Wednesday, March 15, 2023 Our attempt at e-EQE Paper B 2023 - Strips for testing blood sugar

Here's our attempt at this year's paper B. This year's paper concerned strips for testing blood sugar levels and devices that use them. The paper was not very mechanical, with the main feature for claim 1 being a range. Some hard decisions were expected from the candidates regarding the novelty of the claims in light of a 54(3) document. 

You can find our solution by clicking on "Read more" below.

We look forward to your comments!

Comments are welcome in any official EPO language, not just English. So, comments in German and French are also very welcome!

Please do not post your comments anonymously - it is allowed, but it makes responding more difficult and rather clumsy ("Dear Mr/Mrs/Ms Anonymous of 15-03-2023 22:23"), whereas using your real name or a nickname is more personal, more interesting and makes a more attractive conversation. You do not need to log in or make an account - it is OK to just put your (nick) name at the end of your post.

The first objection of the Examiner that we need to address is the alleged lack of novelty of Claim 1. Comparing Claim 1 as filed with D1 shows that all features are disclosed there, so we'll need to amend. Fortunately, the client provides us with a proposal: strike the word 'hydrophilic', and incorporate claim 2. 

Striking 'hydrophilic' from the claim is a broadening of the claim. This would be allowed if this passed the gold standard: could the skilled person have derived non-hydrophilic embodiments from the application? Although hydrophilic is nowhere explained as essential, there seems to be no indication that hydrophilic is optional either. Accordingly, this suggestion of the client seems to be added subject matter. Perhaps, Bad Sugar PLC, can file a new application for their hydrophobic strips, as none of the cited art discloses such strips either.

Incorporating claim 2 into claim 1 is not added subject matter, though one could wonder about striking the part 'the smallest pore diameter', but as the pore sizes tapers from large to small, this seems to be implied by the claim 2 text. When in doubt you could leave this part of claim 1, it should not make much of a difference. 

The real question is, is the claim that we get novel over the cited art. For D1 this is not a problem as the tapering of pore size is not in D1. D2 however discloses all of new Claim 1 (note the capillary in D2's claims), except for feature (c) 'an opening for measurement and putting into place the strip, the opening being present in the reagent part'. 

There are two spots in D2 where one could wonder if they disclose feature (c). 

The first one is in D2, [03], which has a reference to D1. D1 does disclose feature (c). In principle, it is allowed for a prior art document to reference another document (gl. G-IV, 8), but this reference seems to have problems. First, it is not clear from D2 that this reference is even meant to fill-in the disclosure of their embodiment. Section [03] merely describes the prior art, not the new embodiments of D2. Second, the disclosure is specific for blood separation, not on the opening, or even blood sugar measurement. So, D2, [03], seems not enough. 

The second spot in D2 is section [06]. Here it is disclosed that D2's strip can be used in 'conventional devices for blood sugar measurement'. All the conventional devices that we know of, and in particular, the one referred to in D1, have feature (c). So one might argue that feature (c) is implicitly disclosed in D2. However, the bar for implicit disclosure is a high one, it should be inevitable that a conventional device has the opening. It's not my technical field, but I guess other options are possible. So section [06] is also not enough. 

This means that this amendment of the client makes Claim 1 novel. There was a small antecedent error in Claim 1, which we have also corrected. 

Inventiveness needs to be argued, but as there is only one 54(2) document this seems straightforward. 

For Claim 2, as it is now in Claim 1, the normal approach would be to strike the claim. But as the claim is there, we've opted to amend it to a fallback range, restricting the diameter on the upper membrane. This would make the claim novel over D2 even if the D2 as whole might be considered as incorporating feature (c) from D1. We don't think this amendment is needed. 

Claim 3 contains an error which the client wants to have corrected. The legal basis for this correction would be R.139, second sentence. We need to ask if it is immediately evident that  an error has occurred, and what the correction should be (gl. H-VI, 2.2.1). That an error has occurred seems obvious; drawing 3-5 ml of blood from a finger seems a serious injury. The examiner seems to agree with this. We'll argue that the units, not the values are wrong, using common general knowledge of a droplet as evidenced by an article in Blood Science and Technology, that we'll file with our letter. Auxiliary reference can also be made D1 as further evidence.  

