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Force-sensing capacitors can be used to create low-profile force-sensitive buttons. They have been used in medical imaging to map pressures in the esophagus and to image breast and prostate cancer.
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1262:, Pakrs, Thomas, "High resolution solid state pressure sensor", published 2015-07-14, assigned to Sierra Scientific Instruments Inc
817:
55:. For small deflections, there is a linear relationship between applied force and change in capacitance, which can be shown as follows:
39:
is applied. They are also known as "force-sensitive capacitors". They can provide improved sensitivity and repeatability compared to
1278:
1151:
Martinelli, L; Hurschler, C; Rosenbaum, D (2006-06-01). "Comparison of
Capacitive versus Resistive Joint Contact Stress Sensors".
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540:{\displaystyle C=(\varepsilon Ad_{nominal}+\varepsilon AF/k)/(d_{nominal}^{2}-F^{2}/k^{2})}
200:
252:
173:
is the distance between parallel plates. If the material is linearly elastic (so follows
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800:{\displaystyle \simeq (\varepsilon Ad_{nominal}+\varepsilon AF/k)/(d_{nominal}^{2})}
52:
24:
1328:
1172:
255:. Combining these equations gives the capacitance after an applied force as:
1320:
1221:
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1346:
1180:
32:
1095:
385:
is the separation between parallel plates when no force is applied.
908:{\displaystyle \simeq C_{nominal}+\varepsilon AF/kd_{nominal}^{2}}
51:
Typical force-sensitive capacitors are examples of parallel plate
28:
1384:
1279:"Using Capacitive Force Sensors in Next-Gen Medical Products"
1206:(3rd ed.). Harlow : Longman Scientific & Technical.
1091:
16:
Material whose capacitance changes when a force is applied
43:
but traditionally required more complicated electronics.
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1114:
N. The 8mm SingleTact has a nominal capacitance of 75
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621:{\displaystyle d_{nominal}^{2}>>F^{2}/k^{2}}
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539:
377:
332:
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177:), then the displacement, due to an applied force
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145:
121:
101:
70:
333:{\displaystyle C=\varepsilon A/(d_{nominal}-F/k)}
1122:pF when the rated force is applied. It can be
1094:makes force-sensitive capacitors using moulded
628:, which is true for small deformations where
8:
1303:Egorov, V.; Sarvazyan, A.P. (2008-09-01).
1153:Clinical Orthopaedics and Related Research
1336:
1106:mm thick sensor, with force ranges from 1
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1025:We can express the change in capacitance
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1021:, which is constant for a given sensor.
967:{\displaystyle \simeq C_{nominal}+BF}
7:
1309:IEEE Transactions on Medical Imaging
1233:
1231:
672:{\displaystyle d_{nominal}>>x}
1014:{\displaystyle B=\epsilon A/kd^{2}}
1305:"Mechanical Imaging of the Breast"
1165:10.1097/01.blo.0000218730.59838.6a
1058:
1032:
14:
1204:Principles of measurement systems
102:{\displaystyle \varepsilon A/d}
1126:for direct force measurement.
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327:
282:
153:is the area of the sensor and
1:
122:{\displaystyle \varepsilon }
1076:{\displaystyle \Delta C=BF}
679:, we can simplify this to:
389:This can be rearranged to:
378:{\displaystyle d_{nominal}}
1436:
1118:pF, which increases by 2.2
1283:Medical Design Technology
1202:Bentley, John P. (1995).
41:force-sensitive resistors
1124:mounted on many surfaces
1041:{\displaystyle \Delta C}
1321:10.1109/tmi.2008.922192
1260:US Grant US10961981
21:force-sensing capacitor
1239:"SingleTact Datasheet"
1098:between two layers of
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224:{\displaystyle x=F/k}
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23:is a material whose
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47:Operation principle
1389:www.artannlabs.com
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810:It follows that:
244:{\displaystyle k}
190:{\displaystyle F}
166:{\displaystyle d}
146:{\displaystyle A}
71:{\displaystyle C}
58:The capacitance,
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27:changes when a
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35:or mechanical
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1392:. Retrieved
1388:
1379:
1368:. Retrieved
1364:
1355:
1312:
1308:
1298:
1287:. Retrieved
1285:. 2016-03-01
1282:
1273:
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1245:
1203:
1197:
1156:
1152:
1146:
1133:
1090:
1024:
809:
549:
388:
131:permeability
57:
50:
20:
18:
1361:"SureTouch"
1159:: 214–220.
25:capacitance
1415:Capacitors
1409:Categories
1394:2018-06-21
1370:2018-06-21
1289:2018-06-21
1246:SingleTact
1213:0470234458
1138:References
1092:SingleTact
1087:Production
53:capacitors
1365:SureTouch
1329:0278-0062
1173:0009-921X
1100:polyimide
1059:Δ
1033:Δ
988:ϵ
925:≃
856:ε
822:≃
734:ε
697:ε
691:≃
507:−
446:ε
409:ε
314:−
272:ε
175:Hooks Law
117:ε
86:ε
78:, equals
1347:18753043
1222:30781109
1189:28558376
1181:16672899
1110:N to 450
664:>>
591:>>
340:, where
231:, where
109:, where
33:pressure
1420:Sensors
1338:2581459
1096:silicon
251:is the
1345:
1335:
1327:
1266:
1220:
1210:
1187:
1179:
1171:
1120:
1116:
1112:
1108:
1104:
974:where
37:stress
1242:(PDF)
1185:S2CID
197:, is
29:force
1343:PMID
1325:ISSN
1218:OCLC
1208:ISBN
1177:PMID
1169:ISSN
1130:Uses
1048:as:
1333:PMC
1317:doi
1161:doi
1157:447
129:is
1411::
1387:.
1363:.
1341:.
1331:.
1323:.
1313:27
1311:.
1307:.
1281:.
1244:.
1230:^
1216:.
1183:.
1175:.
1167:.
1155:.
917:C
814:C
683:C
133:,
31:,
19:A
1397:.
1373:.
1349:.
1319::
1292:.
1248:.
1224:.
1191:.
1163::
1071:F
1068:B
1065:=
1062:C
1036:C
1007:2
1003:d
999:k
995:/
991:A
985:=
982:B
962:F
959:B
956:+
951:l
948:a
945:n
942:i
939:m
936:o
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269:=
266:C
239:k
219:k
215:/
211:F
208:=
205:x
185:F
161:d
141:A
97:d
93:/
89:A
66:C
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