WO2008010216A2

WO2008010216A2 - Fetal motor activity monitoring apparatus and pad therfor

Info

Publication number: WO2008010216A2
Application number: PCT/IL2007/000895
Authority: WO
Inventors: Avraham Berger; Avri Hazan
Original assignee: Biopad Ltd
Priority date: 2006-07-18
Filing date: 2007-07-17
Publication date: 2008-01-24
Also published as: WO2008010216A3

Abstract

Fetal motor activity monitoring apparatus including a fetal motor activity sensor and a fetal motor activity determination module for processing time varying information for providing fetal wellbeing information to an expectant mother. The fetal motor activity sensor includes an elongated planar strain gauge film element and a rigidly mounted downward protruding contact for indenting an expectant mother's abdomen on intimate juxtapositioning thereagainst whereupon her transient abdominal movements imparts flexural movements in the fetal motor activity sensor. A two-ply pad including a base sheet for intimate juxtapositioning against an expectant mother's abdomen, and at least one topside pocket overlying the base sheet for slidingly receiving a fetal motor activity sensor therein for bearing against at least a third of the fetal motor activity sensor's topside surface area.

Description

FETAL MOTOR ACTIVITY MONITORING APPARATUS, AND PAD THEREFOR

Field of the Invention

The invention pertains to fetal motor activity monitoring apparatus for providing fetal wellbeing information to an expectant mother and pads therefor.

Background of the Invention

Fetal motor activity has long been recognized as a good predictor of fetal wellbeing as discussed in Fetal Movements In utero - A Review, Sadovsky, E., M.D., Isr. J. Obstet. Gynecol. 1992: 3:27-36. Different types of fetal motor activity are discussed in an article entitled "Classification of human fetal movement" by Ilan Timor-Tritsch, et al., AM. J. Obstet. Gynecol., Volume 126, Number 1, pages 70-77, the contents of which are incorporated herein by reference. Exemplary fetal motor activity includes strong fetal kicks lasting from about ¹A sec to about 1 sec, weak fetal punches lasting upto about ¹A sec, and long fetal rolls lasting from about 10 sec to about 15 sec.

Commonly owned PCT/IL2003/000609 entitled Bio-filter Pad for Facilitating the Detection of an Occurrence of a Physiological Action, and Method Therefor, and Fetal Activity Monitoring Apparatus published under PCT International Publication No. WO 2004/012598 illustrates and describes fetal motor activity monitoring systems suitable for home use for providing information regarding fetal wellbeing based on detecting an expectant mother's abdominal movements as a consequence of fetal motor activity. WO 2004/012598 's Figure 1 shows a fetal motor activity monitoring system 1 including a bio-filter pad 2 adapted for removable intimate adhesion to an expectant mother's abdomen, and having a moving coil transducer 3 centrally disposed thereon for sensing her abdominal movements for providing a visual indication regarding a prevailing level of fetal motor activity. The transducer 3 is connected to a credit-card like, battery powered, fetal motor activity recorder 4 having an amplifier 6, an AfD converter 7, a signal processor 8, a memory 9, an output interface 11, for example, RS-232, and a fetal motor activity display 12 for comparing the prevailing fetal motor activity during a fetal motor activity monitoring session to a regular level of fetal motor activity determined on the basis of historical information. The fetal motor activity recorder 4 may be integrally formed with a transducer 3 together constituting fetal motor activity monitoring apparatus (see WO 2004/012598's page 5, lines 29-30). WO 2004/012598 's Figure 6 shows a fetal motor activity monitoring system 31 similar to the fetal motor activity monitoring system 1 except implemented for telemedicine purposes.

US Patent 4,898,179 to Sirota illustrates and describes a device for detecting, monitoring, displaying and recording of the heartbeats of a pregnant woman and her fetus. In addition, a third sensor can detect movement of the fetus and activate a display of a moving infant or a numerical display of the movement intensity or frequency.