Claim 4 did not need amendments.

Claim 5 as filed is not novel, as existing devices are suitable for the new strips as well. In the application there a new device is disclosed specially suited for the new strips. Although the new device uses a known spectrophotometer, the combination with an opening for inserting the strip seems to be novel. As to the amendment itself one could doubt whether the 'array detector' needs to be incorporated in the amended claim 5. As the description seems to state that this is the only option, we've included it in the claim. 

There are other ways to make claim 5 novel. For example, one could turn claim 5 into a use claim ('use of device for measuring blood') in this way the suitability becomes a hard feature. Alternatively, one could try a kit claim that has the strip and the device. But as both of these options get their inventiveness from the strip, the scope of protection does not appear to be improved for the client. 

For claims 1 and 5 we also need to address R.43(2), and maybe unity as well. For the former, we'll argue that the claims fall under the exception of R.43(2)(a) plurality of interrelated products. This is an example, of a plug and socket claim (gl. F-IV, 3.2). 

Our claim amendments are thus:

1. Strip for measuring blood sugar levels, comprising:
(a) a reagent part comprising a membrane
(b) a capillary for transporting a blood sample to thea reagent part
(c) an opening for measurement and putting into place the strip, the opening being present in the reagent part;
characterised in that the membrane is a hydrophilic membrane in which the pores of the membrane taper in diameter from 30 to 100 µm on the upper membrane surface to 0.1 to 5 µm on the lowerhaving a smallest pore diameter of between 0.1 and 5 µm.

2. Strip according to claim 1 in which the pores of the membrane taper in diameter
from 30 to 100 µm on the upper lower membrane surface to taper in diameter from 0.13 to 15 µm on the lower.

3. Strip according to claims 1 or 2 that can perform a measurement on a blood sample of 3 to 5 µlml.

4. Strip according to any of claims 1 to 3 in which the reagent is attached to the strip using adhesive.

5. Device for measuring blood sugar levels for use with a strip as defined in claims 1 to 4, comprising an opening for inserting the strip, and a spectrophotometer, which uses an array detector, which is able to detect light of several wavelengths, including a wavelength of 635 nm and an additional wavelength to perform the measurement.

Edit 15/3: removed duplicate 'uses' in claim 5

We look forward to your comments!

Sander, Jelle, Roel

 (c) DeltaPatents

Annex  - the complete paper - copied from Wiseflow "EPO – EQE Compendium" (added 16/3/2023)

NB: when copying, the line numbering, table and formatting of the amended claims got lost - we did a best-effort reformatting of the table and the amended claims. Please click on the figures for a full-size view.

EUROPEAN QUALIFYING EXAMINATION 2023

Paper B

This paper comprises:

* Description of the application
* Claims
* Drawings of the application (pre-printable)
* Communication
* Document D1  (pre-printable)
* Document D2  (pre-printable)
* Client‘s letter
* Amended claims

 

* Description of the application

Description of the application

[001] Diabetes is a long-term condition that arises because of changes in the way in
which insulin is produced and used. Insulin is a hormone that facilitates the uptake of
glucose by cells to produce energy and promotes the storage of glucose as glycogen.
Lack of insulin causes the levels of blood glucose to rise, with potentially life-threatening
results.

[002] To mitigate the consequences of diabetes, people with the condition should
measure their blood glucose level two to seven times a day, depending on the nature
and severity of their individual case. Based on the observed pattern in the measured
glucose levels, the patient and physician can together make adjustments in diet,
exercise and insulin intake to better manage the disease. The measured glucose levels
should be available to the patient immediately, through the use of a simple-to-use meter
and strip system that is rapid, inexpensive, and accurate.

