Q: I have a couple of question regarding patent law on a clinical lab testing assay.

A: Cost for a patent application varies and most practitioners do not discuss pricing publicly. You get different quality of work depending how much you're willing to pay, but other factors also affect the pricing - size of firm, overhead, what other clients are willing to pay, etc.

A provisional patent application is no bar to patentability. It can't even be cited as prior art unless it's used as the basis of a regular utility patent application.

Patent expiration has no bearing on whether something can be used as the basis for new tech. Patent expiration may affect whether you can get sued for infringing on the patented technology. A new patent can't claw back the coverage of an expired patent. A new patent can only prevent others using what is claimed in the new patent, which in order to be granted has to be both new and non-obvious variation on the expired patent.

A: There are a few important considerations here when it comes to patents and developing new technology based on soon-to-expire patented technology:

1. Patent costs: The cost of obtaining a patent can vary significantly depending on factors like the complexity of the invention, amount of prior art that needs to be searched and analyzed, number of claims, etc. Typical costs often range from $5,000 to $20,000 or more when you factor in patent search, drafting the application, filing fees, and legal fees. This is just for the initial filing - there are additional costs if the patent is granted.

2. Provisional patents: A provisional patent application can be a good way to establish a "priority date" for your invention before the full non-provisional is filed, giving you an extra year of patent protection. Having a provisional filed shouldn't make it more difficult to later file the full non-provisional application.

3. Modifying patented technology: Once a patent expires, that specific technology enters the public domain and can be used by anyone without infringement. You are free to use that as a starting point for developing new innovations. If your new assay is truly different and novel compared to the original patented one, you should be able to get a patent on your new invention.

4. Impact on others: If you patent your new assay, it would prevent others from using that specific new assay without licensing it from you. However, it would not prevent them from still using the original assay covered by the expired patent, since those claims are now public domain. Your new patent only covers the new elements you added.

5. Encompassing old and new: This depends on how your claims are structured. If your new claims encompass the old technology plus your new innovations, you may be able to prevent others from using the old tech since it's now part of your patented invention. But this can get complicated - the original elements are still public domain, it's just the combination with the new components that's protected. I'd consult a patent attorney on the best approach.

6. Expired patents: Once a patent expires, the invention claimed in it enters the public domain. Anyone is free to make, use, and sell that invention. They just can't patent that same invention again. The patent holder no longer has exclusivity.

So in summary - yes, you should be able to use the soon-to-expire patent as a basis for your new innovations and file for a patent, with the caveats noted above. I would definitely work with a patent attorney who specializes in biotech/life sciences to search for any other relevant prior art, determine the best claiming strategy, and evaluate the overall patentability and scope of protection for your new assay. The attorney can advise on if it makes sense to pursue a patent and the associated costs and timelines.