US Patent 5,140,992 to Zuckerwar et al. illustrates and describes an ambulatory passive sensor for use in a fetal motor activity monitoring system. The passive sensor includes a piezoelectric polymer film combined with a metallic mounting plate fastened to a belt and electrically connected to a signal processing unit by means of a shielded cable. The sensor receives pressure pulses emitted from a fetus inside an expectant mother and has means for filtering out pressure pulses arising from other sources such as the maternal heart. The belt is resistant to stretching such that any pressure pulses cause compression of the piezoelectric polymer film thereby affecting its net polarization to produce detectable voltage changes.

Summary of the Invention

The present invention is directed toward fetal motor activity monitoring apparatus including a fetal motor activity sensor sensitive to naturally damped oscillations of transient abdominal displacements including shear waves of an expectant mother's abdomen due to her motor activity including breathing and her fetus' motor activity. Discussion regarding modes of movement of an expectant mother's abdomen can be found in an article entitled: "Mechanical reaction of the front abdominal wall to the impact load during gravidity", Karel Jelen & Antonin Dolezal, Neuroendocrinology Letters Nos. ¹Zz, Feb. -Apr.., Vol. 24, 2003, the contents of which are incorporated herein by reference. Different sections around an expectant mother's abdomen undergo different abdominal displacements in response to the same fetal motor activity, thereby leading to relative abdominal displacements between a pair of spaced apart contact points on her abdomen. The fetal motor activity monitoring apparatus is preferably employed when an expectant mother is reclining for minimizing maternal motor activity except for her breathing, thereby improving detection of fetal motor activity.

Fetal motor activity sensors are preferably deployed to detect expectant mother's relative abdominal displacements along her abdomen's first mode of movement, namely, around her abdomen which demonstrates the largest abdominal movements for most major fetal movements. Alternatively, fetal motor activity sensors can be deployed to detect relative abdominal displacements along generally orthogonal first and second modes of movement. Clinical trials have shown that relative abdominal displacements along an expectant mother's abdomen's first mode of movement typically lie in the range from 0.005mm to 0.05mm depending on fetal age, type of fetal movement, and the like. The fetal motor activity sensors can be generally classified into two types: Cantilever-type fetal motor activity sensors intended for posterior positioning on an expectant mother's abdomen to take advantage of larger relative abdominal displacements for most fetal motor activity than a more anterior position. And beam-type fetal motor activity sensors intended for more anterior positioning on an expectant mother's abdomen which is particularly beneficial during later stage pregnancies by virtue of enabling an expectant mother to look down rather than down and to the side. The fetal motor activity sensors employ one or more planar strain gauge film elements defining a nominal measurement plane in a non-flexed state, and having a variable electrical property responsive to flexing in a transverse direction relative to their measurement planes on application of a bending moment. The fetal motor activity sensors are intended to be intimately juxtaposed against an expectant mother's abdomen such that her transient abdominal movements impart corresponding flexural movements in their strain gauge film elements in a transverse direction to their measurement planes for inducing time varying measurable changes in their variable electrical property. The strain gauge film elements are preferably of the piezoelectric type having a variable electrical charge as a function of flexing. However, other strain gauge technologies may be employed, for example, metallic foil arranged in a grid pattern, and the like.

Commercially available piezoelectric type strain gauge film elements typically demonstrate a linear mechano -electrical conversion of about 12mV/micro strain where micro strain is defined as Δ//L where Δ/ represents deflection from their measurement plane, and L is their length. The strain gauge film elements are typically from about 10mm to about 50 mm in length such that they develop an electrical signal in the order of at least several mVs on sensing small relative abdominal displacements up to about 10OmV on sensing large relative abdominal displacements approaching 0.03mm. By virtue of the strength of this electrical signal, the fetal motor activity monitoring apparatus requires an about 1OdB electrical signal amplification in contrast to the hitherto required 45±5dB electrical signal amplification in the case of commonly owned WO2004/012598. Clinical trials have shown that strain gauge detection of relative abdominal displacements between spaced apart contact points on an expectant mother's abdomen is more efficacious for detecting fetal motor activity than the hitherto moving coil transducer approach.