[003] The most commonly-used systems for determining blood sugar levels comprise a
strip which is inserted in a device for the determination of blood sugar level. The patient
puts a droplet of blood on the strip, which is then analysed in the device. The blood can
be transported within the strip by several mechanisms. The most usual and preferred
method is by capillary action. This mechanism is used in most devices on the market
today. Capillary action is the drawing of a liquid into a narrow tube of the strip.

[004] Figures 1A and 1B show the strip, Figure 1A being a view from above, and Figure
1B a view from below. The strip (1) has a reagent part comprising a membrane (2). An
opening (3) allows a light source to access the reagent part. A droplet of blood is applied
at (4), which is transported to the reagent part by capillary action along a capillary (5).
The shape of the opening (3) is chosen such that the strip clicks into place in the
measurement device. Figure 2 shows a detailed view of the membrane (2). Pores (6)
extend through the membrane from the upper to the lower surface. The representation
of the pores is schematic. The actual number of pores is much larger.

[005] Glucose cannot be measured directly but needs to be converted in the strip.
First, the strip separates red blood cells from the rest of the blood. The rest of the blood,
mostly plasma, reacts with two different reagents in the strip to generate a colour that
can be analysed by a spectrophotometer. This works as follows. The plasma first reacts
with an enzyme called glucose oxidase, which generates hydrogen peroxide and
gluconic acid from the glucose in the blood. The hydrogen peroxide then reacts with a
dye system to generate the colour. The colour intensity is linearly dependent on the
amount of hydrogen peroxide and thus on the amount of glucose in the blood. All of
these reagents are well known in the art and can be obtained commercially, for example
from Glucosic Inc.

[006] The colour is analysed by measuring the intensity of light that is reflected when the
colour is exposed to the light source. The measurement is performed using a
spectrophotometer. A spectrophotometer is an instrument used to determine the relative
intensity of various wavelengths in a spectrum of light. In the present case, the relative
intensity is measured at a wavelength of 635 nm.

[007] Before the reaction can take place, the blood needs to be separated so that the
red blood cells are separated from the plasma. The separation should take place with as
little as possible cell lysis, which is the breaking of cells. Such broken cells influence the
measurement in the spectrophotometer. Also, as few as possible red blood cells should
remain in the plasma, because these red blood cells have a negative influence on the
light measurement as well.

[008] We have now devised a membrane that separates the red blood cells in a very
effective way, while at the same time almost completely avoiding cell lysis. This means
that the analysis can be done with less blood. This is an advantage for older people who
often release very little blood from their fingers and who often need, with current
systems, a second or third try to release sufficient blood for a reliable measurement.

[009] A membrane is a solid structure with pores. Some components of a liquid mixture
can pass through the pores, whereas others cannot, thus performing the separation. A
membrane like ours is able to separate red blood cells from a blood sample. What
remains after the separation is the glucose-containing plasma. To achieve this
separation, the membrane needs to have suitable pore sizes. In general, the smallest
pore sizes used have a diameter from 0.1 to 5 µm. In a preferred embodiment, the
membrane does not have a uniform pore size, but a pore size that tapers in diameter
from the upper to the lower membrane surface. For example, pore diameter may taper
from 100 µm on the upper membrane surface to about 0.1 µm on the lower. On the
upper surface, the pore size is preferably in the range 30 µm to 40 µm. The pore size on
the lower surface is preferably in the range 0.1 to 1.0 µm, with a pore size of 0.3 to
1.0 µm being preferred. Optimum results are obtained at a pore size in the range of 0.4
to 0.6 µm.

[010] The optimum pore size of 0.5 µm is a balance between separation efficacy and
separation speed. When the pore size is 0.1 µm the separation is best, but the
separation takes a relatively long time, which is disadvantageous for the user of the
device. In the examples, we always use a membrane with a smallest pore size of 0.5
µm, but any pore size of between 0.1 and 1.0 µm can be used.

