       NOTE: This disposition is nonprecedential.

  United States Court of Appeals
      for the Federal Circuit
              __________________________

     ALCOHOL MONITORING SYSTEMS, INC.,
              Plaintiff-Appellant,
                           v.
   ACTSOFT, INC., OHIO HOUSE MONITORING
   SYSTEMS, INC., and US HOME DETENTION
       SYSTEMS AND EQUIPMENT, INC.,
              Defendants-Appellees.
              __________________________

                      2010-1250
              __________________________

    Appeal from the United States District Court for the
District of Colorado in consolidated case Nos. 07-CV-2261
and 08-CV-1226, Judge Philip A. Brimmer.
               ___________________________

               Decided: January 24, 2011
              ___________________________

    MICHAEL G. MARTIN, Lathrop & Gage, LLP, of Denver,
Colorado, argued for plaintiff-appellant. With him on the
brief were PHILLIPS S. LORENZO and JAMES E. DALLNER.

   KYLE B. FLEMING, Renner, Otto, Boisselle & Sklar,
LLP, of Cleveland, Ohio, argued for defendants-appellees.
With him on the brief were TODD R. TUCKER and
ALCOHOL MONITORING   v. ACTSOFT                           2


NICHOLAS J. GINGO. Of counsel on the brief were RICHARD
E. FEE and KATHLEEN M. WADE, Fee & Jefferies, P.A., of
Tampa, Florida.
              __________________________

Before LOURIE, CLEVENGER, and MOORE, Circuit Judges.
MOORE, Circuit Judge.


    Alcohol Monitoring Systems, Inc. (AMS) appeals the
district court’s grant of summary judgment that defen-
dants Actsoft, Inc. (Actsoft), Ohio House Monitoring
Systems Inc. (Ohio House), and U.S. Home Detention
Systems and Equipment, Inc. (U.S. Home) (collectively,
Defendants) do not infringe the asserted claims of U.S.
Patent No. 5,220,919 (’919 patent). Because the district
court based its grant of summary judgment on an errone-
ous claim construction and genuine issues of material fact
preclude summary judgment of infringement under the
doctrine of equivalents, we affirm-in-part, reverse-in-part,
and remand.
                       BACKGROUND
    The ’919 patent is entitled “Blood Alcohol Monitor”
and discloses a device and methods of operating a device
that securely attaches to a human subject and monitors
blood alcohol levels by determining the alcohol levels
expelled through a subject’s skin. The device is useful for
monitoring the consumption of alcohol in individuals
under house arrest or in alcohol rehabilitation programs.
    The liver metabolizes most of the alcohol ingested by
a human. Water compartments in the skin, however, also
absorb small amounts of alcohol, which the skin later
emits through insensible perspiration. Measuring the
alcohol levels expelled through a subject’s skin is known
3                           ALCOHOL MONITORING    v. ACTSOFT


as transdermal alcohol monitoring. Transdermal alcohol
levels are not the same as blood alcohol levels, which one
measures from a blood sample using gas chromatography.
However, “measuring the amount of ethanol at a prede-
termined distance away from the subject’s skin . . . pro-
vides an indication of the relative amount of ethanol in
the subject’s blood.” ’919 patent col.3 ll.27-31.
    One measures transdermal alcohol levels by sampling
the air near a subject’s skin with a transdermal alcohol
sensor. Id. col.6 ll. 48-66. The alcohol sensor creates an
electrical current and the voltage of that electrical current
is proportional to the amount of alcohol present in the
sampled air. Id. col.6 ll.59-62. Through the use of con-
version factors, one can convert this voltage and calculate
a transdermal alcohol concentration (TAC) that approxi-
mates blood alcohol content (BAC). Id. col.11 ll.28-38.
Claim 14 of the ’919 patent is at issue in this appeal:
    14. A method for monitoring the percentage of
        blood alcohol content of a human subject,
        said method comprising the steps of:
        (a) securely attaching an alcohol meas-
            urement device to the human subject
            using an attachment device;
        (b) storing an error indication if the hu-
            man subject tampers with said meas-
            urement device or an error occurs
            within said measurement device;
        (c) measuring a percentage of alcohol ex-
            pelled through the subject’s skin into
            said measurement device and storing
            a measurement result;
        (d) repeating steps (b) and (c) until a pre-
            determined amount of time expires;
ALCOHOL MONITORING   v. ACTSOFT                           4