The fetal motor activity sensors can be directly applied to an expectant mother's abdomen but are preferably used with pads designed to facilitate their operation. The pads are preferably formed with at least one topside pocket for slidingly receiving a fetal motor activity sensor therein, and an underside with a peel off protective liner for exposing a bio-compatible adhesive surface for removable adhesion on an expectant mother's abdomen. A single topside pocket or two or more topside pockets in combination preferably bear against at least a third of a fetal motor activity sensor's topside surface area for ensuring sufficiently dispersed contact pressure of a fetal motor activity sensor against an expectant mother's abdomen. The pads preferably include a base sheet of elastic non-woven fabric for intimate juxtapositioning against an expectant mother's abdomen for attenuating high frequency noise. The one or more topside pockets are also preferably formed from elastic non-woven fabric different than the base sheet's material. The pads preferably include at least one pair of oppositely directed laterally extending wings for improving the detection capability of fetal motor activity sensors by improving their responsiveness to additional abdominal movements to those along an expectant mother's abdomen's first mode of movement.

Brief Description of the Drawings

In order to understand the invention and to see how it can be carried out in practice, preferred embodiments will now be described, by way of non-limiting examples only, with reference to the accompanying drawings in which similar parts are likewise numbered, and in which:

Fig. 1 is a schematic representation of a fetal motor activity monitoring system corresponding to commonly owned PCT International Publication No. WO2004/012598's Figure 1; Fig. 2 is a schematic representation of fetal motor activity monitoring apparatus including a fetal motor activity sensor removably adhered to an expectant mother's abdomen for sensing relative abdominal displacements between a pair of contact points on an expectant mother's abdomen along her abdomen's first mode of movement for providing information regarding fetal wellbeing;

Fig. 3 is a bottom view of Figure 2's fetal motor activity sensor; Fig. 4 is a side view of Figure 2's fetal motor activity sensor; Fig. 5 is a schematic near transverse cross section of Figure 2's expectant mother's abdomen prior to fetal motor activity including a close-up view of the fetal motor activity sensor's protruding contact indenting into her abdomen;

Fig. 6 is a schematic near transverse cross section of Figure 2's expectant mother's abdomen immediately after a strong fetal kick urging her abdomen to the right including a close-up view of the fetal motor activity sensor's protruding contact indenting into her abdomen;

Fig. 7 is a schematic near transverse cross section of Figure 2's expectant mother's abdomen on its return oscillation towards the left including a close-up view of the fetal motor activity sensor's protruding contact indenting into her abdomen;

Fig. 8 is an exemplary graph of an expectant mother's abdomen's relative abdominal displacements in mm against time as sensed by a fetal motor activity sensor's strain gauge film element for a strong fetal kick FK followed by a weak fetal punch FP followed by a slow fetal roll FR; Fig. 9 is an exemplary graph showing strain developed by a fetal motor activity sensor's strain gauge film element in micro-strains against time as a consequence of Figure 8's relative abdominal displacements;

Fig. 10 is an exemplary graph showing time varying information in volts against time as a consequence of Figure 8's relative abdominal displacements; Fig. 11 is a pictorial representation of a fetal motor activity monitoring apparatus inserted into a pad's topside pocket removably adhered to an expectant mother's abdomen for providing time varying information regarding fetal wellbeing; Fig. 12 is an exploded view of a preferred embodiment of Figure 11 's fetal motor activity monitoring apparatus including a cantilever-type fetal motor activity sensor;

Fig. 13 is a top view of Figure 12's fetal motor activity sensor; Fig. 14 is a bottom view of Figure 12's fetal motor activity sensor;

Fig. 15 is a cross section of Figure 12's fetal motor activity monitoring apparatus along line A-A in Figure 11;

Fig. 16 is a cross section of Figure 12's fetal motor activity monitoring apparatus mounted on an expectant mother's abdomen along line A-A in Figure 11;

Fig. 17 is a top view of a preferred embodiment of a beam-type fetal motor activity sensor;

Fig. 18 is a bottom view of Figure 17's beam-type fetal motor activity sensor; Fig. 19 is a cross section of Figure 17's beam-type fetal motor activity sensor along line B-B in Figure 17;