[011] The membranes are hydrophilic, which means that they have affinity for aqueous
(water-based) media. They are preferably made of polyamides. A well-known polyamide
is nylon. Most types of nylon are suitable for use in the strip of the invention. The
membranes as such are known and are normally used in micro-filtration in general. The
membranes are commercially available, for example from Permembrane Inc.

[012] Membranes where the pore diameters taper from the upper to the lower
membrane surface have several advantages. Most importantly, the red blood cells can
be separated from the plasma with less breaking of the red blood cells, i.e. the above
mentioned cell lysis. Cell lysis can be avoided by having a gentle gradient of the pore
diameter in the membrane. The membrane may have a first pore diameter of 100 µm
that tapers to the smallest diameter of 0.5 µm. The gentlest separation, with least cell
lysis, would be achieved when the diameter changes over a long distance, i.e. across a
thick membrane. However, such a thick membrane would have a high pressure drop,
which also has an influence on the cell lysis. We have tested several membranes and
have found that a membrane thickness of 150 to 400 µm provides a good balance
between pressure drop and separation efficacy.

[013] When using the membrane with a pore-size gradient, the sample contains fewer
broken cells and, therefore, a new measurement device can be used that is especially
adapted for strips using this membrane. This device uses a special spectrophotometer
that uses an array detector, which is able to detect light of several wavelengths. A
monochromator, as used in the prior art devices, is no longer necessary. This makes the
measurement more accurate, because measurements at two wavelengths can be
compared, resulting in a more accurate measurement. The measurement is still at a
wavelength of 635 nm, but an additional wavelength can be used to increase the
accuracy. Such a spectrophotometer is schematically illustrated in Figure 3. These
spectrophotometers are known as such but have not previously been used in devices for
measurement of sugar levels in blood.

[014] The strips using a membrane with pore-size gradient can also be used with a
conventional measurement device, but in that case a little more blood is needed for the
measurement, but still less than with a uniform pore-size membrane. The new
measurement device described here can only be used with the strips of the present
invention.

[015] The table below shows how the density of the plasma produced after separation of
red blood cells is influenced by the structure of the membrane. The presence of red
blood cells in the plasma increases its density and so indicates less effective separation
by the membrane. All membranes have the same thickness and when the pore diameter
changes over its thickness, it changes in linear fashion. This linear change is not
essential, however.

	Pore diameter (µm)	Density (mg/ml)
Membrane A	0,5	961
Membrane B	4	1017
Membrane C	100 to 0.5	920
Membrane D	40 to 0.5	921
Membrane E	35 to 0.5	918

 

[016] It is clear from the table that membranes with a gradient of pore diameters result in
plasma with a lower density, which indicates that very few of the red blood cells
permeate the membrane.

[017] In operation, the test strip is first mounted in the device, prior to application of the
blood sample. Then, a glucose-containing blood sample, typically obtained by a finger
puncture (small prick in the fingertip) is applied to the test strip. The amount of blood
should exceed that needed to saturate the reagent part comprising the membrane in the
area where light reflectance will be measured. This amount is at least 3 ml, or the
amount of one droplet. A droplet from a healthy adult is about 5 ml, but older people
usually have less blood in a droplet. After the sample is applied, the measurement starts
automatically when the fluid has permeated the membrane, and the device detects the
resulting change in light reflectance of the testing surface.

[018] The test strips of the present invention can be used in conventional instruments,
such as the Sugar Level Pro™ or the Glucexact™. However, when combined with our
improved instrument, as described above, we can achieve a reliable measurement with
very small amounts of blood.

[019] By using a membrane with a gradient described above, less cell lysis takes place.
This means that the plasma that is obtained contains fewer impurities from the red blood
cells that can influence the measurement. A more accurate measurement can be
performed on a smaller blood sample, especially when the strip is used with the
improved device.

* Claims

Claims

1. Strip for measuring blood sugar levels, comprising:
(a) a reagent part comprising a membrane
(b) a capillary for transporting a blood sample to a reagent part
(c) an opening for measurement and putting into place the strip, the opening
being present in the reagent part;
characterised in that the membrane is a hydrophilic membrane having a smallest
pore diameter of between 0.1 and 5 µm.