       (e) transmitting each of said measure-
           ment results and each of said tamper
           and error indications to said monitor-
           ing station; and
       (f) repeating steps (b) through (e).
    AMS markets the SCRAM device, which it considers a
preferred embodiment of the ’919 patent. The SCRAM
device not only measures the voltage produced by the
alcohol emitted through the subject’s skin, but also con-
verts the voltage measurement to a TAC value that
approximates a percentage BAC. 1
    On October 25, 2007, AMS asserted the ’919 patent
against Actsoft and Ohio House for the sale of the House
Arrest Solution (HAS) device. AMS later added U.S.
Home as a defendant. The HAS device includes an ankle
bracelet with a gas sensor that measures the voltage
produced by the alcohol emitted through a subject’s skin,
but does not calculate TAC or any other percentage.
Every fifteen minutes, the HAS device takes four voltage
measurements. The measurement result stored and
transmitted by the HAS device is a scaled, average volt-
age reading calculated by a proprietary formula. Defen-
dants refer to this calculated variable as “fValc,” which is
a decimal average of the four voltage measurements.
    On December 30, 2008, defendants Actsoft and Ohio
House moved for summary judgment of noninfringement
and invalidity. On April 27, 2009 the district court issued
an Order Regarding Claim Construction. Alcohol Moni-
toring Sys. Inc. v. Actsoft, Inc., Civil Action Nos. 07-cv-

   1     BAC is the amount of alcohol per fixed unit of
blood and is normally defined as grams of ethanol per
deciliter of blood (g/dL). This BAC is also defined as a
percentage of the weight of ethanol per volume of blood (%
w/v).
5                           ALCOHOL MONITORING   v. ACTSOFT


02261, 08-cv-01226-PAB-MJW, 2009 WL 1120113 (D.
Colo. Apr. 27, 2009) (Markman Order). The district court
construed the disputed terms, two of which are at issue in
this appeal – steps (c) and (e). Id. at *7.
    The district court held that step (c) of claim 14 re-
quired “the measurement of the amount of alcohol being
emitted from an individual’s skin and the calculation of a
percentage of blood alcohol content.” Id. The district
court noted that the specification consistently referred to
the invention as measuring blood alcohol content. Id. at
*4-5. For example, the specification alternatively de-
scribes the invention as: a “method to passively test the
blood alcohol content of a human subject;” “perform[ing]
testing which indicates the blood alcohol content of a
human subject;” and “provid[ing] for the continuous
monitoring of a subject’s blood alcohol level by measuring
the level of ethanol that has been expelled through the
subject’s skin.” Id. at *5. The district court noted that
the specification contains an example of how to calculate
blood alcohol content after measuring a sample with a
sensor that measures voltage. Id. at *4-5.
   The district court further found that its construction
was supported by the preamble of claim 14:
    Step (c) contemplates more than the mere ascer-
    taining of the amount of alcohol emitted from a
    person’s skin. Some calculation or series of calcu-
    lations must take place which lead to the identi-
    fied percentage. It is true that Step (c) does not
    indicate literally that the calculation undergone at
    this stage arrives at a measure of blood alcohol
    content. However, . . . Claim 14 as a whole does
    indicate that such a calculation is to occur; its
    preambulatory language explains that the inven-
    tion consists of a ‘method for monitoring the per-
ALCOHOL MONITORING   v. ACTSOFT                            6