Fig. 20 is a schematic near transverse cross section of an expectant mother's abdomen with Figure 17's beam-type fetal motor activity juxtaposed thereagainst; Fig. 21 is a top view of the alternative embodiment of a beam-type fetal motor activity sensor;

Fig. 22 is a bottom view of Figure 21 's fetal motor activity sensor;

Fig. 23 is a cross section of Figure 21 's beam-type fetal motor activity sensor along line C-C in Figure 21; Fig. 24 is a top view of Figure ll's pad;

Fig. 25 is a bottom view of Figure ll's pad; and

Fig. 26 is a top view of an alternative embodiment of a pad. Detailed Description of Preferred Embodiments of the Present Invention

Figures 2 to 4 show fetal motor activity monitoring apparatus 10 for monitoring relative abdominal displacements between a pair of spaced apart contact points on an expectant mother's abdomen induced by fetal motor activity of sufficient energy for providing fetal wellbeing information to an expectant mother. The fetal motor activity monitoring apparatus 10 includes a cantilever- type fetal motor activity sensor 11 removably adhered onto the expectant mother's abdomen for sensing relative abdominal movements, and a discrete fetal motor activity determination module 12 operatively connected thereto over a wire or wireless communication connection 13. The fetal motor activity sensor 11 is shown deployed at a posterior position for detecting abdominal movements along her abdomen's first mode of movement. The fetal motor activity determination module 12 includes DSP capabilities for processing time varying information from the fetal motor activity sensor 11 due to its flexing as a consequence of relative abdominal movements for determining fetal motor activity. The fetal motor activity determination module 12 includes memory for use as a data logger for inter alia event data logging including event date, event time, event duration, event type, and the like. Alternatively, the fetal motor activity determination module 12 can be cantilever mounted on the fetal motor activity sensor 11.

The fetal motor activity sensor 11 includes a rectangular planar base plate 14 having a base plate topside 16 and a base plate underside 17 for respectively facing away and towards an expectant mother's abdomen. The base plate 14 is preferably formed from a resiliently flexible material, for example, metal, epoxy glass, plastic material, and the like. The base plate 14 has a length of between about 50mm and about 100mm, and a width of between about 30mm and about 60mm. The base plate 14 includes a base plate trailing end 18 and a base plate leading end 19, and the base plate topside 16 has a rectangular elongated planar strain gauge film element 21 deployed lengthwise therealong, and defining a nominal measurement plane MP in its non-flexed state. The strain gauge film element 21 is preferably formed of piezoelectric material, for example, PolyVinylidine DiFluoride (PVDF), and the like. Suitable PVDF material is commercially available from Measurement Specialities, Inc. (MSI), USA, in a range of thicknesses from about 20μm to about lOOμm. The film element 21 is adhered to the base plate 14 by adhesive material such as VHB available from 3M, Inc., USA. The base plate underside's trailing end 17A has a bio-compatible adhesive surface 22 for removable adhesion on an expectant mother's abdomen at a fixed contact point CP_A- Suitable bio-compatible adhesives are commercially available from 3M, Inc., US. The adhesive surface 22 is preferably protected by a manually removable peel away protective liner 23 for manual removal prior to use. The base plate underside's leading end 17B has a downward depending rigidly mounted rounded protruding contact 24 made from suitable bio -compatible material, for example, silicone, and the like, for bearing against an expectant mother's abdomen at a contact point CP_B for indenting same to an indentation depth in the order of about 0.2mm ÷ about 0.5mm. The strain gauge film element 21 has a variable electrical charge as a function of flexion in a transverse direction to the measurement plane MP as denoted by arrow F.

