Field of the Invention

This particular invention, Pinch Grip Biofeedback Device is meant to establish an accurate, precise, portable and advanced device which can give real time measurements based on pinch grip span. It measures the amount of force generation by index finger and thumb individually in pounds (lbs) with a wider grip span (5.5 cms), designed according to feasibility so that it can be used in even low cost set ups in physiotherapy.

This particular invention can be used for measuring the pinch grip strength for normal healthy individuals as well as can be used to train people who cannot produce sustained contraction with thumb and index finger such as in various musculoskeletal diseases and after hand injury and surgery. It can be used as a treatment device for the stroke population for training hand function.

The device houses a Hand Held Assembly made of custom made plastic box and Sensor Assembly with microcontroller, USB facility. So it is handy and easy to carry for the therapist and the same device can be used for treatment and evaluation.

Background of the Invention
Major functions of hand entail gripping, manipulation and expression used to perform various daily living activities and fine works like drawing, writing, holding objects like pencil, spoon, fork, key and many more. Humans have two unique hand grips: power and precision grip. In Prehension, Grip is the ability of hand to hold objects between thumb and fingers distinguishing human hand from primates. Precision/ prehension grip includes 3 sorts of grips, namely tip to tip, pad to pad, and side to pad.

It is widely accepted that grip and pinch strength (PS) measurements provide an objective index of functional integrity of upper extremity and helps in determining the efficacy of different treatment strategies for hand and reevaluating patient progress.

Repetitive, awkward and high pinch grip exertions are related to fatigue, discomfort and injury to wrist and hand complex in industrial populations.

The effects of pinch grip exertions on the intrinsic muscles of the hand need to be considered.

The biomechanical properties and characteristics of pinch grip exertions should be considered to design principles and intervention strategies to reduce fatigue, discomfort and chances of injury to upper limb.
Various factors affect grip strength, such as anthropometric factors namely height, weight, Body Mass Index, hand dominance and occupation. Hand anthropometry plays an important role and is used in designing objects dealing with human hands. One among those factors that also can be of influence is hand size, but no specific adaptation is used to adapt the dynamometer pinch grip span to the hand size. Grip span affects pinch grip strength it has been shown in studies done in boys and girls aged year 16 -20, teenagers and adult population.

Even these principles can be used to design device being used to measure pinch grip.
Only few studies are available which attempted to quantify the relationship between pinch grip span and pinch grip strength.

All these studies {(Fathallah, Kroemer, and Waldron, 1991), Imrhan and Rahman (1995), (2002 carrie I. shivers et.al.)} have remarkably different results. One study assessed the pinch grip strength using a custom made pinch dynamometer, a Wheatstone bridge configuration with bars spacing at 1, 3, 5, 7 cm mounted such that it was necessary to squeeze the bars equally to achieve a valid force measurement, in 16 participants. Results showed that pinch width had a significant effect on pinch force, with average force increasing from 1-5 cm, peaking at 5 cm and declining at 7 cm grip span (Fathallah, Kroemer, and Waldron, 1991).

Another study evaluated pinch grip strength in 17 participants with a pinch grip dynamometer developed by their own research team, where a steel handle was attached to Chatillon digital pull/ push gauge. The handle could be adjusted to seven fixed widths : 2.0, 3.2, 4.4, 5.6, 6.8, 8.0 and 9 cm. the results showed that pinch width had a significant effect on force production, inferencing the strongest grip span was smallest span (2.0 cm) and the weakest grip span was the largest span (9.2 cm), with a decline between these points (Imrhan and Rahman,1995).

Another study showed the relationship between lateral pinch grip span on lateral pinch grip strength, where they prepared a custom made gauge with grip span ranging from 4 mm to participant's maximal lateral grip span. The results showed that at the maximal lateral span the grip strength was 40 % more than at the smallest grip span (2002 carrie I. shivers et.al.).

Another study shows that, in adult men, optimal hand grip span can be set at a fixed value (5.5 cm). As the previous studies showed that optimal pinch grip span exists Between 5-7 cm. So taking all above studies into consideration we came to a consensus to keep the pinch grip span as 5.5 cms.

Hand performance is highly affected by forearm position by degree of supination or pronation. (Agresti and Finlay, 1986, Marley and Wehrman, 1992, Richards et al. 1996).

Pinch grip span is a factor that may be under the control of the ergonomist, and so understanding the relationship between pinch grip span and pinch grip force could lead to interventions which will reduce the risk of fatigue, discomfort, and injury.