2. Strip according to claim 1 in which the pores of the membrane taper in diameter
from 30 to 100 µm on the upper membrane surface to 0.1 to 5 µm on the lower.

3. Strip according to claims 1 or 2 that can perform a measurement on a blood
sample of 3 to 5 ml.

4. Strip according to any of claims 1 to 3 in which the reagent is attached to the
strip using adhesive.

5. Device for measuring blood sugar levels for use with a strip as defined in claims 1
to 4, comprising an opening for inserting the strip, and a spectrophotometer,
which uses a wavelength of 635 nm to perform the measurement.


* Drawings of the application (pre-printable)

* Communication

Communication

1. The examination is based on the application as originally filed. Document D1 is prior
art in accordance with Article 54(2) EPC. Document D2, which was pending on the date
of filing of the present application, is prior art in view of Article 54(3) EPC.

2. The subject-matter of claims 1, 3 to 5 is not novel within the meaning of Articles 54(1)
and (2) EPC because it is known from D1.
D1 discloses a strip and a device for determining glucose levels in a blood sample. The
strip comprises a polyamide membrane with a pore diameter of between 0.1 and 5 µm.

3. The subject-matter of claims 1 to 5 is not novel within the meaning of Articles 54(1)
and (3) EPC because it is known from D2.

D2 discloses a strip for determining glucose levels in a blood sample. The strip
comprises a membrane with pores that taper in diameter from the upper membrane
surface to the lower. The pore sizes vary from 200 µm to 0.1 µm. The larger size is
preferably 30 to 100 µm. The smallest pore size should be between 0.1 and 5 µm. The
membrane is a hydrophilic membrane. The strip can be used in devices for measuring
sugar level based on light intensity.

4. In claim 3 it is specified that the measurement can be performed on 3 to 5 ml. It would
appear that either the value or the unit is wrong, or both. The same mistake is made in
paragraph [017]. An explanation is requested.

5. Claims 1 and 5 do not fulfil the requirements of Rule 43(2) EPC.
Claims 1 and 5 are both independent device claims. Such a claims structure having two
independent claims in the same category is not allowable.

6. To maintain the application, new claims should be filed which take the above
objections into account. Care should be taken to ensure that the new claims comply with
the requirements of the EPC in respect of clarity, novelty, and inventive step (Art. 84, 54
and 56 EPC). Any amendments should not introduce subject matter which extends
beyond the content of the application as originally filed (Art. 123(2) EPC).

7. In the letter of reply, the problem-solution approach should be followed. In particular,
the difference between the new claims and the prior art disclosed in D1 and D2, the
objective technical problem underlying the invention in view of the closest prior art, and
the solution thereto should be indicated. The basis in the application as originally filed for
the amendments should be indicated (Art. 123(2) EPC and Rule 137(4) EPC).

* Document D1 (pre-printable)

Document D1: GB1234321

Description

[001] Easy and accurate measurement of glucose levels in blood is very important. A
person with diabetes needs to monitor their glucose levels up to seven times a day.
Based on this measurement, the amount of insulin to be injected is determined. The
measurement should be quick and accurate. As the measurement has to be performed
several times a day, it is impractical that such a measurement is performed by a medical
professional. The measurement should be what is known as a lay-operator
measurement, preferably performed by the patient.

[002] There are many systems currently on the market that can perform such
measurements. However, most of these measurements require several manipulations by
the user. However, in the last years a new type of system has taken over the market.
This is a system in which a disposable strip is placed in a measurement device. A
droplet of blood is placed on the strip and is analysed in the device. A droplet of blood
has a volume of at least 5 µl.