Figures 5 to 7 are schematic transverse cross sections of an expectant mother's abdomen for illustrating operation of the fetal motor activity monitoring apparatus 10 for providing time varying information consequent to a single strong fetal kick to the right. The fetal motor activity sensor 11 is intimately juxtaposed against an expectant mother's abdomen and aligned with her abdomen's first mode of movement. The fetal motor activity sensor 11 is located at a posterior position with its base plate underside's trailing end 17A directed in a posterior direction and its base plate underside's leading end 17B directed in an anterior position. The fetal motor activity sensor 11 is adhered to the expectant mother's abdomen by its adhesive surface 22 at a contact point CP_A whereupon its protruding contact 24 indents her abdomen at a contact point CP_B spaced apart from the contact point CP_A. The strain gauge film element 21 is outwardly flexed in a transverse direction with respect to its measurement plane by the base plate 14 bearing against the expectant mother's abdomen such that the fetal motor activity sensor 11 assumes a nominal flexed state in the absence of fetal motor activity. The protruding contact 24 typically indents into the expectant mother's abdomen by an indentation depth ID in the order of about 0.2mm ÷ about 0.5mm in the absence of fetal motor activity.

Figure 6 shows how a strong fetal kick to the right denoted by arrow A initially urges the expectant mother's abdomen to the right denoted by arrow B such that her abdomen assumes a new lateral position shown in solid lines relative to its initial position shown in dashed lines. The shifting of the expectant mother's abdomen to the right causes the contact point CP_B to move to the right through a greater displacement than the contact point CPA thereby reducing the outward flexing of the fetal motor activity sensor 11 relative to its initial flexed state. Typically, the contact point CP_A moves to the right from its initial position by about 0.01mm ÷ 0.02mm whilst the contact point CP_B moves to the right from its initial position by about 0.03mm ÷ 0.05mm subsequent to a strong fetal kick to the right. Consequently, the protruding contact 24 indents less into the expectant mother's abdomen. The strain gauge film element 21 still remains outwardly flexed but to a lesser degree than in its initial flexed state. Figure 7 shows the damped oscillation of the expectant mother's abdomen to the left denoted by arrow C after the aforesaid strong fetal kick to the right to assume a new lateral position shown in solid lines relative to its initial position shown in dashed lines. The shifting of the expectant mother's abdomen to the left causes the contact point CP_B to move more to the left than the contact point CPA thereby increasing the outward flexing of the fetal motor activity sensor 11 relative to its initial flexed state. The absolute increase in flexing of the fetal motor activity sensor 11 in the second oscillation is typically less than the absolute decrease in the first oscillation towards the right by virtue of dissipation of some of the energy transferred to the expectant mother's abdomen by the fetal kick. In mathematical notation, |ID_T1-ID₀| > |IDτ₂-ID₀| where |ID_Ti-ID₀| is the absolute relative abdominal displacement between the contact points CP_A and CP_B subsequent to the first abdominal displacement to the right relative to the initial abdomen position at T₀ and 1ID_T2-ID₀I is the absolute relative abdominal displacement between the contact points CP_A and CP_B in the second abdominal displacement to the left relative to the initial abdomen position at T₀.

Figures 8 to 10 show exemplary graphs of an expectant mother's abdomen's relative abdominal displacements in mm against time, the corresponding strain developed by a fetal motor activity sensor's strain gauge film element as a consequence of her relative abdominal displacements in micro- strains against time, and the corresponding information signal in volts against time after filtering out maternal breathing. The graphs depict a strong fetal kick denoted FK followed by a weak fetal punch denoted FP followed by a slow fetal roll denoted FR. The nominal outward flexion of a strain gauge film element on a stationary expectant mother's abdomen leads to a DC like information signal which is typically offset such that the information signal is preferably zero irrespective of the degree of a nominal outward flexion.

Figure 11 shows fetal motor activity monitoring apparatus 41 for use with a generally oval shaped pad 100 for removable intimate adhesion on an expectant mother's abdomen. The fetal motor activity monitoring apparatus 41 is similar to the fetal motor activity monitoring apparatus 10 insofar as it is designed to monitor relative abdominal displacements between spaced apart contact points on an expectant mother's abdomen.

Figures 12 to 16 show the fetal motor activity monitoring apparatus 41 includes a cantilever-type fetal motor activity sensor 42 integrally formed with a fetal motor activity determination module 43. The fetal motor activity sensor 42 includes a rectangular planar base plate 46 having a base plate topside 47 and a base plate underside 48 for respectively facing away from and towards an expectant mother's abdomen. The base plate 46 is preferably formed from a resiliently flexible material, for example, metal, epoxy glass, plastic material, and the like. The base plate 46 has a length L of between about 50mm and about 100mm, and a width W of between about 30mm and about 60mm. The base plate 46 has a base plate trailing end 49 and a base plate leading end 51, and is formed with a pair of L-shaped slits 52 along its long sides disposed toward the base plate trailing end 49 for defining a major base plate portion 53 and a minor inverted T-shaped base plate portion 54 resiliently flexible relative thereto along an imaginary lateral fold line 56 about a third along the base plate 46 from the base plate trailing end 49.