The standard device to measure pinch grip till date is pinch gauge mechanical/ hydraulic, which gives a reading in pounds/ kilograms with a small pinch grip span. So taking all above studies in consideration we designed a feasible, new custom made pinch grip biofeedback device with a larger pinch grip span which gives real time measurements.

Object of the Invention

The object of this invention is to device a feasible custom made device which can be used an evaluation as well as a treatment device for pinch grip strength.

The second object of this invention is to device a biofeedback device which gives real time measurements and value for pinch grip strength for each and every second.

The third object of this invention is to design a device taking into consideration the hand anthropometric (pinch grip span) and biomechanical properties.

Brief Description of Figures

Figure 1 shows schematic representation of device.

Figure 2 shows the 3 D View of the device.

Figure 3 shows the Sensory Assembly which includes the sensors pasted on the either side of the sensory assembly.

Figure 4 shows the Hand Held Assembly with microcontroller.

Detailed Description of Figures
Embodiments consistent with present disclosure are expounded below by reference to accompanying drawings. The embodiments given herein are only part of the embodiments of the present disclosure. Those skilled in the art can derive other embodiments from the embodiments given herein without making any creative effort, and all such embodiments are covered by the protection scope of the present disclosure.

The pinch grip device has two main assemblies, one being Hand Held Assembly (1) and other being sensor Assembly (2). The Sensor Assembly (2) is positioned on the top of Hand Held Assembly (1).
Figure 1 shows the perspective view of the complete embodiment which depicts both the assemblies. The Sensor Assembly (2) houses the Flex Force Sensor (3), (4). The Flex Force sensor (3) is fixed on the right side and Flexi force sensor (4) on the left side of the sensor Assembly (2).

Figure 2 shows the 3 - D view of the embodiment, which depicts the positioning of the Flex Sensor (3) and Flex sensor (4).

Figure 3 shows the functioning of the sensor assembly (2). The Flex force sensor (3), (4) provides a resistive change proportional to the applied pressure on the sensors. The Flex force sensor (3), (4) range in 0 - 25 lbs.

In the preferred embodiment, Figure 4 illustrates the diagrammatic block diagram of the Pinch Grip Device. The Flex sensors (3), (4) is interfaced with microcontroller, such that it captures the force sensor (3), (4) information. The embedded software enables to provide suitable output from microcontroller (5) such that the output can be visualized using laptop/ computer (6) with USB facility. The evaluation of the device is executed by seating the participant comfortably in chair with arm rest with shoulder adducted 0 degree rotation, elbow 90 degree flexion, forearm in neutral position wrist neutrally placed. The device will be held in examiners hand so that the weight of device would not be felt by the individual.

Tip to Tip - The individual should be asked to place the tip of the index finger and thumb on the sensing areas on the either side and press as hard as he/she can. The forearm was placed in neutral position, as it has been concluded by many studies supination or neutral position increases or does not affects grip strength whereas pronation decreases.

Pad to Pad - The individual should be asked to place the pulp of index finger and thumb on either sides over the sensing area and press as hard as he/she can. Side to Pad - The individual should be asked to place the pulp of the thumb on the top and the side of the index finger down over the sensing area and press as hard as he/she can. Dated This

We claim -

1. Pinch Grip Biofeedback Device consists of Hand Held Assembly with Microcontroller having dimensions (11*7*4) cm.

2. A pinch grip biofeedback device consists of Sensor Assembly having dimensions (2.5*5.5*1.7) cm.

3. Hand Held Assembly has the provision to hold Sensor Assembly on the top of the device

4. As claimed in claim 2 Pinch Grip Device will house the Flex Sensors on both right and left hand sides of Sensor Assembly.

5. The device is designed taking into consideration hand anthropometric and biomechanical properties designed the device with wider Pinch Grip Span (5.5 cms).

6. As hand performance is highly affected by forearm position by degree of supination or pronation or kept in neutral position so, testing procedure is slightly different from Standard American society of Hand Therapists (ASHT) ie, while measuring the pinch grip strength the forearm component to be kept in neutral position.

7. Pinch Grip Biofeedback Device gives real time measurements for the value of pinch grip strength in pounds (0 - 25 lbs) for each and every second for thumb and index finger individually.

8. Pinch Grip Biofeedback Device can be used as an evaluation device for pinch grip strength measurement and treatment device based on feasibility.