   centage of blood alcohol content of a human sub-
   ject.’ It is axiomatic that a device could not ‘moni-
   tor’ one’s percentage of blood alcohol content
   without first determining what that percentage is.
Id. at *4 (internal citations omitted). The district court
also determined that its construction was supported by
the testimony of AMS’s expert J. Robert Zettl who stated
that the term “percentage of alcohol” in step (c) meant
“blood alcohol concentration.” Id. at *4.
    The district court construed step (e) to require
“transmitting every indication from Step (b) and every
measurement from Step (c) in a way that the individual
indications and measurements are separately identifi-
able.” Id. at *7. The district court relied on a dictionary
defining “each” as “being one of two or more distinct
individuals having a similar relation and often constitut-
ing an aggregate.” Id.
    On April 28, 2009, the district court, ruling from the
bench, granted the motion for summary judgment of
noninfringement. Alcohol Monitoring Sys. Inc. v. Actsoft,
Inc., Civil Action Nos. 07-cv-02261, 08-cv-01226-PAB-
MJW, Document Number 210 at 10 (D. Colo. Apr. 28,
2009) (Opinion). The district court noted that AMS
conceded that literal infringement was not possible given
the court’s claim construction because the HAS device
does not calculate a percentage of BAC. Op. at 5. The
district court also held that the HAS device did not in-
fringe under the doctrine of equivalents, because the “use
of an alcohol sensor that provides nothing more than a
voltage output equivalent to the amount of alcohol emit-
ted from the subject’s skin is not the substantial equiva-
lent of calculating a percentage of blood alcohol content.”
Op. at 8. The district court determined that measuring
the voltage alone is neither the substantially same func-
7                           ALCOHOL MONITORING   v. ACTSOFT


tion nor yields the substantially same result as determin-
ing a percentage of BAC. Op. at 8-9.
    AMS appeals, challenging the court’s claim construc-
tion and judgment of noninfringement. We have jurisdic-
tion pursuant to 28 U.S.C. § 1295(a)(1).
                       DISCUSSION
    Infringement, either literal or under the doctrine of
equivalents, is a question of fact. IMS Tech., Inc. v. Haas
Automation, Inc., 206 F.3d 1422, 1429 (Fed. Cir. 2000).
An infringement analysis is a two-step inquiry: first the
court must construe the claims, and second the court
must apply the properly construed claims to the accused
device. See, e.g., Acumed L.L.C. v. Stryker Corp., 483 F.3d
800, 804 (Fed. Cir. 2007). We review both the district
court’s grant of summary judgment of noninfringement
and its underlying claim construction de novo. Laryngeal
Mask Co. Ltd. v. Ambu A/S, 618 F.3d 1367, 1370 (Fed.
Cir. 2010). “Summary judgment is appropriate when
there is no genuine issue as to any material fact and the
moving party is entitled to judgment as a matter of law.”
Immunocept, L.L.C. v. Fulbright & Jaworski L.L.P., 504
F.3d 1281, 1286 (Fed. Cir. 2007). In making this deter-
mination, this court views the record in the light most
favorable to the non-moving party. See Anderson v.
Liberty Lobby, Inc., 477 U.S. 242, 255 (1986).
                  I. Claim Construction
    Generally, we give claim terms their ordinary and
customary meaning, which is the meaning a person of
ordinary skill in the art would give to the term at the time
of invention when read in the context of the specification
and prosecution history. See Phillips v. AWH Corp., 415
F.3d 1303, 1313 (Fed. Cir. 2005) (en banc).
ALCOHOL MONITORING    v. ACTSOFT                            8