The base plate topside 47 has a rectangular planar strain gauge film element 57 similar to the strain gauge film element 21. The strain gauge film element 57 is deployed lengthwise on the base plate topside 47 from the base plate trailing end 49 extending toward the middle of the major base plate portion 53. The strain gauge film element 57 defines a measurement plane MP in its non-flexed state. The major base plate portion 53 has four supports 58 at its corners for supporting a cover 59 in a spaced apart manner for attenuating external noise for improving sensitivity of the fetal motor activity sensor 42 to relative abdominal displacements. The remaining area of the major base plate portion 53 is used for components of the fetal motor activity determination module 43. The base plate underside 48 is provided with three downward depending rigidly mounted protruding contacts 61, 62 and 63 at the base plate trailing end 49, the base plate leading end 51, and at the imaginary fold line 56 for bearing against an expectant mother's abdomen at contact points CP_A, CP_B and CPQ, respectively. The leading protruding contact 62 has a height Hl and the trailing protruding contact 61 and the intermediate protruding contact 63 have a height H2 relative to the measurement plane MP where H1>H2 such that the former more deeply indents an expectant mother's abdomen than the latter on juxtaposing the base plate 46 thereagainst. The provision of the intermediate protruding contact 63 affords a lever like arrangement which increases relative abdominal displacements by a factor L_BC/L_AC where L_BC is the separation between the leading protruding contact 62 and the intermediate protruding contact 63, and L_Ac is the separation between the trailing protruding contact 61 and the intermediate protruding contact 63.

Figures 17 to 19 and Figures 21 to 23 respectively show beam-type fetal motor activity sensors 70 and 71 intended for deployment in more anterior positions than the cantilever-type fetal activity motor sensors. The beam-type fetal motor activity sensors 70 and 71 include a base plate 72 with a base plate topside 73 and a base plate underside 74 for respectively facing away from and toward an expectant mother's abdomen. The base plates 72 have a pair of weakened regions 76 defining a major base plate surround 77 and a minor base plate beam 78 supported at its opposite ends for resilient elastic bowing with respect to their major base plate surround 77 on application of a force thereagainst in a direction perpendicular to the base plate 72. The weakened regions 76 are preferably constituted by a pair of parallel and opposite scored lines for reducing the thickness of base plate 72 or throughgoing slits. Alternatively, the weakened regions 76 may be slightly arcuate. The beam-type fetal motor activity sensors 70 and 71 can be oval or circular for use with similarly shaped pads.

The base plate topside 73 can be provided with a single elongated planar strain gauge film element 79 typically deployed midway along its minor base plate beam 78 (see Figures 17 to 19) or a pair of spaced apart elongated panar strain gauge film elements 81 deployed towards opposite ends of its minor base plate beam 78 (see Figures 21 to 23). The strain gauge film elements 79 and 81 define measurement planes MP in their non-flexed states. The base plate underside 74 is formed with a beam protruding contact 82 midway along its minor base plate beam 78, and at least one surround protruding contact circumferentially disposed around the minor base plate beam 78. The surround protruding contacts can be in the form of four surround protruding contacts 83 (see Figures 17 to 19), a single continuous peripheral surround protruding contact 84 (see Figures 21 to 23), and the like. The beam protruding contact 82 has a height H3 relative to the measurement plane MP and the surround protruding contacts 83 and 84 have a height H4 with respect thereto where H3>H4. The fetal motor activity sensor 70 's base plate underside 74 can be fitted with the fetal motor activity sensor 71's single continuous peripheral surround protruding contact 84. The fetal motor activity sensor 71 's base plate underside 74 can be fitted with the fetal motor activity sensor 70's four surround protruding contacts 83.