[003] Such a strip is illustrated in Figures 1A and 1B. Figure 1A shows the strip from
above, whereas Figure 1B shows the strip from below. The strip (1) has a reagent
part (2), which is attached to the strip using adhesive. Opening (3) is for access of the
light source to the reagent part. A droplet of blood is applied at (4), which is transported
to the reagent part by capillary action along a capillary (5). The strip is inserted in the
device with the side of the reagent part first. The shape of the opening (3) is chosen,
such that the strip clicks into place.

[004] The device comprises an opening for inserting the strip, and a spectrophotometer,
which measures light intensity at 635 nm. The spectrophotometer comprises a light source,
a monochromator, a sample compartment, and a detector, as shown in Figure 2.

[005] The present invention concerns the reagent strip. On the one hand, this strip
separates red blood cells from the rest of the blood. The rest of the blood, mostly
plasma, reacts with two different reagents to generate a colour that can be analysed by
a spectrophotometer. The plasma first reacts with an enzyme called peroxidase, which
generates hydrogen peroxide from the glucose in the blood. The hydrogen peroxide then
reacts with a dye system to generate the colour. The colour intensity is linearly
determined by the amount of hydrogen peroxide and thus by the amount of glucose in
the blood.

[006] The reagent strip comprises a membrane that separates the red blood cells from
the rest of the blood and comprises reagents that react with the permeate to make the
sugar level visible. The reagents are as described above. The membrane is made of a
hydrophilic material. Preferably, polyamide membranes are used, such as nylon. The
membranes have a smallest pore diameter of 0.1 to 5 µm. At these pore diameters, a
good separation of red blood cells from the plasma is possible without too much lysis of
the cells.

Claims

1. Strip for measuring blood sugar levels, comprising a capillary and a hydrophilic
membrane having a smallest pore diameter of between 0.1 and 5 µm.

2. Device for measuring blood sugar levels for use with a strip as defined in claim 1,
comprising an opening for inserting the strip, and a spectrophotometer, which performs
measurement at 635 nm.

 

* Document D2 (pre-printable)

Document D2: EP1234567 (Article 54(3) EPC)

Description

[001] This application is concerned with a membrane that is used in devices for the
measurement of blood sugar levels, mostly for people with diabetes.

[002] To mitigate the consequences of diabetes, people with the condition should
measure their blood glucose level two to seven times a day, depending on the nature
and severity of their individual case. Based on the observed pattern in the measured
glucose levels, the patient and physician together make adjustments in diet, exercise
and insulin intake to better manage the disease. The measured glucose levels should be
available to the patient immediately, through the use of a simple-to-use meter and strip
system that is rapid, inexpensive, and accurate.

[003] For such measurements to be performed, it is necessary that the red blood cells
are separated from the rest of the blood, so that the plasma is retained. The sugar level
measurements are performed on the plasma. GB1234321 teaches us to separate the
blood using a membrane. These membranes have a constant pore size. Good
separation of the red blood cells is reported. However, it was found that some cell lysis
takes place. This means that some red blood cells break apart. These parts will also
pass the membrane and influence the measurement of the sugar level.

[004] We have now found an improved membrane that avoids most of the lysis of the
red blood-cells. In addition, the improved membrane leads to a more accurate
measurement of the sugar level. Our improved membrane does not have a uniform pore
size, but has a gradient of pore size, from large to small. Membranes may have pores
that taper in diameter from 200 µm on the upper membrane surface to 0.1 µm on the
lower. On the upper surface, the pore size is preferably in the range of 30 µm to 100 µm.
On the lower surface, the smallest pore size ranges from 0.1 to 5 µm. The membranes
have a thickness of around 200 µm. The membrane should not be too thick, otherwise
the pressure drop through the membrane will be too high.

[005] The membrane can be any kind of hydrophilic membrane, i.e. a membrane that
has affinity with water.

[006] The membrane can be used in known strips, which can in turn be used in
conventional devices for blood sugar measurement. In these devices, glucose level is
measured by measuring light intensity at a wavelength of 635 nm. The measurement is
performed using a spectrophotometer.

