TEWLS EXAM PACKAGE |ACTUAL EXAM QUESTIONS WITH DETAILED VERIFIED
ANSWERS (100% CORRECT ANSWERS) |UPDATED VERSION |/ALREADY GRADE
A+
1.What is the measurement of TEWL? - ANSWER The flux of water diffusing through the stratum
corneum from viable epidermis to the surface
2.what is flux? - ANSWER the mass of water per unit of area and per unit of time
3.what do TEWL instruments measure? - ANSWER it measures the flux of water in the adjacent air and it
can come from TEWL, SSWL and perspiration
4.what limitations does the open chamber method suffer from? - ANSWER 1. vulnerable to disturbance
from ambient air movements
2. angular dependence
3. calibration inconsistency
4. temperature and contact dependence
5.what is diffusion? - ANSWER Diffusion is the net movement of molecules (particles) from a region of
high concentration (chemical potential) to a region of low concentration as a result of random thermal
motion.
6.what is the advantage of condenser-chamber method? - ANSWER it eliminates disturbance from
ambient air movements
7.where are the two humidity values calculated from? - ANSWER 1. from the readings of the relative
humidity and temperature sensors mounted on the chamber wall
2. from the condenser where its calculated from temperature (without another RH sensor needed)
8.the peak at short times is caused by what? - ANSWER 1. ambient humidity entering the measurement
chamber before sealing against the skin
2. unbound skin surface water
,9.when is the TEWL measurement ended - ANSWER automatically by the software when user-set target
precision is reached
10.what is the area under the curve - ANSWER represent the evaporated quality by transient flux via:
1. ambient transient
2.SSWL
11.what prevents unnecessary ice buildup when using the aqua flux? - ANSWER the black rubber stopper
in the parking receptacle closes the measurement chamber when not in use
12.what is probe angular dependence? - ANSWER readings remain within 1% SD when the probe is help
correctly
13.does pressure affect probe measurements? - ANSWER no it does not
14.what is the condenser role in TEWL closed chamber method? - ANSWER Vapour sink
controls microclimate
15.What do the RH & T sensors do? - ANSWER used to sense vapour flux
16.what does skin stripping do to TEWL? - ANSWER It perturbs the steady-state water distribution with
the SC and the skin needs to re-acclimatise before measuring TEWL. About 10 minutes in reality but
theoretically 1 hour.
17.how does the condenser chamber method work? - ANSWER water evaporates from skin surface. It
diffuses to cold condenser (-7.6C) where it is trapped as ice.
humidity is high at skin surface and low at condenser. This gradient is used to measure vapour flux
density of water.
18.how do you prime the condenser? - ANSWER Priming is the ice crystal nucleation initiated by
mechanical disturbance.
, Tap & scribe with blank end of a clean sock-tip swab for 10-15 seconds.
19.what is sealed and non-sealed parking positions? - ANSWER sealed = condenser is cold, it is on
measurement mode, the seal keeps out ambient humidity
non-sealed = condenser is warm, it is on off & stand-by modes
open to allow melted water to escape
20.what must the participants do to prepare themselves for TEWL measurement? - ANSWER do not eat,
consumer caffeine drinks or smoke
do not perform vigorous physical exercise prior
follow study centre advice on: washing
topical use of products
use of medicines
21what are the acclimatisation conditions? - ANSWER time: 15-30 min prior to measurement
ambient conditions:
temperature: 20-22C
humidity: less than 60%, less is better
air: moving over exposed skin sites (use a fan to circulate air in room)
22.what activities lead to invalid measurement? - ANSWER Sweat gland activity
imperfect seal with skin
sliding probe
premature lift-off
23.topical products contaminate measurement caps, this contamination can get into chamber by? -
ANSWER parking stopper, swabs, in-situ cleaning
24.As the TEWl measurement progresses in time what happens to the 5 second period difference value?
- ANSWER the value decreases
ANSWERS (100% CORRECT ANSWERS) |UPDATED VERSION |/ALREADY GRADE
A+
1.What is the measurement of TEWL? - ANSWER The flux of water diffusing through the stratum
corneum from viable epidermis to the surface
2.what is flux? - ANSWER the mass of water per unit of area and per unit of time
3.what do TEWL instruments measure? - ANSWER it measures the flux of water in the adjacent air and it
can come from TEWL, SSWL and perspiration
4.what limitations does the open chamber method suffer from? - ANSWER 1. vulnerable to disturbance
from ambient air movements
2. angular dependence
3. calibration inconsistency
4. temperature and contact dependence
5.what is diffusion? - ANSWER Diffusion is the net movement of molecules (particles) from a region of
high concentration (chemical potential) to a region of low concentration as a result of random thermal
motion.
6.what is the advantage of condenser-chamber method? - ANSWER it eliminates disturbance from
ambient air movements
7.where are the two humidity values calculated from? - ANSWER 1. from the readings of the relative
humidity and temperature sensors mounted on the chamber wall
2. from the condenser where its calculated from temperature (without another RH sensor needed)
8.the peak at short times is caused by what? - ANSWER 1. ambient humidity entering the measurement
chamber before sealing against the skin
2. unbound skin surface water
,9.when is the TEWL measurement ended - ANSWER automatically by the software when user-set target
precision is reached
10.what is the area under the curve - ANSWER represent the evaporated quality by transient flux via:
1. ambient transient
2.SSWL
11.what prevents unnecessary ice buildup when using the aqua flux? - ANSWER the black rubber stopper
in the parking receptacle closes the measurement chamber when not in use
12.what is probe angular dependence? - ANSWER readings remain within 1% SD when the probe is help
correctly
13.does pressure affect probe measurements? - ANSWER no it does not
14.what is the condenser role in TEWL closed chamber method? - ANSWER Vapour sink
controls microclimate
15.What do the RH & T sensors do? - ANSWER used to sense vapour flux
16.what does skin stripping do to TEWL? - ANSWER It perturbs the steady-state water distribution with
the SC and the skin needs to re-acclimatise before measuring TEWL. About 10 minutes in reality but
theoretically 1 hour.
17.how does the condenser chamber method work? - ANSWER water evaporates from skin surface. It
diffuses to cold condenser (-7.6C) where it is trapped as ice.
humidity is high at skin surface and low at condenser. This gradient is used to measure vapour flux
density of water.
18.how do you prime the condenser? - ANSWER Priming is the ice crystal nucleation initiated by
mechanical disturbance.
, Tap & scribe with blank end of a clean sock-tip swab for 10-15 seconds.
19.what is sealed and non-sealed parking positions? - ANSWER sealed = condenser is cold, it is on
measurement mode, the seal keeps out ambient humidity
non-sealed = condenser is warm, it is on off & stand-by modes
open to allow melted water to escape
20.what must the participants do to prepare themselves for TEWL measurement? - ANSWER do not eat,
consumer caffeine drinks or smoke
do not perform vigorous physical exercise prior
follow study centre advice on: washing
topical use of products
use of medicines
21what are the acclimatisation conditions? - ANSWER time: 15-30 min prior to measurement
ambient conditions:
temperature: 20-22C
humidity: less than 60%, less is better
air: moving over exposed skin sites (use a fan to circulate air in room)
22.what activities lead to invalid measurement? - ANSWER Sweat gland activity
imperfect seal with skin
sliding probe
premature lift-off
23.topical products contaminate measurement caps, this contamination can get into chamber by? -
ANSWER parking stopper, swabs, in-situ cleaning
24.As the TEWl measurement progresses in time what happens to the 5 second period difference value?
- ANSWER the value decreases