The fetal motor activity sensors 70 and 71 are intended to be juxtaposed against an expectant mother's abdomen at opposite ends, for example, by a pad 116 (see Figure 26) such that they their minor base plate beam 78 undergo flexure along three regions on juxtapositioning against an expectant mother's abdomen, namely, its midway region and its two extreme ends. Consequently, the fetal motor activity sensors 70 and 71's effectively behave as a pair of fetal motor activity sensors in series. The strain gauge film element 79 affords a stronger signal than counterpart cantilever like embodiments. Deployment of a pair of strain gauge film elements 81 as opposed to a single strain gauge film element 79 provides phase information which can be employed for providing information including inter alia the direction of travel of an abdominal displacement, the speed of propagation of a shear wave traveling along an expectant mother's abdomen, and the like. Figures 24 and 25 show the pad 100 has a longitudinal axis 101, a lateral midline 102, an oval shaped base sheet 103 for intimate juxtapositioning against an expectant mother's abdomen, and a generally semi-circular topside pocket 104 overlying the base sheet 103 in an upright orientation relative to the longitudinal axis 101 and extending toward the lateral midline 102. The topside pocket 104 is shaped and dimensioned to slidingly receiving the fetal motor activity apparatus 41 therein for bearing against at least a third of the fetal motor activity sensor's topside surface area so as to ensure sufficient sensitivity to transient abdominal displacements.

Both the base sheet 103 and the topside pocket 104 are preferably formed from non-woven fabric for attenuating high frequency noise. The topside pocket 104 is typically formed from different fabric than the base sheet 103. Suitable non-woven fabric is commercially available from N. R. Spuntech Industries Ltd, Israel. The base sheet 103 has a bio-compatible adhesive underside surface 106 for removable adhesion to an expectant mother's abdomen. The adhesive underside surface 106 is preferably protected by a peel away protective liner 107 for manual removal prior to use. The pocket 104 is preferably ultra-sound soldered to the base sheet 103. An elongated strip 108 is mounted widthwise midway along the pocket 104 to form a pair of oppositely directed laterally extending wings 109 with end tabs 111. The end tabs' undersides 112 each have a bio -compatible adhesive surface 113 for removable adhesion to an expectant mother's abdomen. The adhesive surfaces 113 are preferably each protected by a peel away protective liner 114 for manual removal prior to use. Suitable biocompatible adhesives are commercially available from 3M, Inc., US.

Figure 26 shows a pad 116 similar in construction and use as the pad 100 but differing therefrom insofar that the former has a pair of generally semicircular opposite topside pockets 117 with openings 118 facing one another for slidingly receiving opposite ends of fetal motor activity monitoring apparatus 41, and two pairs of oppositely directed laterally extending wings 119 each terminating at an end tab 121 similar to the end tabs 111.

While the invention has been described with respect to a limited number of embodiments, it will be appreciated that many variations, modifications, and other applications of the invention can be made within the scope of the appended claims.

Claims

Claims:

1. Fetal motor activity monitoring apparatus for providing fetal wellbeing information to an expectant mother, the apparatus comprising: (a) a fetal motor activity sensor having a base plate with a base plate topside and a base plate underside for respectively facing away from and towards an expectant mother's abdomen, said base plate topside having at least one elongated planar strain gauge film element defining a nominal measurement plane in a non-flexed state, and having a variable electrical property proportional to resilient elastic flexion in a transverse direction to said measurement plane on application of a bending moment, said base plate underside having at least one rigidly mounted downward depending rounded protruding contact for indenting an expectant mother's abdomen on intimately juxtapositioning said base plate underside thereagainst whereupon said at least one planar strain gauge film element assumes a nominal flexed state in the absence of fetal motor activity whereby transient abdominal movements of the expectant mother's abdomen impart flexural movements in said transverse direction for inducing corresponding changes in said variable electrical property; and

(b) a fetal motor activity determination module for processing time varying information from said fetal motor activity sensor for determining fetal motor activity inducing at least some of said transient abdominal movements for providing fetal wellbeing information to the expectant mother.