                            A. Step (c)

     AMS argues that step (c) does not require the “calcu-
lation of a percentage of blood alcohol content.” We agree.
AMS asserts that the district court improperly treated the
preamble language “monitoring the percentage of blood
alcohol content” as a limitation by requiring a calculation
of BAC in step (c). Generally, a preamble does not limit
the scope of claims unless “it recites essential structure or
steps, or if it is necessary to give life, meaning, and vital-
ity to the claim.” See, e.g., Am. Med. Sys., Inc. v. Biolitec,
Inc., 618 F.3d 1354, 1358 (Fed. Cir. 2010) (internal cita-
tions omitted). We previously held that a preamble is not
limiting where it “merely gives a descriptive name to the
set of limitations in the body of the claim that completely
set forth the invention.” IMS Tech., Inc., 206 F.3d at
1434-35 (Fed. Cir. 2000). Here, “monitoring the percent-
age of blood alcohol” is such a descriptive name and does
not additionally limit the scope of the claims.
     Furthermore, the district court’s construction of step
(c) is difficult to reconcile with the fact that devices that
measure alcohol emitted through the skin do not actually
calculate a BAC, but instead calculate a TAC, which
approximates BAC. The plain language of the claim,
“percentage of alcohol expelled through the subject’s
skin,” indicates that the measurement is not BAC, which
is only measured by a blood sample, but instead is TAC.
Indeed, Defendants admit that the claimed method calcu-
lates TAC, a percentage that provides an indication of
BAC. Therefore, to the extent the claim requires a calcu-
lation of a percentage, that percentage only approximates
BAC (e.g., TAC).
    However, AMS further contends that the term “per-
centage” does not require any calculation, but instead is a
“percentage of alcohol expelled through the subject’s skin
9                           ALCOHOL MONITORING    v. ACTSOFT


into said measurement device.” In other words, AMS
contends that the term refers to the measured sample,
which is not all of the alcohol expelled through the sub-
ject’s skin, but only the “percentage” that enters “into said
measurement device.”
    Under AMS’s proposed construction, the “percentage”
is not a quantifiable measurement. A person of skill in
the art would be unable to calculate what “percentage” of
alcohol went into the measurement device, compared to
the total alcohol expelled through the body in its entirety.
Even if the device could conceivably quantify the amount
of alcohol entering into the device, the device could not
determine the total quantity of alcohol expelled through
the body.
     Because AMS’s proposed construction is not quantifi-
able, it conflicts with claims 19 and 21, which depend
from claim 14. Claims 19 and 21 require storing an
interferant indication “if a change in said percentage of
alcohol exceeds a predetermined . . . rate.” It logically
follows that the claimed percentage must itself be a
numerical value or one could not compare “a change in
said percentage” to “a predetermined rate” as required by
the dependent claims. Therefore, claim 14 requires the
actual calculation of a percentage and AMS’s proposed
construction cannot be correct.
    Thus, properly construed, step (c) requires the meas-
urement of an amount of alcohol being emitted from an
individual’s skin and the calculation of a percentage that
approximates blood alcohol content (e.g., transdermal
alcohol content). This construction is consistent with both
the intrinsic record and the extrinsic testimony from
AMS’s inventor and expert witness.
ALCOHOL MONITORING   v. ACTSOFT                           10


                            B. Step (e)

    AMS contends that the district court improperly con-
strued step (e) to require transmitting “in a way that the
individual indications and measurements are separately
identifiable” based solely on the HAS device and the
Defendants’ noninfringement arguments. AMS further
argues that the district court’s construction is inappropri-
ate because it confuses “measurement” with the claimed
“measurement result.” Defendants argue that the district
court did not construe step (e) solely in light of the HAS
device, but instead relied on the plain meaning of “each.”
    We agree with AMS that the district court appears to
have conflated the measurement of a percentage and the
claimed “measurement result.” Step (e) requires “trans-
mitting each of said measurement results and each of said
tamper and error indications to said monitoring station.”
We note that this “measurement result” may or may not
be the same as the measured “percentage” of step (c). The
claim does not require the storage and transmission of
“said percentage” but instead introduces a new limitation:
“a measurement result.” While the claimed “measure-
ment result” could be the calculated “percentage” it could
also be an indicator that the human subject has consumed
alcohol or any other result capable of storage and trans-
mission. These are two separate limitations and may or
may not include the same information. Therefore, prop-
erly construed step (e) should refer not to a “measure-
ment” but instead to a “measurement result.”
    Regarding the “separately identifiable” language of
the district court’s construction, the district court clearly
relied on the plain meaning of “each” and not the accused
device as AMS alleges. We agree with the district court
that the plain meaning of “each” is defined as “being one
of two or more distinct individuals having a similar rela-
11                          ALCOHOL MONITORING   v. ACTSOFT