[007] The colour that is measured based on the light intensity is generated by an
oxidation reaction in the strip. The strip contains an enzyme, glucose oxidase, which
oxidises the glucose to gluconic acid and hydrogen peroxide. The hydrogen peroxide
then reacts with a dye to produce a colour. The colour intensity is a measure of the
amount of glucose in the blood.

Claims

1. Membrane for use in a strip for measuring blood sugar levels, which is hydrophilic
and which is characterised in that the membrane has pores that taper in diameter from
200 µm on the upper membrane surface to 0.1 µm on the lower.

2. Strip for measuring blood sugar levels, comprising a capillary and a membrane as
defined in claim 1.

(No Figures in D2)

* Client‘s letter

Client’s letter

To: Ms Cyrille Ringe

Dear Ms Ringe,

We have reviewed the EPO communication and provide you in the following with what is
hopefully a helpful basis for filing a response to that communication. We have also
attached a new set of claims that we believe overcome the objections raised by the
examiner. We restricted our claims to the membranes with a pore-size gradient.
However, we leave it to you to decide on the final wording of the claims, as long as these
claims cover the strip and the device.

We are currently testing membranes that are different from the polyamides of the
examples. Most of the promising membranes are hydrophilic, but some hydrophobic
membranes also show promise in the separation of red blood cells. The claims should
preferably cover the possibility of membranes other than polyamides. We have deleted
the term “hydrophilic” in claim 1. We believe that the fact that the membrane is
hydrophilic is not essential.

Concerning claim 4, directed to the device, we believe that further amendment is not
necessary as the claim refers to the novel strip of claim 1.

The communication states that the claims are not novel over D2. We don’t think this
objection is correct, because document D2 is an earlier application from our own
company. We don’t think we should be penalised in this application for a previous
development of our own technology.

Finally, the examiner noticed an editorial error in claim 3 and in the description. In
claim 3 and in paragraph [017], the amount of liquid is indicated to be in ml. This should
have been in µl. This should be clear from the context in paragraph [017], which refers to
the volume of a droplet. Also, document D1 as cited by the examiner shows that the
amounts used in similar devices are in the range of µl and not ml. Also, D1 refers to a
droplet. In addition, we attach an extract from Blood Science and Technology, which
shows that blood droplets are always in the range of 1 to 5 µl. This is a well-regarded
publication in the technical field.

We will be on our annual retreat on Bora Bora and will not have internet access or be
contactable by phone. Please file a response reflecting the wishes we have indicated
above.

Kind regards,

Dr. Keith Richards
Bad Sugar PLC
2023/B/EN/19

Annex to the Client’s letter

Blood Science and Technology

Blood droplets

The volume of blood droplets is relevant because blood droplets are often used in
medical analysis. When the finger of a healthy adult is pricked, the droplets have a
volume of 5 µl. Persons aged 65 and over often have less blood available when pricked,
usually less than 4 µl or even 3 µl.

 

* Amended claims

1. Strip for measuring blood sugar levels, comprising:
(a) a reagent part comprising a membrane
(b) a capillary for transporting a blood sample to a reagent part
(c) an opening for measurement and putting into place the strip, the opening
being present in the reagent part;
characterised in that the membrane is a hydrophilic membrane having a smallest
pore diameter of between 0.1 and 5 µm. having pores that taper in diameter from 30 to 100 µm on the upper membrane surface to 0.1 to 5 µm on the lower.

2. Strip according to claim 1 in which the pores of the membrane taper in diameter
from 30 to 100 µm on the upper membrane surface to 0.1 to 5 µm on the lower.

3.2. Strip according to claims claim 1 or 2 that can perform a measurement on a blood
sample of 3 to 5 ml ul.

4.3. Strip according to any of claims 1 to 2 3 in which the reagent is attached to the
strip using adhesive.

5.4. Device for measuring blood sugar levels for use with a strip as defined in claims 1
to 43, comprising an opening for inserting the strip, and a spectrophotometer,
which uses a wavelength of 635 nm to perform the measurement.