2. Apparatus according to claim 1 wherein said base plate includes a base plate trailing end and a base plate leading end intended to be resiliently elastically flexed relative to said base plate trailing end for rendering a cantilever-type fetal motor activity sensor, and said base plate underside's leading end has a leading protruding contact having a height Hl relative to said measurement plane for indenting an expectant mother's abdomen on intimately juxtapositioning said base plate underside thereagainst.

3. Apparatus according to claim 2 wherein said base plate trailing end is removably adhered to an expectant mother's abdomen.

4. Apparatus according to claim 2 wherein said base plate trailing end includes a trailing protruding contact have a height H2 relative to said measurement plane where H1>H2.

5. Apparatus according to claim 4 and further comprising an intermediate protruding contact between said trailing protruding contact and said leading protruding contact, and adjacent said trailing protruding contact and remote from said leading protruding contact, thereby rendering a leverage arrangement.

6. Apparatus according to any one of claims 2 to 5 wherein said cantilever- type arrangement is facilitated by a pair of oppositely directed slits for forming a major portion and a minor portion resiliently elastically flexible relative to said major portion at an imaginary lateral fold line, and said at least one elongated strain gauge film element extends across said imaginary lateral fold line.

7. Apparatus according to any one of claims 2 to 6 and further comprising a cover mounted on said base plate in a spaced apart manner.

8. Apparatus according to claim 1 wherein said base plate includes a pair of weakened regions for defining a major base plate surround supporting a minor base plate beam at its opposite ends for resilient elastic flexion relative to said major base plate surround for rendering a beam-like fetal motor activity sensor, said base plate underside includes a beam protruding contact midway along said minor base plate beam, and having a height H3 relative to said measurement plane for indenting an expectant mother's abdomen on intimately juxtapositioning said base plate underside thereagainst, and said base plate underside includes at least one surround protruding contact circumferentially disposed with respect to said minor base plate beam and having a height H4 relative to said measurement plane for indenting an expectant mother's abdomen on intimately juxtapositioning said base plate underside thereagainst wherein H3>H4.

9. Apparatus according to claim 8 wherein said at least one surround protruding contact includes at least four surround protruding contacts circumferentially disposed with respect to said minor base plate beam.

10. Apparatus according to claim 8 wherein said at least one surround protruding contact includes a single substantially continuous peripheral surround protruding circumferentially disposed with respect to said minor base plate beam.

11. Apparatus according to claim 8 wherein said at least one surround protruding contact includes a single substantially continuous peripheral surround protruding circumferentially disposed with respect to said minor base plate beam.

12. Apparatus according to any one of claims 8 to 11 wherein said base plate topside has a pair of spaced apart planar strain gauge film elements responsive to flexion of said beam for providing phase information regarding said transient abdominal movements.

13. Apparatus according to any one of claims 8 to 12 wherein said pair of weakened regions are constituted by a pair of throughgoing slits.

14. Apparatus according to any one of claims 8 to 13 and further comprising a cover mounted on said base plate in a spaced apart manner.

15. A two-ply pad for use with a fetal motor activity sensor for sensing abdominal movements of an expectant mother's abdomen, the fetal motor activity sensor having a topside and an underside for respectively facing away from and towards the expectant mother's abdomen, the topside defining a topside surface area, the pad comprising a base sheet for intimate juxtapositioning against the expectant mother's abdomen, and at least one topside pocket overlying said base sheet for slidingly receiving the fetal motor activity sensor therein for bearing against at least a third of the fetal motor activity sensor's topside surface area.

16. The pad according to claim 15 wherein said base sheet is formed from elastic non-woven fabric.

17. The pad according to claim 16 wherein said at least one topside pocket is formed from elastic non- woven fabric different from said base sheet's said elastic non-woven fabric.

18. The pad according to any one of claims 15 to 17 and further comprising a pair of opposite topside pockets having openings facing one another.

19. The pad according to any one of claims 15 to 18 and further comprising at least one pair of oppositely directed laterally extending wings terminating at end tabs each having an underside with a bio-compatible adhesive surface for removable adhesion on an expectant mother's abdomen.