tion and often constituting an aggregate.” Markman
Order at 13 (citing Merriam-Webster’s Collegiate Diction-
ary 390 (11th ed. 2007)). Thus, step (e) as properly con-
strued requires transmitting every measurement result
from step (c) in a way that the measurement results are
separately identifiable.”
                     II. Infringement
    “To prove literal infringement, the patentee must
show that the accused device contains every limitation in
the asserted claims.” Mas-Hamilton Grp. v. La-Gard,
Inc., 156 F.3d 1206, 1211 (Fed. Cir. 1998). To find in-
fringement under the doctrine of equivalents, any differ-
ences between the claimed invention and the accused
product must be insubstantial. Graver Tank & Mfg. Co.
v. Linde Air Prods. Co., 339 U.S. 605, 608 (1950). One
way of proving infringement under the doctrine of equiva-
lents “is by showing on a limitation by limitation basis
that the accused product performs substantially the same
function in substantially the same way with substantially
the same result as each claim limitation of the patented
product.” See, e.g., Crown Packaging Tech., Inc. v. Rexam
Beverage Can Co., 559 F.3d 1308, 1312 (Fed. Cir. 2009).
     It is undisputed that the HAS device does not calcu-
late TAC or any percentage that approximates BAC, but
merely measures voltage. Therefore, under the proper
claim construction of step (c), the HAS device does not
literally infringe claim 14 of the ’919 patent.
    With regard to the doctrine of equivalents, AMS ar-
gues that the district court failed to provide step (c) with
any equivalents, because it required a calculation of a
percentage that is included in the literal scope of the
claims. AMS argues that this is reversible error, because
a reasonable jury could conclude that the HAS device
infringes under the doctrine of equivalents because its
ALCOHOL MONITORING   v. ACTSOFT                        12


quantitative voltage measurement is equivalent to a
calculation of a percentage TAC. AMS contends that both
the measured voltage and the calculated percentage
increase with increased alcohol consumption. AMS ar-
gues that to convert the measured voltage in the HAS
device to a percentage of alcohol one must only use a
simple mathematical equation. Thus, AMS argues that
the only difference between the measured voltage and a
calculated percentage of alcohol is the unit of measure-
ment.
    Defendants argue that voltage is not substantially the
same result as obtaining a percentage TAC. Defendants
contend that the ultimate goal of transdermal alcohol
monitoring is to obtain an approximate BAC and voltage
alone, without more, is insufficient to calculate TAC.
Defendants contend that even if there is a simple formula
or algorithm to convert the HAS device’s voltage to a
percentage TAC, there is no evidence that the HAS device
performs such a calculation.
    Under the facts before us, a reasonable jury could
conclude that the HAS device’s voltage measurements
perform substantially the same function, in substantially
the same way, to achieve substantially the same result as
the calculation of a percentage TAC. Therefore, the
district court erred in granting summary judgment of
noninfringement under the doctrine of equivalents.
    Defendants argue that they are separately entitled to
summary judgment of noninfringement because the HAS
device either does not perform step (d) or step (e). We
decline to address these arguments for the first time on
appeal. See Superguide Corp. v. DirecTV, Inc., 358 F.3d
870, 884 (Fed. Cir. 2004) (declining to address infringe-
ment theories not addressed by district court’s summary
judgment decision). Now that we have properly construed
13                          ALCOHOL MONITORING   v. ACTSOFT


the disputed terms, the parties will be in a better position
to brief these issues to the district court.
                        CONCLUSION
     For the reasons discussed above, we affirm the dis-
trict court’s grant of summary judgment of no literal
infringement, reverse the district court’s grant of sum-
mary judgment of no infringement under the doctrine of
equivalents and remand.
 AFFIRMED-IN-PART, REVERSED-IN-PART, AND
               REMANDED
                           COSTS
     Each party shall bear its own costs.
