known, has the in 3 shown construction. The SAMFET 10 has a gate electrode 11 and one on the gate electrode 11 applied layer of a dielectric 12 , On the dielectric 12 are a source electrode 13 , and a drain electrode 14 applied. In the channel between the source electrode 13 and the drain electrode 14 there is a monomolecular organic layer 15 , This consists of a self-organized layer 151 of ligands and a vapor deposited receptor layer 152 , A gaseous analyte 20 can bind to the receptor layer.

For producing a SAMFET according to an embodiment of the invention, first a transistor substrate 30 provided as it is in 4 is shown. This also has a gate electrode 11 on, which consists in the present example of doped silicon. On this is in the present case amorphous alumina as a dielectric 12 applied. A source electrode 13 and a drain electrode 14 , which in this case each consist of gold, are on the dielectric 12 applied.

In an embodiment of the method for producing a SAMFET according to the invention 10 first, the transistor substrate 30 in a first step S01 provided. As in 5 it is shown in a second step S02 with ethanol 41 cleaned and then in a third step S03 in a solution 42 of a ligand V immersed in toluene. In a fourth step S04 becomes the transistor substrate 30 out of the solution 42 taken and on a hot plate 43 , heat-treated at a temperature of 110 ° C in vacuum. It forms between the source electrode 13 and the drain electrode 14 a monomolecular organic layer of the ligand V in which the phosphoric acid radical of anchor group A is covalently bonded to the dielectric to form Al-OP oxygen bridges 12 connects. Finally, with a measuring device 44 in a final step S05 the functionality of the SAMFET has been tested.

6 schematically shows how electrons in the operation of the SAMFETs 10 from the source electrode 13 through the semiconducting cores K the ligands V to the drain electrode 14 be transported. This changes the electrical properties of the ligands V and thus the characteristics of the SAMFET 10 if an analyte is attached to the receptor groups R connects.

In 7 is shown as in the present embodiment of the ligand in the case of carbon dioxide. Because the receptor groups R the ligands V of the SAMFET 10 Reversibly bind carbon dioxide and release it again and thereby the characteristics of the SAMFETs 10 change, this can be used as a sensor element of a gas sensor for determining the carbon dioxide in the ambient air. Such a sensor can be used in many applications, including medicine.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 2011/0239735 A1 [0002, 0019]

Cited non-patent literature

• A. Ringk, N-Type Self-Assembled Monolayer Field-Effect Transistors and Complementary Inverters, Advanced Functional Materials, Volume 23, Issue 16, 25, 2013, pages 2016-2023 [0015]
• Organic Electronics 14 (2013), 1297-1304 [0016]
• Organic Electronics 11 (2010), 895-898 [0019]

Claims (10)

Ligand (V) for a SAMFET (10), having the following structure $${\text{RS}}^1{\text{-KS}}^2-\text{A}$$

wherein R is a receptor group for an analyte (20), S ¹ and S ^{2 are} independently selected from the group consisting of alkylene groups, perfluorinated alkylene groups and aliphatic ether groups, K is an aromatic or heteroaromatic group, and A is an anchor group for a dielectric ( 12). Ligand (V) after Claim 1 , characterized in that R is selected from the group consisting of -NH ₂ , -OH, -COOH, -SH, C ₂ to C ₁₀ alkenyl groups and aromatic C ₆ to C ₁₈ groups. Ligand (V) after Claim 1 or 2 , characterized in that S ¹ and S ^{2 are} independently selected from the group consisting of C ₂ to C ₂₀ alkylene groups, perfluorinated C ₂ to C ₂₀ alkylene groups, and aliphatic C ₂ to C ₂₀ ether groups. Ligand (V) after one of Claims 1 to 3 , characterized in that K is selected from the group consisting of

wherein each X is H, CN or a C ₁ to C ₁₀ alkyl group and X is the same or different in different units, and wherein n is 0 to 4, p is 0 to 2 and q is 0 to 3. Ligand (V) after one of Claims 1 to 4 characterized in that A is selected from the group consisting of -P (O) Y ¹ Y ² , -C (O) Y ¹ , -SH and -SiY ¹ Y ² Y ³ , wherein Y ¹ , Y ² and Y ^{3 are} independently selected from the group consisting of -OH, -CI, -Br and -OZ, wherein Z is a C ₁ to C ₁₀ alkyl group. SAMFET (10) comprising a gate electrode (11), a dielectric (12) arranged on the gate electrode (11), a source electrode (13) arranged on the dielectric (12), a drain electrode (14) arranged on the dielectric (12) and a self-assembled monomolecular organic layer (15) disposed between the source electrode (13) and the drain electrode (14) on the dielectric (12), characterized in that the organic layer (15) has receptor groups (R) for an analyte (20) , SAMFET (10), after Claim 6 , characterized in that the organic layer (15) ligands (V) according to one of Claims 1 to 5 having. A method for producing a SAMFET (10) according to Claim 6 or 7 , comprising the following steps: - providing (S01) a transistor substrate (30) comprising a gate electrode (11), a dielectric (12) arranged on the gate electrode (11), a source electrode (13) arranged on the dielectric (12) and a drain electrode (14) arranged on the dielectric (12), wetting (S03) at least the dielectric (12) with a solution (42) of a ligand (V) having receptor groups (R) for an analyte (20), and - Heat treating (S04) of the transistor substrate (30). Method, after Claim 8 , characterized in that the ligands (V) ligands according to one of Claims 1 to 5 wherein the anchor groups (A) are anchor groups for the dielectric (12) of the transistor substrate (30). Sensor for detecting an analyte (20), characterized in that it comprises at least one SAMFET (10) according to Claim 6 or 7 whose organic layer (15) has receptor groups (R) for the analyte (20).

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